EP3387234B1 - Internal combustion engine - Google Patents

Description

The invention relates to an internal combustion engine with a cylinder, a piston movably guided within the cylinder, a crankshaft and a connecting rod connecting the piston with a crank pin of the crank shaft, an eccentric sleeve rotatably accommodating the crank pin being rotatably mounted within a connecting rod eye of the connecting rod, which is rotatably mounted in at least two rotational orientations with respect to the connecting rod can be locked by means of a locking device.

Such an internal combustion engine enables operation with a variable compression ratio, which arises as a result of a variable distance between the crank pin and the piston which results as a function of the rotational orientation of the eccentric sleeve. By adapting the compression ratio to different operating states of the internal combustion engine, its thermodynamic function can be improved, and thus in particular the efficiency of the energy utilization and / or the power output in different load ranges can be improved.

A generic internal combustion engine is for example from the DE 197 03 948 C1 known. It also discloses that a rotation of the eccentric sleeve between the two rotational directions provided is normally carried out completely automatically by the forces acting on the eccentric sleeve as a result of the rotation of the crankshaft or the associated connecting rod movement. In addition, it could be provided to integrate a hydraulic motor into the connecting rod, by means of which the eccentric sleeve can be rotated in a state that is not locked by the locking device.

In practice, it has been shown that turning the eccentric sleeve in an internal combustion engine of the generic type, which is to be based solely on the forces acting on the eccentric sleeve from the operation of the internal combustion engine, does not function reliably or at least not quickly enough. Which continues in the DE 197 03 948 C1 The proposed integration of a hydraulic motor for active rotation of the eccentric sleeve is on the one hand very structurally complex and on the other hand increases the mass of the connecting rod considerably, which is particularly problematic due to the translatory back and forth movement of the connecting rod with the large accelerations that occur.

A generic internal combustion engine, in which a non-positive coupling device is provided, by means of which an eccentric sleeve can be temporarily coupled to a crankshaft in order to twist the eccentric sleeve relative to a connecting rod, is from the DE 10 2004 053 225 A1 known.

The DE 103 09 651 A1 on the other hand discloses an internal combustion engine in which a corresponding coupling device acts in a form-fitting manner.

An internal combustion engine in which a piston stroke can be adjusted by means of an eccentric sleeve is also from the EP 0 438 121 B1 known. However, it does not address how the eccentric sleeve there is to be twisted between the two intended rotational orientations.

For a corresponding internal combustion engine, as in the DE 102 30 429 A1 on the other hand, it is explicitly stated that such rotation of an eccentric sleeve with a connecting rod should take place when the locking device is open as a result of bearing reaction forces acting on it.

On the basis of this prior art, the object of the invention was to provide a way of ensuring that the eccentric sleeve can be safely and / or quickly rotated between the at least two rotational orientations in a generic internal combustion engine.

This object is achieved by means of an internal combustion engine according to claim 1. Advantageous refinements of the internal combustion engine according to the invention are the subject of the further claims and result from the following description of the invention.

To achieve the object, an internal combustion engine comprises at least one cylinder, a piston movably guided within the cylinder, a crankshaft and a connecting rod connecting the piston to a crankpin of the crankshaft, an eccentric sleeve, in turn, receiving the crankpin within a connecting rod eye of the connecting rod is rotatably mounted, which can be locked in at least two rotational orientations with respect to the connecting rod by means of a locking device, a coupling device is provided by means of which the eccentric sleeve is temporarily attached to the crankshaft and in particular to one or both Cheeks of the crank pin can be coupled to twist the eccentric sleeve relative to the connecting rod.

Accordingly, a rotation of the crankshaft or the crank pin relative to the connecting rod is used in the operation of the internal combustion engine in order to temporarily take the eccentric sleeve with it and thereby to quickly and safely rotate it from one rotational orientation to the other. This preferably takes place whenever the eccentric sleeve is not locked in one of the rotational orientations by means of the locking device. Since a crankshaft of an internal combustion engine normally always rotates in one direction of rotation, the eccentric sleeve is therefore always rotated in one (the same) direction of rotation relative to the connecting rod.

The coupling device acts (preferably exclusively) non-positively. This can in particular simplify the design of the coupling device and abruptly take the eccentric sleeve through the crankshaft, as could be the case with a form-fitting coupling device, can be avoided. This aspect can be particularly relevant because, when operating a generic internal combustion engine, there may be large differential angular velocities between the eccentric sleeve, which is arranged in one of the rotational orientations in a rotationally fixed manner with respect to the connecting rod, and the crankshaft or cheeks of the associated crankpin of the crankshaft.

The non-positive coupling device is designed in such a way that the crankshaft and the eccentric sleeve each have a coupling surface, which form a coupling gap with a gap width that decreases in a radial direction (ie radially inwards or radially outwards with respect to the axis of rotation of the eccentric sleeve within the connecting rod eye), wherein a coupling element can be brought into a first position and a second position, which differ with regard to the radial position within the coupling gap and thus with regard to the contact pressure between the coupling element and the coupling surfaces of the eccentric sleeve and the crankshaft. Such a coupling device is accordingly actuated radially, but acts primarily in the axial direction, i.e. the normally directed pressure forces which bring about a frictional connection in the contacting coupling surfaces are oriented at least more in the axial direction with respect to the axis of rotation of the eccentric sleeve within the connecting rod eye than radially to it.

