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EP0821141A1 - Internal combustion engine valve drive with rocker arm supported by eccentric shaft - Google Patents

Internal combustion engine valve drive with rocker arm supported by eccentric shaft Download PDF

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Publication number
EP0821141A1
EP0821141A1 EP97110694A EP97110694A EP0821141A1 EP 0821141 A1 EP0821141 A1 EP 0821141A1 EP 97110694 A EP97110694 A EP 97110694A EP 97110694 A EP97110694 A EP 97110694A EP 0821141 A1 EP0821141 A1 EP 0821141A1
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EP
European Patent Office
Prior art keywords
eccentric shaft
valve
valve lift
combustion engine
internal combustion
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP97110694A
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German (de)
French (fr)
Other versions
EP0821141B1 (en
Inventor
Harald Unger
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Bayerische Motoren Werke AG
Original Assignee
Bayerische Motoren Werke AG
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Publication date
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Publication of EP0821141A1 publication Critical patent/EP0821141A1/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
    • 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
    • F01L13/0063—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 modification of cam contact point by displacing an intermediate lever or wedge-shaped intermediate element, e.g. Tourtelot
    • 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
    • F01L13/0021—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 modification of rocker arm ratio
    • F01L13/0026—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 modification of rocker arm ratio by means of an eccentric
    • 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
    • F01L2001/0475—Hollow 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
    • F01L2820/00—Details on specific features characterising valve gear arrangements
    • F01L2820/03—Auxiliary actuators
    • F01L2820/032—Electric motors

Definitions

  • the invention relates to a valve train of an internal combustion engine an eccentric shaft supporting, actuated by cams and in particular designed as a rocker arm transmission members, the valve lift can be changed by turning the eccentric shaft.
  • Such one Valve train is, inter alia, from DE 42 23 172 C1 or DE 42 23 173 A1 known.
  • each an eccentric for a rocker arm which has at least one internal combustion engine lift valve actuated, is provided and wherein at least two internal combustion engine cylinders are arranged in series, the valve lift curve, d. H. in particular the maximum achievable valve lift of all of these, for example Lift valves designed as intake valves are simultaneously changed will.
  • these globe valves are as usual and known to the person skilled in the art must be opened against the force of a so-called valve closing spring, must also when the eccentric shaft is rotated in the sense of increasing the valve stroke always a certain proportion of this valve closing spring force be overcome.
  • a single eccentric shaft for the cylinders arranged in series the cam is always outside at least for one of these cylinders its base circle phase, in which the globe valve is closed.
  • the eccentric shaft for example can be provided as an electric motor trained servomotor, the is controlled accordingly by suitable control electronics.
  • the eccentric shaft can be rotated by this servomotor a position in which a small valve lift is generated towards one Position, which gives the maximum possible valve lift, is due to the Valve closing spring forces require a relatively high torque, which is a disproportionately strong and therefore large servomotor / electric motor required.
  • a force storage element which is designed in particular as a spring element, acts on the eccentric shaft and supports the servomotor when the eccentric shaft is rotated in the direction of a larger valve lift.
  • FIG. 1 that is required in a diagram to rotate the eccentric shaft Torque depending on the respective eccentric shaft positions shows.
  • FIG. 2a shows detail A
  • FIG. 2b shows detail B from FIG. 2.
  • valve train according to The preamble of claim 1 is in its entirety to the two at the beginning referred to documents DE 42 23 172 C1 and DE 42 23 173 A1
  • the present invention also other valve trains with at least one eccentric shaft on which different from Support cam-actuated transmission elements, is applicable.
  • the valve stroke or the valve lift curve of the lift valves actuated by the rocker arms can be changed.
  • the torque required to turn the eccentric shaft is shown qualitatively in Fig. 1.
  • the rotation angle of the eccentric shaft is on the abscissa of this diagram applied, with a twist angle of 0 ° the minimum possible Valve lift - this can be a zero lift, for example. H. the lift valve is not opened at all - corresponds, while at an angle of rotation of 180 ° gives the maximum possible valve lift. On the ordinate of this diagram is (qualitatively) the required torque applied to turn the eccentric shaft into a desired position.
  • the different waveforms 1 through 5 in this diagram are explained below:
  • Curve 1 indicates the torque that is required, the eccentric shaft (for example according to DE 42 23 172 C1) without any additional measures from the position 0 °, ie from the position of the minimum possible valve lift, to any other position 180 °, ie that of the maximum possible valve stroke.
  • a torque value M ' max is required to reach the eccentric shaft position of 180 °.
  • This required torque can in principle be applied by a servomotor, for example an electric motor.
  • valve stroke is then to be reduced again starting from this eccentric shaft position 180 ° or also from a position in the range between 0 ° and 180 °, a torque corresponding to curve 2, starting from the respective starting value, is required.
  • negative torque values have to be applied, or the servomotor or electric motor rotates in the opposite direction.
  • the amount of torque to be applied is less, since when the eccentric shaft is turned back, the valve closing spring forces at least partially compensate for the frictional resistance, while when the valve is turned from 0 ° to 180 °, the increasing valve closing spring forces are added to the frictional resistance.
  • the frictional resistances in the system are so high that the eccentric shaft, once positioned, maintains its respective position, ie the eccentric shaft is not twisted by the valve closing spring forces alone.
  • Curve 3 indicates which torque is to be applied in order to turn the eccentric shaft from 0 ° to 180 °, ie from the position of the minimum valve lift to the position of the maximum possible valve lift. It can be seen that a relation to the amount of M 'max is significantly lower amount M max required to the eccentric shaft to rotate, for example, from the position 90 ° to position 180 ° (these values are referredsver-understandable way of example only). The torque to be applied by the servomotor to turn the eccentric shaft is therefore significantly lower, so that a smaller servomotor / electric motor can be used.
  • this curve 3 intersects the abscissa at the position of approximately 52 angular degrees, which means that on this curve 3 coming from the left, no additional torque of an actuating motor is required at all to bring the eccentric shaft into this position 52 °.
  • the eccentric shaft is rotated into the 52 ° position solely by the spring element. Since this eccentric shaft position 52 ° corresponds to a valve lift that is greater than the minimum possible valve lift, the eccentric shaft is thus advantageously brought into this position solely by the spring element, which results in a larger than the minimum valve lift.
  • a torque M max is required which is significantly lower than the torque M ' max .
  • a constructive embodiment for the servomotor of the eccentric shaft supportive when turning the valve into a position of larger valve lift Spring element or energy storage element is together with the with the reference number 11 designated eccentric shaft in Figs. 2, 2a, 2b shown, with the cut line lying to the left of the breaking line 9 shown Eccentric shaft half rotated by 90 ° with respect to the right-hand side is.
  • Electric motor trained servomotor for positioning the eccentric shaft 11 it is not shown, for example, as Electric motor trained servomotor for positioning the eccentric shaft 11, however, this can be arranged in any manner familiar to the person skilled in the art be.
  • the reference number 10 designated spring element formed as a twisted torsion bar and arranged within the hollow eccentric shaft 11 along the axis thereof.
  • This torsion bar spring 10 is at the end by means of two half-shell elements 12 on the eccentric shaft 11 on the one hand and on a rigid component attached to the internal combustion engine on the other hand, the fixation of the Torsion bar spring 10 in the half-shell elements 12 as can be seen in each case is form-fitting.
  • the bent ends of the spring element 10 are thus form-fitting by those working together Half-shell elements 12 added.
  • the spring element is on the right-hand side with respect to the eccentric shaft 11 according to FIG. 2 10 is thus rotatably connected to the internal combustion engine, is on the left this twisted torsion bar spring 10, however, non-rotatably with the eccentric shaft 11 connected.
  • this spring element 10 of the eccentric shaft 11 such an at least supporting torque imprint that the eccentric shaft in one position as described is rotated, which is a larger one based on the current position Valve stroke results.
  • another spring element or in general Force storage element can be used as the torsion bar spring 10.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Valve Device For Special Equipments (AREA)