It can preferably be provided that the first position of the coupling element by a relatively large contact pressure and the second position by a relatively small Contact pressure is marked. Furthermore, it can preferably be provided that the contact pressure in one (in particular the first) of the positions of the coupling element is so great that an essentially slip-free entrainment of the eccentric sleeve by the crankshaft occurs. It can also be preferably provided that the contact pressure in the other (in particular the second) of the positions of the coupling element is as low as possible and in particular essentially zero, so that friction losses due to a contacting relative movement between the coupling surfaces on the one hand and the coupling element on the other hand are advantageous can be avoided as possible if the locking device is locked in one of the rotational orientations with respect to the connecting rod by means of the locking device and consequently the internal combustion engine is operated with a compression ratio that is temporarily unchanged.

In a further preferred embodiment, it can be provided that the non-positive coupling device is designed to be self-reinforcing, so that frictional forces, which act between the coupling surfaces of the crankshaft and the eccentric sleeve on the one hand and the coupling element on the other hand as a result of an initial load, result in a further retraction of the coupling element, in particular for geometric reasons in the narrowing coupling gap, which is accompanied by a corresponding increase in the contact pressure. With such a coupling device, relatively high and in particular self-reinforcing friction forces can be generated with a relatively low initial load up to a slip-free coupling. The initial load for the coupling element of such a coupling device can result in particular from an elastic loading of the coupling element. Alternatively or in addition, this can also result from inertial forces (in particular gravitational and / or centrifugal forces). Provision can also be made to apply this output load actively by means of an actuator.

Provision can preferably be made for the coupling surface (s) of the crankshaft and / or the eccentric sleeve (and preferably also one or more coupling surfaces of the coupling element) to be oriented at an angle with respect to that plane which is aligned radially to the axis of rotation of the eccentric sleeve within the connecting rod eye are ≤ 5 ° and preferably about 3 °. In certain configurations of the coupling device, smaller angles can bring about such a large self-locking effect for the coupling element which is pulled further into the coupling gap as a result of the frictional forces that this makes it considerably more difficult to reliably release the coupling device. If the angle is too large, on the other hand, relatively large radially directed forces may be required to achieve the to achieve the required contact pressure between the coupling surfaces of the eccentric sleeve and the crankshaft and the coupling element.

In a preferred embodiment of the internal combustion engine according to the invention it can also be provided that the coupling element can be acted upon elastically. This is to be understood to mean that the coupling element can be acted upon by means of a prestressable spring element, which can also be the coupling element itself, in the direction of movement of the coupling element in one of the positions. Such elastic loading can ensure that the coupling element moves automatically into an initial position, as long as this is not influenced in any other way by a measure.

In a further preferred embodiment of such an internal combustion engine according to the invention, it can then be provided that the coupling element assumes the first position in the non-elastically loaded state or as a result of a constructive elastic loading, while the second position can be set by means of an activatable adjusting device. The first position can in particular be the one in which the contact pressure between the coupling surfaces of the eccentric sleeve and the crankshaft on the one hand and the coupling element on the other hand is higher than that in the second position. A "constructive elastic loading" is understood to mean a pretensioning of the spring element acting on the coupling element (or of the self-elastically deflected coupling element), which can be achieved without actively influencing the spring element as a result of constructive integration into the coupling device by supporting two sections, in particular end sections Sets spring element on elements of the coupling device.

It can preferably be provided that the adjusting device has an adjustable stop element for the coupling element. This can furthermore preferably be designed such that the stop element can be activated and deactivated, wherein it forms a stop for the coupling element in the activated state and does not form a stop for the coupling element in the deactivated state. For this purpose, it can be particularly preferably provided that when the stop element is deactivated, the coupling element is moved so far into the coupling gap as a result of an elastically unloaded state or a constructive elastic loading that (if necessary in conjunction with a self-reinforcing effect of the coupling device) the eccentric sleeve from the Crankshaft taken along and thus rotated relative to the connecting rod eye, while one activated stop element, a portion of the coupling element that strikes this as a result of the rotation of the eccentric sleeve leads to the fact that it is led out of the narrowing coupling gap to such an extent that the eccentric sleeve is no longer entrained by the crankshaft and, in particular, essentially no relevant friction between the coupling surfaces the eccentric sleeve and the crankshaft on the one hand and the coupling element on the other hand is more given.

In a preferred embodiment of the internal combustion engine according to the invention it can be provided that the coupling element forms coupling surfaces which are (in each case) aligned parallel to the coupling surfaces of the crankshaft and the eccentric sleeve. As a result, an advantageous non-positive effect can be achieved between the coupling surfaces interacting in each case.