Abstract

The mechanism is supported on an eccentric shaft (11) which is driven by cams and is formed as pivot levers acting as transmission members. The valve lift is variable through twisting of the eccentric shaft which is provided with a positioning motor. A force accumulator component which is formed as a spring part (10) engages on the shaft, supporting the motor by a desired twisting of the shaft in the direction of a larger valve lift. The force accumulator component tries to move the eccentric shaft without the effect of the positioning motor into such a position, thus producing a larger valve lift than the minimal possible. The spring part may be formed as a twisted rotary rod sprung held inside the hollow eccentric shaft.

Description

Die Erfindung betrifft einen Ventiltrieb einer Brennkraftmaschine mit sich an einer Exzenterwelle abstützenden, von Nocken betätigten und insbesondere als Schwinghebel ausgebildeten Übertragungsgliedern, wobei der Ventilhubverlauf durch Verdrehen der Exzenterwelle veränderbar ist. Ein derartiger Ventiltrieb ist unter anderem aus der DE 42 23 172 C1 oder der DE 42 23 173 A1 bekannt.The invention relates to a valve train of an internal combustion engine an eccentric shaft supporting, actuated by cams and in particular designed as a rocker arm transmission members, the valve lift can be changed by turning the eccentric shaft. Such one Valve train is, inter alia, from DE 42 23 172 C1 or DE 42 23 173 A1 known.

Mittels dieser mehrere Exzenter aufweisenden Exzenterwelle, wobei jeweils ein Exzenter für einen Schwinghebel, welcher zumindest ein Brennkraftmaschinen-Hubventil betätigt, vorgesehen ist und wobei zumindest zwei Brennkraftmaschinen-Zylinder in Reihe angeordnet sind, kann der Ventilhubverlauf, d. h. insbesondere der maximal erreichbare Ventilhub aller dieser beispielsweise als Einlaßventile ausgebildeten Hubventile gleichzeitig verändert werden. Da diese Hubventile jedoch wie üblich und dem Fachmann bekannt gegen die Kraft einer sogenannten Ventilschließfeder geöffnet werden müssen, muß auch bei einem Verdrehen der Exzenterwelle im Sinne einer Ventilhubvergrößerung stets ein gewisser Anteil dieser Ventilschließfeder-Kraft überwunden werden. Bei einer mehrzylindrigen Brennkraftmaschine mit einer einzigen Exzenterwelle für die in Reihe angeordneten Zylinder wird sich nämlich stets zumindest für einen dieser Zylinder der Nocken außerhalb seiner Grundkreisphase, in welcher das Hubventil geschlossen ist, befinden. Zum gewünschten Verdrehen der Exzenterwelle kann dabei ein beispielsweise als Elektromotor ausgebildeter Stellmotor vorgesehen sein, der von einer geeigneten Steuerelektronik entsprechend angesteuert wird. Soll nun die Exzenterwelle von diesem Stellmotor verdreht werden und zwar aus einer Position heraus, in der ein geringer Ventilhub erzeugt wird hin zu einer Position, die den maximal möglichen Ventilhub ergibt, so ist aufgrund der Ventilschließfeder-Kräfte hierfür ein relativ hohes Drehmoment vonnöten, was einen unverhältnismäßig starken und somit großen Stellmotor/Elektromotor erfordert.By means of this eccentric shaft having several eccentrics, each an eccentric for a rocker arm, which has at least one internal combustion engine lift valve actuated, is provided and wherein at least two internal combustion engine cylinders are arranged in series, the valve lift curve, d. H. in particular the maximum achievable valve lift of all of these, for example Lift valves designed as intake valves are simultaneously changed will. However, since these globe valves are as usual and known to the person skilled in the art must be opened against the force of a so-called valve closing spring, must also when the eccentric shaft is rotated in the sense of increasing the valve stroke always a certain proportion of this valve closing spring force be overcome. With a multi-cylinder internal combustion engine a single eccentric shaft for the cylinders arranged in series the cam is always outside at least for one of these cylinders its base circle phase, in which the globe valve is closed. For the desired rotation of the eccentric shaft, for example can be provided as an electric motor trained servomotor, the is controlled accordingly by suitable control electronics. Should now the eccentric shaft can be rotated by this servomotor a position in which a small valve lift is generated towards one Position, which gives the maximum possible valve lift, is due to the Valve closing spring forces require a relatively high torque, which is a disproportionately strong and therefore large servomotor / electric motor required.

Maßnahmen aufzuzeigen, mit Hilfe derer das erforderliche Drehmoment zum Verdrehen der Exzenterwelle aus einer Position geringen Ventilhubs heraus hin zu einer Position größeren Ventilhubes verringert werden kann, ist Aufgabe der vorliegenden Erfindung.
Zur Lösung dieser Aufgabe ist vorgesehen, daß neben dem Stellmotor an der Exzenterwelle ein insbesondere als Federelement ausgebildetes Kraftspeicherelement angreift, welches bei einer gewünschten Verdrehung der Exzenterwelle in Richtung auf einen größeren Ventilhub den Stellmotor unterstützt. Vorteilhafte Aus- und Weiterbildungen sind Inhalt der Unter-ansprüche.It is the object of the present invention to show measures by means of which the torque required for rotating the eccentric shaft from a position with a small valve lift to a position with a larger valve lift can be reduced.
To solve this problem, it is provided that, in addition to the servomotor, a force storage element, which is designed in particular as a spring element, acts on the eccentric shaft and supports the servomotor when the eccentric shaft is rotated in the direction of a larger valve lift. Advantageous training and further education are included in the sub-claims.

Zur näheren Erläuterung der Erfindung wird zunächst auf Fig. 1 verwiesen, die in einem Diagramm das zum Verdrehen der Exzenterwelle erforderliche Drehmoment in Abhängigkeit von den jeweiligen Exzenterwellen-Positionen zeigt. For a more detailed explanation of the invention, reference is first made to FIG. 1, that is required in a diagram to rotate the eccentric shaft Torque depending on the respective eccentric shaft positions shows.

In Fig. 2 ist dann ein bevorzugtes Ausführungsbeispiel der Erfindung dargestellt, und zwar eine Exzenterwelle mit integriertem Federelement, wobei Fig. 2a den Ausschnitt A und Fig. 2b den Ausschnitt B aus Fig. 2 zeigt.A preferred exemplary embodiment of the invention is then shown in FIG. namely an eccentric shaft with an integrated spring element, with Fig. 2a shows detail A and FIG. 2b shows detail B from FIG. 2.