Furthermore, it can preferably be provided that a (preferably positive-locking) locking element of the locking device also serves as a stop element of the coupling device. This can be particularly useful if, by means of the stop element, the coupling device is to be released (i.e. a reduction or elimination of the non-positive effect), because in the internal combustion engine according to the invention, this occurs simultaneously with a locking of the eccentric sleeve in one of the rotary orientations caused by the locking device of the connecting rod. Accordingly, a constructively advantageous double function can be implemented for the locking element.

Furthermore, it can be provided for the internal combustion engine according to the invention that a locking element (preferably displaceably mounted on the connecting rod) of the locking device can be moved into a locking recess of the connecting rod or (preferably) of the eccentric sleeve, the locking recess with respect to an orbit of the locking element on which the locking element relative to the component forming the locking recess during a relative rotation between the eccentric sleeve and the connecting rod, has a (preferably at least 50%, particularly preferably at least 100%) larger dimension than the part of the locking element provided for engaging in the locking recess. The term “locking recess” is also intended to cover through openings into which the locking element or at least a part thereof can engage in order to form a positive locking. Such a locking recess, which is relatively large with respect to the orbit of the locking element, can ensure secure engagement of the locking element even at high relative angular velocities between the locking element and the component forming the locking recess.

In order to avoid or restrict mobility between the locking element or the component carrying the locking element (in particular the connecting rod) and the component forming the locking recess (in particular the eccentric sleeve) when the locking element engages in the locking recess despite such a relatively large locking recess, it is preferably further possible a non-return element can be provided, which can engage together with the blocking element in the blocking recess and can thereby fill a section of the blocking recess in which the blocking element is not arranged after engaging in the blocking recess. It can also be provided that the locking element and the anti-return element, if they both engage in the locking recess, do not completely fill the locking recess because a distance is formed between them. The locking element then prevents a relative rotation of the eccentric sleeve to the connecting rod in one of the directions of rotation by striking at one end (with respect to the extension along the orbit) of the locking recess and the backstop element prevents a relative rotation in the other direction of rotation by striking the corresponding other end of the blocking recess.

In order to achieve an automatic function of the backstop element, it can be provided that it is bevelled on the side facing the blocking element in such a way that it can be moved out of the blocking recess as a result of contact with the edge of the blocking recess, whereby this movement further preferably leads to a ( increasing) preload of a spring element leads. This pretensioning of the spring element can then ensure a renewed engagement of the anti-return element in the / a locking recess if the latter is positioned again or another locking recess as a result of a rotation of the eccentric sleeve corresponding to the anti-return element.

In a preferred embodiment of an internal combustion engine according to the invention with an active setting device, at least two coupling devices can be provided, the second (in particular released) position of the coupling element of a first of the coupling devices being adjustable by means of the setting device in a first rotational orientation of the eccentric sleeve with respect to the connecting rod, and the second (in particular released) position of the coupling element of a second of the coupling devices can be adjusted by means of the adjusting device in a second rotational orientation of the eccentric sleeve with respect to the connecting rod. Such a configuration can simplify and in particular make it possible to prevent or prevent entrainment of the eccentric sleeve by the crankshaft in the at least two rotational orientations or from these rotational orientations enable by a comparatively simple locking and / or adjusting device.

In particular, this can also make it possible for a (possibly serving as a stop element) first locking element of the locking device, by means of which the eccentric sleeve can be locked in a first rotational orientation with respect to the connecting rod, and a (optionally serving as a stop element) second locking element of the locking device, by means of which the Eccentric sleeve can be locked in a second rotational orientation with respect to the connecting rod, can be actuated alternately by means of a common actuating element.

The actuating element can preferably be designed such that it can be pivoted about a pivot pin which is part of a screw connection with which two parts of the connecting rod forming the connecting rod eye are connected. The actuating element would then be part of the connecting rod and would be moved with it during operation of the internal combustion engine. By using a screw connection with which a connecting rod eye, which is divided into two in a known manner, is used as a rotary bearing element for the actuating element, an additional mass resulting from the integration of the actuating element in the connecting rod can be kept low.

In a further preferred embodiment of the internal combustion engine according to the invention it can also be provided that the actuating element also serves as a stop element of the coupling devices, by means of which the coupling elements can preferably be moved into the respective position corresponding to a released state of the associated coupling device. This double function for the actuating element can lead to a relatively simple structural design of the internal combustion engine according to the invention.

In particular, in order to lock the eccentric sleeve as securely as possible in one of the rotational orientations with respect to the connecting rod, it can be provided that the actuating element can be secured in position in two actuating end positions by means of a detent. This detent device is preferably designed in such a way that it can be released by an active action with the aim of switching the actuating element by only applying a force, but forces are required for this which do not act on the actuating element in the corresponding direction during normal operation of the internal combustion engine ,

The actuating element can preferably be actuated by means of an actuating rail. An “actuating rail” is understood to mean a guide element that is positioned or positionable in such a way that the actuating element is moved at least in sections along the crankshaft with each revolution, said actuating element being movable from a first position to a second position for actuating the actuating element. After such a movement of the actuating rail, a subsequent moving along of the actuating element leads to contact with a guide surface of the actuating rail, as a result of which the actuating element is displaced or pivoted and thereby switched over. For this purpose, the actuating rail can preferably be fastened to a housing of the internal combustion engine or is at least not moved along with the crankshaft or the connecting rod as a result of a different type of fastening, so that the actuating rail does not result in an increase in masses moved for the operation of the internal combustion engine. It can particularly preferably be provided that the actuating rail is pivotally attached to, in particular, a housing of the internal combustion engine, because compared to a likewise possible embodiment with an actuating rail that is displaceably attached to the housing, simplified actuation by means of an actuator rail (for example hydraulic, pneumatic, electromotive or electromagnetic) actuator can be made possible.