Bezüglich der konstruktiven Ausgestaltung eines Ventiltriebs nach dem Oberbegriff des Anspruchs 1 wird in vollem Umfang auf die beiden eingangs genannten Schriften DE 42 23 172 C1 sowie DE 42 23 173 A1 Bezug genommen, wobei sich die vorliegende Erfindung selbstverständlich auch auf andere Ventiltriebe mit zumindest einer Exzenterwelle, an der sich von Nocken betätigte Übertragungsglieder abstützen, anwendbar ist. Dabei ist - wie bereits kurz erläutert - durch Verdrehen der Exzenterwelle der Ventilhub bzw. Ventilhubverlauf der von den Schwinghebeln betätigten Hubventile veränderbar. Das zum Verdrehen der Exzenterwelle erforderliche Drehmoment ist qualitativ in Fig. 1 dargestellt.With regard to the structural design of a valve train according to The preamble of claim 1 is in its entirety to the two at the beginning referred to documents DE 42 23 172 C1 and DE 42 23 173 A1, the present invention, of course, also other valve trains with at least one eccentric shaft on which different from Support cam-actuated transmission elements, is applicable. Here is - as already briefly explained - by turning the eccentric shaft the valve stroke or the valve lift curve of the lift valves actuated by the rocker arms can be changed. The torque required to turn the eccentric shaft is shown qualitatively in Fig. 1.

Auf der Abszisse dieses Diagrammes ist der Verdrehwinkel der Exzenterwelle aufgetragen, wobei ein Verdrehwinkel von 0° dem minimal möglichen Ventilhub - hier kann es sich beispielsweise um einen Nullhub handeln, d. h. das Hubventil wird überhaupt nicht geöffnet - entspricht, während sich bei einem Verdrehwinkel von 180° der maximal mögliche Ventilhub ergibt. Auf der Ordinate dieses Diagrammes ist (qualitativ) das erforderliche Drehmoment zum Verdrehen der Exzenterwelle in eine gewünschte Position auf-getragen. Die verschiedenen Kurvenverläufe 1 bis 5 in diesem Diagramm werden im folgenden erläutert:The rotation angle of the eccentric shaft is on the abscissa of this diagram applied, with a twist angle of 0 ° the minimum possible Valve lift - this can be a zero lift, for example. H. the lift valve is not opened at all - corresponds, while at an angle of rotation of 180 ° gives the maximum possible valve lift. On the ordinate of this diagram is (qualitatively) the required torque applied to turn the eccentric shaft into a desired position. The different waveforms 1 through 5 in this diagram are explained below:

Die Kurve 1 gibt dasjenige Drehmoment an, welches erforderlich ist, die Exzenterwelle (beispielsweise nach der DE 42 23 172 C1) ohne irgendwelche Zusatzmaßnahmen von der Position 0°, d. h. von der Position des minimal möglichen Ventilhubes, in jede andere Position bis hin zur Position 180°, d. h. derjenigen des maximal möglichen Ventilhubes, zu verdrehen. Zu überwinden sind hierbei zunächst Reibungsverluste, so daß diese Kurve 1 zwangsläufig bei einem Drehmomentwert > "0" startet. Mit zunehmendem Verdrehwinkel und somit zunehmendem Ventilhub ist eine immer weiter ansteigende Ventilschließfeder-Kraft zu überwinden, weshalb zum Erreichen der Exzenterwellenposition von 180° ein Drehmomentwert M'max erforderlich ist. Dieses erforderliche Drehmoment kann grundsätzlich von einem Stellmotor, beispielsweise Elektromotor aufgebracht werden.Curve 1 indicates the torque that is required, the eccentric shaft (for example according to DE 42 23 172 C1) without any additional measures from the position 0 °, ie from the position of the minimum possible valve lift, to any other position 180 °, ie that of the maximum possible valve stroke. First there are friction losses to overcome, so that curve 1 inevitably starts at a torque value>"0". With increasing angle of rotation and thus increasing valve lift, an ever increasing valve closing spring force has to be overcome, which is why a torque value M ' max is required to reach the eccentric shaft position of 180 °. This required torque can in principle be applied by a servomotor, for example an electric motor.

Soll anschließend ausgehend von dieser Exzenterwellenposition 180° oder auch von einer Position im Bereich zwischen 0° und 180° der Ventilhub wieder reduziert werden, so ist hierfür ein Drehmoment entsprechend der Kurve 2, ausgehend vom jeweiligen Startwert erforderlich. Wegen des Zurückdrehens der Exzenterwelle sind hierbei negative Drehmomentwerte aufzubringen, bzw. der Stellmotor oder Elektromotor dreht in der entgegengesetzten Richtung. Der Betrag des aufzubringenden Drehmomentes ist hierbei geringer, da beim Zurückdrehen der Exzenterwelle die Ventilschließfeder-Kräfte die Reibungswiderstände zumindest teilweise kompensieren, während beim Verdrehen von 0° in Richtung auf 180° die zunehmenden Ventilschließfeder-Kräfte additiv zu den Reibungswiderständen hinzukommen.
Üblicherweise sind dabei die Reibungswiderstände im System so hoch, daß die einmal positionierte Exzenterwelle ihre jeweilige Position beibehält, d.h. die Exzenterwelle wird allein durch die Ventilschließfeder-Kräfte nicht verdreht.If the valve stroke is then to be reduced again starting from this eccentric shaft position 180 ° or also from a position in the range between 0 ° and 180 °, a torque corresponding to curve 2, starting from the respective starting value, is required. Because of the turning back of the eccentric shaft, negative torque values have to be applied, or the servomotor or electric motor rotates in the opposite direction. The amount of torque to be applied is less, since when the eccentric shaft is turned back, the valve closing spring forces at least partially compensate for the frictional resistance, while when the valve is turned from 0 ° to 180 °, the increasing valve closing spring forces are added to the frictional resistance.
Usually, the frictional resistances in the system are so high that the eccentric shaft, once positioned, maintains its respective position, ie the eccentric shaft is not twisted by the valve closing spring forces alone.

Da der Betrag des Drehmomentwertes M'max relativ hoch ist, wäre zum Positionieren der Exzenterwelle ohne irgendwelche Zusatzmaßnahmen ein relativ starker Elektromotor vonnöten. Um den Betrag des maximal benötigen Drehmomentes zu reduzieren, ist nun erfindungsgemäß ein Federelement bzw. Kraftspeicherelement vorgesehen, welches die Exzenterwelle seinerseits zu verdrehen trachtet, und zwar in Richtung auf einen größeren Ventilhub hin. Dieses Federelement unterstützt somit den Stellmotor bei einer Verdrehbewegung der Exzenterwelle in Richtung auf einen größeren Ventilhub, so daß das vom Stellmotor aufzubringende Drehmoment dementsprechend reduziert wird. Mit einem derartigen Federelement er-geben sich dann zum Verdrehen der Exzenterwelle die Kurvenverläufe 3 und 4,und zwar mit der weiter in das Diagramm eingezeichneten Kurve 5, welche das vom Federelement auf die Exzenterwelle aufgebrachte Dreh-moment für sich alleine darstellt. Eine Addition der Kurven 1 und 5 ergibt somit die Kurve 3, eine Addition der Kurven 2 und 5 die Kurve 4.Since the amount of the torque value M ' max is relatively high, a relatively strong electric motor would be required to position the eccentric shaft without any additional measures. In order to reduce the amount of maximum torque required, a spring element or energy storage element is now provided according to the invention, which in turn tries to turn the eccentric shaft, in the direction of a larger valve stroke. This spring element thus supports the servomotor when the eccentric shaft rotates in the direction of a larger valve stroke, so that the torque to be applied by the servomotor is reduced accordingly. With such a spring element, the curves 3 and 4 are then obtained for rotating the eccentric shaft, specifically with curve 5 further drawn in the diagram, which represents the torque applied by the spring element to the eccentric shaft on its own. An addition of curves 1 and 5 thus results in curve 3, an addition of curves 2 and 5 results in curve 4.