For actuation of the actuating element by the actuating rail as smoothly as possible, it can preferably be provided that the actuating rail forms a guiding groove for the actuating element that tends to be curved (i.e. narrowing) on both sides. The arch shape can preferably be designed such that the direction of movement of the actuating element, as long as it is moved along the actuating rail, is oriented as tangentially as possible at any time.

Furthermore, it can preferably be provided that the latching device for the actuating element, which is preferably provided in the internal combustion engine according to the invention, is designed such that the actuating element does not contact the actuating rail in the actuating end positions. Frictional losses due to cyclical grinding of the actuating element along the guide rail when the actuating element is in one of its actuating end positions (which can always be the case when the compression ratio of the internal combustion engine is not being switched over, and thus during most of the operating time of the internal combustion engine) , can be avoided, which is not only positive for the wear of the actuating element and the actuating rail but can also affect the acoustic behavior of the internal combustion engine.

• in der ersten Drehausrichtung der Exzenterhülse bezüglich des Pleuels, in der die zweite Stellung des Kupplungselements der ersten Kupplungsvorrichtung mittels der dazugehörigen Einstellvorrichtung eingestellt ist, die zweite Stellung des Kupplungselements der zweiten Kupplungsvorrichtung mittels eines passiven Einstellelements eingestellt ist und
• in der zweiten Drehausrichtung der Exzenterhülse bezüglich des Pleuels, in der die zweite Stellung des Kupplungselements der zweiten Kupplungsvorrichtung mittels der dazugehörigen Einstellvorrichtung eingestellt ist, die zweite Stellung des Kupplungselements der ersten Kupplungsvorrichtung mittels eines passiven Einstellelements eingestellt ist.

Dadurch wird insbesondere ermöglicht, dass in jeder der Drehausrichtungen lediglich eine der Kupplungsvorrichtungen aktiv beeinflusst werden muss, um diese geöffnet zu halten oder zu schließen, während die andere Kupplungsvorrichtung durch das passive Einstellelement ausschließlich infolge der jeweiligen Drehausrichtung der Exzenterhülse selbsttätig offen gehalten wird. Wird dann die in der jeweiligen Drehausrichtung aktiv beeinflusste Kupplungsvorrichtung geschlossen, kann die durch diese Kupplungsvorrichtung bewirkte Mitnahme der Exzenterhülse (in einem relativ kleinen Winkelbereich der Drehung der Exzenterhülse bezüglich des Pleuels) zu einem Überwinden des die andere Kupplungsvorrichtung offen haltenden passiven Einstellelement bewirken, so dass anschließend beide Kupplungsvorrichtungen das Mitnehmen der Exzenterhülse durch die Kurbelwelle sicherstellen, bis die entsprechende andere Drehausrichtung erreicht ist. Dann kann die zuvor mittels des passiven Einstellelements offen gehaltene Kupplungsvorrichtung aktiv beeinflusst werden, während die zuvor aktiv beeinflusste Kupplungsvorrichtung durch das dazugehörige passive Einstellelement offen gehalten wird.In a particularly preferred embodiment of an internal combustion engine according to the invention provided with at least two coupling devices, it can be provided that

• in the first rotational orientation of the eccentric sleeve with respect to the connecting rod, in which the second position of the coupling element of the first coupling device is set by means of the associated setting device, the second position of the coupling element of the second coupling device is set by means of a passive setting element and
• in the second rotational orientation of the eccentric sleeve with respect to the connecting rod, in which the second position of the coupling element of the second coupling device is set by means of the associated setting device, the second position of the coupling element of the first coupling device is set by means of a passive setting element.

This makes it possible in particular that only one of the coupling devices has to be actively influenced in each of the rotational orientations in order to keep them open or closed, while the other coupling device is automatically kept open by the passive adjusting element solely as a result of the respective rotational orientation of the eccentric sleeve. If the coupling device which is actively influenced in the respective rotational alignment is then closed, the entrainment of the eccentric sleeve caused by this coupling device (in a relatively small angular range of the rotation of the eccentric sleeve with respect to the connecting rod) can result in overcoming the passive adjusting element which keeps the other coupling device open, so that then both coupling devices ensure that the eccentric sleeve is carried along by the crankshaft until the corresponding other rotational alignment is achieved. Then the clutch device previously kept open by means of the passive adjusting element can be actively influenced, while the previously actively influenced clutch device is kept open by the associated passive adjusting element.