Die Kurve 3 gibt an, welches Drehmoment aufzubringen ist, um die Exzenterwelle von 0° auf 180° zu verdrehen, d. h. von der Position des minimalen Ventilhubes hin zur Position des maximal möglichen Ventilhubes. Man erkennt, daß ein gegenüber dem Betrag M'max deutlich geringerer Betrag Mmax erforderlich ist, um die Exzenterwelle beispielsweise von der Position 90° zur Position 180° zu verdrehen (diese genannten Werte sind selbstver-ständlich nur beispielhaft). Das vom Stellmotor zum Verdrehen der Exzenter-welle aufzubringende Drehmoment ist daher deutlich geringer, so daß einkleinerer Stellmotor/Elektromotor zum Einsatz kommen kann.
Wie ersichtlich schneidet diese Kurve 3 bei der Position van ca. 52 Winkelgraden die Abszisse, was bedeutet, daß auf dieser Kurve 3 von links her kommend überhaupt kein zusätzliches Drehmoment eines Stellmotores erforderlich ist, um die Exzenterwelle in diese Position 52° zu bringen. Beispielsweise ausgehend von der Position 0° wird somit die Exzenterwelle alleine durch das Federelement in die Position 52° verdreht. Da diese Exzenterwellenposition 52° einem Ventilhub entspricht, der größer ist als der minimal mögliche Ventilhub, wird somit vorteilhafterweise die Exzenterwelle allein durch das Federelement in diese Position gebracht, die einen größeren als den minimalen Ventilhub ergibt. Vorteilhafterweise stellt sich somit auch bei einem Ausfall des Stellmotores zum Verdrehen der Exzenterwelle stets ein gewisser Ventilhub ein, der ausreichend ist, die Brennkraftmaschine in noch befriedigendem Maße zu betreiben. Um dann ausgehend von dieser Position des sogenannten Null-Drehmomentes den maximal möglichen Ventilhub und somit die Exzenterwellenposition 180° zu erreichen, wird ein Drehmoment Mmax benötigt, welches deutlich geringer ist als das Drehmoment M'max.Curve 3 indicates which torque is to be applied in order to turn the eccentric shaft from 0 ° to 180 °, ie from the position of the minimum valve lift to the position of the maximum possible valve lift. It can be seen that a relation to the amount of M 'max is significantly lower amount M max required to the eccentric shaft to rotate, for example, from the position 90 ° to position 180 ° (these values are referred selbstver-understandable way of example only). The torque to be applied by the servomotor to turn the eccentric shaft is therefore significantly lower, so that a smaller servomotor / electric motor can be used.
As can be seen, this curve 3 intersects the abscissa at the position of approximately 52 angular degrees, which means that on this curve 3 coming from the left, no additional torque of an actuating motor is required at all to bring the eccentric shaft into this position 52 °. For example, starting from the 0 ° position, the eccentric shaft is rotated into the 52 ° position solely by the spring element. Since this eccentric shaft position 52 ° corresponds to a valve lift that is greater than the minimum possible valve lift, the eccentric shaft is thus advantageously brought into this position solely by the spring element, which results in a larger than the minimum valve lift. Advantageously, even if the servomotor fails to turn the eccentric shaft, there is always a certain valve lift that is sufficient to operate the internal combustion engine to a satisfactory extent. In order to then, starting from this position of the so-called zero torque, achieve the maximum possible valve lift and thus the eccentric shaft position 180 °, a torque M max is required which is significantly lower than the torque M ' max .

Um danach ausgehend von dieser Position des maximal möglichen Ventilhubes wieder auf die Position des minimalen Ventilhubes zu gelangen, wird ein Drehmomentverlauf entsprechend der Kurve 4 benötigt. Der Betrag dieses dann negativen Drehmomentes wegen des Zurückdrehens der Exzenterwelle ist jedoch ebenfalls nicht größer als der Betrag Mmax, da - wie bereits erläutert - beim Zurückdrehen der Exzenterwelle hin zu geringerem Ventilhub die Reibungsverluste teilweise durch die abnehmenden Ventilschließfeder-Kräfte kompensiert werden. Im übrigen muß aufgrund der Krafteinwirkung durch das Federelement ein negatives Drehmoment auf-gebracht werden, um ausgehend von der Position des minimalen Ventil-hubes bei einem Exzenterwellenwinkel von 0° die sog. Null-Drehmoment-position bei ca. 52° zu erreichen, d.h um auf der Kurve 3 von der Stellung 0° zur Stellung 52° nach rechts zu gelangen.In order to then return to the position of the minimum valve stroke from this position of the maximum possible valve stroke, a torque curve corresponding to curve 4 is required. However, the amount of this then negative torque due to the turning back of the eccentric shaft is also not greater than the amount M max, since - as already explained - when turning the eccentric shaft back towards a lower valve lift, the friction losses are partially compensated for by the decreasing valve closing spring forces. In addition, due to the action of force by the spring element, a negative torque must be applied in order to achieve the so-called zero torque position at approx. 52 °, starting from the position of the minimum valve lift at an eccentric shaft angle of 0 ° to move to the right on curve 3 from position 0 ° to position 52 °.

Eine konstruktive Ausführungsform für das den Stellmotor der Exzenterwelle beim Verdrehen derselben hin in eine Position größeren Ventilhubes unterstützende Federelement bzw Kraftspeicherelement ist zusammmen mit der mit der Bezugsziffer 11 bezeichneten Exzenterwelle in den Fig. 2, 2a, 2b dargestellt, wobei die linksseitig der Bruchlinie 9 liegende geschnitten dargestellte Exzenterwellen-Hälfte gegenüber der rechtsseitigen um 90° verdreht ist. Der Einfachheit halber nicht dargestellt ist der beispielsweise als Elektromotor ausgebildete Stellmotor zum Positionieren der Exzenterwelle 11, jedoch kann dieser in jeder dem Fachmann geläufigen Weise angeordnet sein.A constructive embodiment for the servomotor of the eccentric shaft supportive when turning the valve into a position of larger valve lift Spring element or energy storage element is together with the with the reference number 11 designated eccentric shaft in Figs. 2, 2a, 2b shown, with the cut line lying to the left of the breaking line 9 shown Eccentric shaft half rotated by 90 ° with respect to the right-hand side is. For the sake of simplicity, it is not shown, for example, as Electric motor trained servomotor for positioning the eccentric shaft 11, however, this can be arranged in any manner familiar to the person skilled in the art be.

Beim bevorzugten Ausführungsbeispiel nach Fig.2 ist das mit der Bezugsziffer 10 bezeichnete Federelement als tordierte Drehstabfeder ausgebildet und innerhalb der hohlen Exzenterwelle 11 längs deren Achse angeordnet. Diese Drehstabfeder 10 ist jeweils endseitig mittels zweier Halbschalenelemente 12 an der Exzenterwelle 11 einerseits und an einem starren Bauelement der Brennkraftmaschine andererseits befestigt, wobei die Fixierung der Drehstabfeder 10 in den Halbschalenelementen 12 wie er-sichtlich jeweils formschlüssig ausgebildet ist. Die gebogenen Enden des Federelementes 10 sind somit formschlüssig von den miteiander zusammenwirkenden Halbschalenelementen 12 aufgenommen.In the preferred embodiment according to FIG. 2, this is with the reference number 10 designated spring element formed as a twisted torsion bar and arranged within the hollow eccentric shaft 11 along the axis thereof. This torsion bar spring 10 is at the end by means of two half-shell elements 12 on the eccentric shaft 11 on the one hand and on a rigid component attached to the internal combustion engine on the other hand, the fixation of the Torsion bar spring 10 in the half-shell elements 12 as can be seen in each case is form-fitting. The bent ends of the spring element 10 are thus form-fitting by those working together Half-shell elements 12 added.

Die gemäß Fig.2 linksseitige Befestigung des Federelementes 10 an der Exzenterwelle 11 ist als Einzelheit A in Fig. 2a nochmals detailliert dargestellt. Man erkennt die beiden Halbschalenelemente 12, welche die Drehstabfeder 10 zwischen sich aufnehmen, und mittels einer Schraube 13 miteinander verbunden sind. Dabei sind die beiden Halbschalenelemente 12 wiederum durch Madenschrauben 14 in der Exzenterwelle 11 fixiert.
Rechtsseitig gemäß Einzelheit B ragt das Federelement 10 über die Exzenterwelle 11 hinaus. Auch hier sind zwei durch eine Schraube 13 miteinander verbundene Halbschalenelemente 12 vorgesehen, die die Drehstabfeder 10 formschlüssig zwischen sich aufnehmen. Diese Halbschalenelemente 12 sind dann mittels eines geeigneten Halteelementes 15 in sogenannten Lagerabschnitten 16 für die Exzenterwelle 11, welche Bestandteil der Brennkraftmaschine sind, fixiert.The attachment of the spring element 10 on the left-hand side according to FIG. 2 to the eccentric shaft 11 is shown again in detail as detail A in FIG. 2a. One can see the two half-shell elements 12, which hold the torsion bar spring 10 between them and are connected to one another by means of a screw 13. The two half-shell elements 12 are in turn fixed by grub screws 14 in the eccentric shaft 11.
On the right-hand side according to detail B, the spring element 10 projects beyond the eccentric shaft 11. Here, too, two half-shell elements 12 connected by a screw 13 are provided, which receive the torsion bar spring 10 between them in a form-fitting manner. These half-shell elements 12 are then fixed by means of a suitable holding element 15 in so-called bearing sections 16 for the eccentric shaft 11, which are part of the internal combustion engine.

Rechtsseitig bezüglich der Exzenterwelle 11 nach Fig. 2 ist das Federelement 10 somit drehfest mit der Brennkraftmaschine verbunden, linksseitig ist diese tordierte Drehstabfeder 10 jedoch drehfest mit der Exzenterwelle 11 verbunden. Auf diese Weise ist es möglich, mittels dieses Federelementes 10 der Exzentenwelle 11 ein derartiges zumindest unterstützendes Drehmoment aufzuprägen, daß die Exzenterwelle wie beschrieben in eine Position verdreht wird, welche ausgehend von der aktuellen Postion einen größeren Ventilhub ergibt. Dabei können selbstverständlich eine Vielzahl von Details insbesondere konstruktiver Art durchaus abweichend vom beschriebenen Ausführungsbeispiel gestaltet sein, ohne den Inhalt der Patentansprüche zu verlassen. Insbesondere kann auch ein anderes Federelement bzw. allgemein Kraftspeicherelement als die Drehstabfeder 10 zum Einsatz kommen.The spring element is on the right-hand side with respect to the eccentric shaft 11 according to FIG. 2 10 is thus rotatably connected to the internal combustion engine, is on the left this twisted torsion bar spring 10, however, non-rotatably with the eccentric shaft 11 connected. In this way it is possible by means of this spring element 10 of the eccentric shaft 11 such an at least supporting torque imprint that the eccentric shaft in one position as described is rotated, which is a larger one based on the current position Valve stroke results. Of course, you can do a variety of details in particular of a constructive nature quite different from the one described Embodiment can be designed without the content of the claims leave. In particular, another spring element or in general Force storage element can be used as the torsion bar spring 10.