• in einer der Drehausrichtungen der Exzenterhülse relativ zu dem Pleuel das zweite Sperrelement mittels des Betätigungselements in einer Lösestellung gehalten wird, während das erste Sperrelement mittels eines zwischen den Sperrelementen abgestützten Federelements in eine (die Exzenterhülse in einer der Drehausrichtungen sperrenden) Sperrposition beaufschlagt ist und
• in einer/der anderen Drehausrichtung der Exzenterhülse relativ zu dem Pleuel das erste Sperrelement mittels des Betätigungselements in einer Lösestellung gehalten wird, während das zweite Sperrelement mittels des Federelements in eine Sperrposition beaufschlagt ist.

Dadurch kann eine konstruktiv vorteilhafte Ausgestaltung für das zur Betätigung beider Sperrelemente vorgesehene Betätigungselement erreicht werden.In a further preferred embodiment of an internal combustion engine according to the invention with (at least) two locking elements which can be actuated alternately by a common actuating element, it can also be provided that

• in one of the rotational orientations of the eccentric sleeve relative to the connecting rod, the second locking element is held in a release position by means of the actuating element, while the first locking element is supported by means of one between the locking elements Spring element is in a (the eccentric sleeve in one of the rotational orientations blocking) locked position and
• in one / the other rotational orientation of the eccentric sleeve relative to the connecting rod, the first locking element is held in a release position by means of the actuating element, while the second locking element is urged into a locking position by means of the spring element.

As a result, a structurally advantageous configuration for the actuating element provided for actuating both locking elements can be achieved.

The indefinite articles ("a", "an", "one" and "one"), particularly in the
Claims and in the description generally describing the claims are to be understood as such and not as numerals. Correspondingly concretized components are to be understood in such a way that they are present at least once and can be present several times.

Fig. 1:

einen teilweisen perspektivischen Querschnitt durch die relevanten Komponenten einer erfindungsgemäßen Brennkraftmaschine in einer ersten Ausführungsform;

Fig. 2:

in isolierter Darstellung die für eine Veränderung der Verdichtung der Brennkraftmaschine relevanten Komponenten in einer perspektivischen Ansicht;

Fig. 3:

die Komponenten gemäß der Fig. 2 in einer weiteren perspektivischen Ansicht;

Fig. 4:

die Komponenten gemäß den Fig. 2 und 3 (jedoch ohne Betätigungsschiene der Brennkraftmaschine) in einer weiteren perspektivischen Ansicht;

Fig. 5:

die Komponenten gemäß der Fig. 4 in einer weiteren perspektivischen Ansicht;

Fig. 6:

die Komponenten gemäß den Fig. 4 und 5 in einer weiteren perspektivischen Ansicht;

Fig. 7:

in einem Ausschnitt eine Ansicht von unten auf die Komponenten gemäß den Fig. 4 bis 6 mit einem Betätigungselement der Brennkraftmaschine in einer ersten Betätigungsendstellung;

Fig. 8:

einen Radialschnitt durch einen Abschnitt einer Kurbelwelle, eines Pleuels, einer Exzenterhülse, einer Einstell- und einer Sperrvorrichtung sowie zwei Kupplungsvorrichtungen der Brennkraftmaschine, wobei sich ein erstes Sperrelement der Sperrvorrichtung in einer Sperrstellung und ein zweites Sperrelement der Sperrvorrichtung in einer Lösestellung befindet;

Fig. 9:

eine Ansicht gemäß der Fig. 7 mit dem Betätigungselement in einer zweiten Betätigungsendstellung;

Fig. 10:

eine Ansicht gemäß der Fig. 8, wobei sich nunmehr jedoch das erste Sperrelement in einer Lösestellung und das zweite Sperrelement in einer Zwischenstellung befindet;

Fig. 11:

eine Ansicht gemäß der Fig. 10, wobei sich nunmehr jedoch das zweite Sperrelement in einer Sperrstellung befindet;

Fig. 12:

einen Querschnitt durch die Komponenten gemäß den Fig. 7 bis 11;

Fig. 13:

in isolierter Darstellung das Betätigungselement der Brennkraftmaschine in einer perspektivischen Ansicht;

Fig. 14:

einen teilweisen perspektivischen Querschnitt durch die relevanten Komponenten einer erfindungsgemäßen Brennkraftmaschine in einer zweiten Ausführungsform;

Fig. 15:

den Kurbeltrieb der Brennkraftmaschine gemäß der Fig. 14 in einer Seitenansicht;

Fig. 16:

den in der Fig. 15 mit XVI gekennzeichneten Ausschnitt in vergrößerter und teilweise geschnittener Darstellung;

Fig. 17:

in isolierter Darstellung die für eine Veränderung der Verdichtung der Brennkraftmaschine relevanten Komponenten (mit Ausnahme der Kurbelwelle) der Brennkraftmaschine gemäß der Fig. 14 in einer perspektivischen Ansicht; und

Fig. 18:

die Komponenten gemäß der Fig. 17 in einer weiteren perspektivischen Ansicht.

The present invention is explained in more detail below on the basis of exemplary embodiments illustrated in the drawings. In the drawings:

Fig. 1:

a partial perspective cross section through the relevant components of an internal combustion engine according to the invention in a first embodiment;

Fig. 2:

in an isolated representation, the components relevant for changing the compression of the internal combustion engine in a perspective view;

Fig. 3:

the components according to the Fig. 2 in a further perspective view;

Fig. 4:

the components according to the 2 and 3 (but without the operating rail of the internal combustion engine) in a further perspective view;

Fig. 5:

the components according to the Fig. 4 in a further perspective view;

Fig. 6:

the components according to the 4 and 5 in a further perspective view;

Fig. 7:

in a detail a bottom view of the components according to the 4 to 6 with an actuating element of the internal combustion engine in a first actuation end position;

Fig. 8:

a radial section through a section of a crankshaft, a connecting rod, an eccentric sleeve, an adjusting and a locking device and two coupling devices of the internal combustion engine, wherein a first locking element of the locking device is in a locking position and a second locking element of the locking device is in a release position;

Fig. 9:

a view according to the Fig. 7 with the actuating element in a second actuating end position;

Fig. 10:

a view according to the Fig. 8 , but now the first locking element is in a release position and the second locking element is in an intermediate position;

Fig. 11:

a view according to the Fig. 10 , but now the second locking element is in a locking position;

Fig. 12:

a cross section through the components according to the 7 to 11 ;

Fig. 13:

in an isolated representation, the actuating element of the internal combustion engine in a perspective view;

Fig. 14:

a partial perspective cross section through the relevant components of an internal combustion engine according to the invention in a second embodiment;

Fig. 15:

the crank mechanism of the internal combustion engine according to the Fig. 14 in a side view;

Fig. 16:

the one in the Fig. 15 XVI marked section in an enlarged and partially sectioned representation;

Fig. 17:

The components relevant to a change in the compression of the internal combustion engine (with the exception of the crankshaft) of the internal combustion engine according to the Fig. 14 in a perspective view; and

Fig. 18:

the components according to the Fig. 17 in another perspective view.

The 1 to 13 show an internal combustion engine according to the invention, for example an Otto or diesel engine, in a first embodiment. According to the Fig. 1 on Cylinder crankcase 10, within which one or more cylinders 12 are formed. On the one in the Fig. 1 The upper end of the cylinder crankcase 10 is adjoined by a cylinder head, not shown, while the lower end of the cylinder crankcase 10 is provided for connection to an oil pan, also not shown. A crankshaft space 16 which accommodates a crankshaft 14 of the internal combustion engine would then be designed to be essentially completely closed.

Within the (or each) cylinder 12, a piston 18 is axially movable (with respect to a longitudinal axis 20 of the cylinder 12 and the piston 18). An upper side of the piston 18, the so-called piston crown, delimits a combustion chamber with the cylinder head, in which a fuel / fresh gas mixture is burned during an operating cycle in the operation of the internal combustion engine in order to perform work. An increase in pressure within the combustion chamber as a result of the combustion leads, in a known manner, to a downward movement of the piston 18, which is translated by means of a connecting rod 22 into a rotary movement of the crankshaft 14 rotatably mounted within the cylinder crankcase 10. For this purpose, the upper end of the connecting rod 22 is pivotally mounted on the piston 18, for which purpose the connecting rod 22 has a first, so-called small connecting rod eye 38 (cf. Fig. 15 ) forms, which rotatably receives a piston pin 24 of the piston 18. Furthermore, the lower end of the connecting rod 22 is equipped with a so-called large connecting rod eye 26 (cf. for example Fig. 2 ) rotatably mounted on a crank pin 30 arranged decentrally with respect to an axis of rotation 28 of the crankshaft 14 (cf. in particular Fig. 15 ), so that the pressure forces acting on the piston crown, which are transmitted to the crank pin 30 via the connecting rod 22, generate a torque about the axis of rotation 28 of the crankshaft 14.

How this is particularly evident from the Fig. 15 results, such a crankshaft 14 comprises cylindrical bearing sections 32 which are arranged coaxially with respect to the axis of rotation 28 of the crankshaft 14 and on the one hand the connection of adjacent crankpins 30 (in a multi-cylinder internal combustion engine) to one another and on the other hand at least partially the rotatable mounting of the crankshaft 14 within the Serve cylinder crankcase 10. The crank pins 30 which are rotatably mounted within the large connecting rod eyes 26 of the connecting rods 22 are delimited on both sides by disk-shaped sections of the crankshaft which, on the one hand, form the so-called crank webs 34, which connect the crank pins 30 to the bearing sections 32, and on the other hand, the crank webs 34 with respect to Form axis of rotation 28 radially opposite balancing masses 36, whereby free mass forces and mass moments are to be avoided as possible when rotating the crankshaft 14.