Claims (4)

Ventiltrieb einer Brennkraftmaschine mit sich an einer Exzenterwelle (11) abstützenden, von Nocken betätigten und insbesondere als Schwinghebel ausgebildeten Übertragungsgliedern, wobei der Ventilhub durch Verdrehen der Exzenterwelle (11) veränderbar ist,
gekennzeichnet durch einen die Exzenterwelle (11) positionierenden Stellmotor sowie durch ein an der Exzenterwelle (11) angreifendes, insbesondere als Federelement (10) ausgebildetes Kraftspeicherelement, welches bei einer gewünschten Verdrehung der Exzenterwelle (11) in Richtung auf einen größeren Ventilhub den Stellmotor unterstützt.Valve train of an internal combustion engine with transmission members supported on an eccentric shaft (11), actuated by cams and in particular in the form of rocker arms, the valve stroke being changeable by rotating the eccentric shaft (11),
characterized by a positioning motor positioning the eccentric shaft (11) and by a force storage element engaging on the eccentric shaft (11), in particular in the form of a spring element (10), which supports the positioning motor when the eccentric shaft (11) is rotated in the direction of a larger valve stroke. Ventiltrieb nach Anspruch 1
dadurch gekennzeichnet, daß das insbesondere als Federelement (10) ausgebildete Kraftspeicherelement die Exzenterwelle (11) ohne Einwirkung des Stellmotors in eine solche Position zu bewegen versucht, welche einen größeren als den minimal möglichen Ventilhub ergibt.Valve train according to claim 1
characterized in that the force storage element, which is designed in particular as a spring element (10), tries to move the eccentric shaft (11) into a position without the action of the servomotor, which results in a valve stroke that is greater than the minimum possible. Ventiltrieb nach Anspruch 1 oder 2
dadurch gekennzeichnet, daß das Federelement (10) als innerhalb der hohlen Exzenterwelle (11) angeordnete tordierte Drehstabfeder ausgebildet ist.Valve train according to claim 1 or 2
characterized in that the spring element (10) is designed as a twisted torsion bar spring arranged within the hollow eccentric shaft (11). Ventiltrieb nach Anspruch 3,
dadurch gekennzeichnet, daß die Drehstabfeder (10) an ihren beiden Enden formschlüssig jeweils mittels zweier Halbschalenelemente (12) fixiert ist , und zwar einerseits an einem Endabschnitt der Exzenterwelle (11) und am gegenüberliegenden Exzenterwellenende außerhalb derselben in einem Exzenterwellen-Lagerabschnitt (16).Valve train according to claim 3,
characterized in that the torsion bar spring (10) is positively fixed at both ends by means of two half-shell elements (12), on the one hand at one end section of the eccentric shaft (11) and at the opposite eccentric shaft end outside the same in an eccentric shaft bearing section (16).
EP97110694A 1996-07-24 1997-07-01 Internal combustion engine valve drive with rocker arm supported by eccentric shaft Expired - Lifetime EP0821141B1 (en)

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DE19629881A DE19629881A1 (en) 1996-07-24 1996-07-24 Valve train of an internal combustion engine with rocker arms supported on an eccentric shaft
DE19629881 1996-07-24

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EP1211388A2 (en) * 2000-11-29 2002-06-05 Bayerische Motoren Werke Aktiengesellschaft Control method for a variable valve drive
DE10104038A1 (en) * 2001-01-31 2002-08-01 Bayerische Motoren Werke Ag Turning device for eccentric shaft of valve drive in IC engines has hydraulic vane cell pump supplied with medium by hydraulic vehicle system
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CN113958685A (en) * 2021-11-08 2022-01-21 重庆市巨亮机械制造有限责任公司 Powder metallurgy camshaft end combination

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CN110159385B (en) * 2019-06-26 2023-07-18 吉林大学 Simultaneous variable device of engine valve timing and lift and control method thereof

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Publication number Priority date Publication date Assignee Title
EP1211388A2 (en) * 2000-11-29 2002-06-05 Bayerische Motoren Werke Aktiengesellschaft Control method for a variable valve drive
EP1211388A3 (en) * 2000-11-29 2003-03-12 Bayerische Motoren Werke Aktiengesellschaft Control method for a variable valve drive
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DE10104038A1 (en) * 2001-01-31 2002-08-01 Bayerische Motoren Werke Ag Turning device for eccentric shaft of valve drive in IC engines has hydraulic vane cell pump supplied with medium by hydraulic vehicle system
DE102012204396A1 (en) * 2012-03-20 2013-09-26 Man Diesel & Turbo Se Valve drive for gas exchange valves of an internal combustion engine
CN113958685A (en) * 2021-11-08 2022-01-21 重庆市巨亮机械制造有限责任公司 Powder metallurgy camshaft end combination
CN113958685B (en) * 2021-11-08 2024-03-12 重庆市巨亮机械制造有限责任公司 Powder metallurgy camshaft end combination

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