To the compression ratio during operation of the internal combustion engine, i.e. the ratio of the volume of the combustion chamber at the bottom dead center of the piston 18 to the volume at the top dead center of the piston 18 can be changed in two stages, the crank pin (s) 30 with the interposition (in each case) of an eccentric sleeve 40 within the large one Conrod eyes / conrod eyes 26 to store. The (each) eccentric sleeve 40 comprises a tubular bearing section 42, the cylindrical inner surface of which serves as a sliding surface for the rotary mounting of the crank pin 30 accommodated therein and the cylindrical outer surface of which serves as a sliding surface for the rotary mounting of the eccentric sleeve 40 within the large connecting rod eye 26 of the associated connecting rod 22. The inner and outer surfaces of the bearing section 42 are not coaxially but radially offset from one another by a defined distance, as a result of which the distance between the pivot or rotation axis 44 of the small connecting rod eye and the axis of rotation 46 of the cylindrical inner surface of the eccentric sleeve and thus the distance between the piston 18 and the associated crank pin 30 changes depending on the rotational orientation of the eccentric sleeve 40 within the large connecting rod eye 26.

At the two longitudinal axial ends, the tubular bearing section 42 of the eccentric sleeve 40 merges into a delimiting section 48, which is formed in each case by an annular disk which extends radially outward from the bearing section 42 and thereby allows the eccentric sleeve 40 to move within the large connecting rod eye 26 limited in the axial direction with respect to the longitudinal axis 50 of the large connecting rod eye 26.

By means of a locking device 52, the rotatability of the eccentric sleeve 40 within the large connecting rod eye 26 of the connecting rod 22 can be locked in two defined rotational directions, it being provided in the present exemplary embodiment that the two rotational directions have the smallest and the largest distance between the piston 18 and the associated crank pin 30 correspond.

As can be seen in particular from the 8 to 11 results, the locking device 52 comprises two locking elements 56, which are coaxially aligned with one another and slidably arranged within a cylindrical receiving opening 54 of the connecting rod 22. The receiving opening 54 is arranged at the outermost end of the connecting rod 22 (forming the large connecting rod eye 26) and thus in the extension of a connecting rod shaft 58 of the connecting rod 22 positioned. In particular, it can be provided that the longitudinal axis 60 of the connecting rod 22 passes through the receiving opening 54 and in particular also crosses the longitudinal axis of the receiving opening 54. Between The two locking elements 56 is a prestressed spring element 62 in the form of a cylindrical helical spring, which acts on the two locking elements 56 away from each other and thus in the direction of the associated end of the receiving opening 54 or in the direction of the adjoining limiting section 48 of the eccentric sleeve 40.

The axial mobility of the locking elements 56 within the receiving opening 54 is variably limited depending on the position of an actuating element 64. For this purpose, a catch projection 66 of the in the Fig. 13 Actuating element 64 shown in isolation in a driving groove 68 of the blocking elements 56 (with respect to the longitudinal axis of the receiving opening 54 or the movement axis of the blocking elements 56), which on the one hand limits the mobility of the blocking elements 56 within the receiving opening 54 and on the other hand for a change in the compression ratio , in which the internal combustion engine can be operated, can be displaced within the receiving opening 54 by switching the actuating element 64 between two actuation end positions.

The 7 and 8 show the actuating element 64 in a first actuating end position, in which a first of the locking elements 56, which in the Fig. 8 . 10 and 11 is shown on the right, in a through opening (corresponding to the configuration according to the 7 to 11 ) or recess on the edge (corresponding to the configuration according to 1 to 6 ) can engage in the associated limiting section 48 of the eccentric sleeve 40 formed locking recess 70, provided that the eccentric sleeve 40 is in the corresponding rotational orientation with respect to the connecting rod 22 or the large connecting rod eye 26. The Fig. 9 and 11 on the other hand show the actuation element 64 in the second actuation end position, in which the second of the locking elements 56, which in the Fig. 8 . 10 and 11 is shown on the left, can engage in such a locking recess 70 formed in the associated limiting section 48 of the eccentric sleeve 40 if the eccentric sleeve 40 is in the associated rotational orientation, which is relative to the first rotational orientation of the eccentric sleeve 40 (according to FIGS Fig. 8 and 10 ) is offset by approx. 180 °. In these two rotational orientations of the eccentric sleeve 40, which can be locked by means of the locking device 52, the distances between the piston 18 and the associated crank pin 30 differ due to the eccentric design of the eccentric sleeve 40. These different distances are also made from a comparison of the Fig. 8 and 11 can be seen from which the different wall thicknesses of the tubular bearing section 42 of the eccentric sleeve 40 in the section between the crank pin 30 and the Locking device 52 receiving portion of the connecting rod 22 can be seen. In the direction of rotation according to the Fig. 8 the wall thickness of the corresponding area of the bearing section 42 of the eccentric sleeve 40 is greater than in the rotational orientation according to FIG Fig. 11 , whereby the distance between the crank pin 30 and the piston 22 in the rotational orientation according to the Fig. 8 smaller than that in the rotational orientation according to the Fig. 11 is.

The Fig. 10 shows the positions of the locking elements 56 after switching the actuating element 64 from the one in FIG Fig. 7 shown first actuation end position in the, inter alia, in the Fig. 9 shown second actuation end position, but before the eccentric sleeve 40 from the rotational alignment according to the Fig. 8 in the direction of rotation according to the Fig. 11 has been rotated. In the Fig. 10 it is shown that the first locking element 56, shown on the right, is in a release position in which it is disengaged from the associated locking recess 70 of the eccentric sleeve 40 and also at a defined distance from the associated limiting section 48 of the eccentric sleeve 40. Moving the first locking element 56 shown on the right, starting from the locking position according to FIG Fig. 8 in the release position according to the Fig. 10 is achieved by switching the actuating element 64 starting from a first actuating end position according to FIG Fig. 7 in the second actuation end position according to the Fig. 9 reached, which is pivoted about a pivot axis 72. The corresponding driver projection 66 of the actuating element 64 takes the first locking element 56 with it as a result of contact with the inner boundary wall of the driver groove 68 and displaces it within the receiving opening 64 in the direction of its longitudinal axial center. At the same time, the second locking element 56, shown on the left, is given the possibility of moving further in the direction of the corresponding end of the receiving opening 64, this movement being prestressed by the one supported between the locking elements 56 and by the movement of the first locking element 56 in the direction of the longitudinal axis Spring element 62 further biased in the middle of the receiving opening 64. As long as the eccentric sleeve 40 is not yet in the Fig. 11 illustrated second rotational orientation has been rotated, this mobility of the second locking element 56 is limited as a result of contact with the inside of the associated limiting section 48 of the eccentric sleeve 40. Only shortly before reaching the second rotational alignment can the second locking element 56 engage in the correspondingly positioned corresponding locking recess 70 and thus in its side Fig. 11 shown locking position are moved.

When the actuating element 64 is switched over again, then from the position shown in FIG Fig. 9 shown second actuation end position in the Fig. 7 First actuation end position shown, the second locking element 56 is moved into the associated release position in a corresponding reverse order and the first locking element 56 is released, which in turn can engage in the associated locking recess 70 as soon as the eccentric sleeve again within the large connecting rod eye 26 by approximately 180 ° has been rotated.

The connecting rod 22 comprises two parts screwed together, one connecting rod base body 74 forming the small connecting rod eye 38, the connecting rod shaft 58 and one half of the large connecting rod eye 26, and a connecting rod cover 76 forming the second half of the large connecting rod eye 26 and integrating the locking device 52. This two-part connecting rod 22 in the area of the large connecting rod eye 26 enables the connecting rod 22 to be connected to the corresponding bearing journal 30 of the one-piece crankshaft 14 during the assembly of the internal combustion engine. The parting plane between the connecting rod base body 74 and the connecting rod cover 76 runs perpendicular to the longitudinal axis 60 of the connecting rod 22 (or the connecting rod shaft 58). Furthermore, the axis of rotation 50 of the eccentric sleeve 40 also runs within the large connecting rod eye 26 within this parting plane, which results in a radial alignment of this parting plane with respect to the large connecting rod eye 26. As it is particularly in the Fig. 12 As can be seen, the screw of one of the screw connections 78 between the connecting rod base body 74 and the connecting rod cover 76 is used as a pivot pin for the actuating element 64. The pivot axis 72, about which the actuating element 64 can be pivoted in order to be moved back and forth between its two actuation end positions, thus corresponds to the longitudinal axis of the screw of this screw connection 78.

The actuating element 64 is secured in its two actuating end positions by means of a detent 80, which according to FIGS 12 and 13 is formed by a detent ball 84 movably guided by a spring element 82 in a guide opening of the connecting rod 22 or the connecting rod cover 76 in connection with one of two bowl-shaped detent recesses 86 arranged next to one another, which are integrated in the adjacent section of the actuating element 64. When the actuating element 64 is switched over between its actuating end positions, the latching ball 84 must be raised with further prestressing of the associated spring element 82 in order to overcome the web 88 arranged between the two latching depressions 86. For this purpose, a switchover torque (about the pivot axis 72 of the actuating element 64) is required, which is not caused by forces that usually occur during operation of the internal combustion engine becomes. An unintentional, automatic switching of the actuating element 64 can thus be avoided by the catch 80. On the other hand, all that is required for a switchover is to apply a corresponding switchover torque to the actuating element 64, without having to release a form-locking lock.

The actuating element 64 is actuated by means of an actuating rail 90 which is pivotally attached to the cylinder crankcase 10, as is shown in FIGS 1 to 3 is shown. The actuating rail 90 is in the Fig. 1 shown in the manner of an exploded view at a distance from the connection point on the cylinder crankcase 10 and thus from its actual functional position within the crankshaft space 16. In its actual functional position (cf. 2 and 3 ), the actuating rail 90 is so close to the axis of rotation 28 of the crankshaft 14 that the actuating element 64 connected to the connecting rod 22 with a guide element 92 formed by it is in the position corresponding to the bottom dead center of the piston 18 and at least over a defined angular range in front of the Reaching this position is arranged within a guide groove 94 formed by two side walls of the actuating rail. The width of the guide groove 94 decreases continuously from an inlet, ie the end at which the guide element 92 of the actuating element 64 enters the guide groove 94 in the course of each revolution of the crankshaft 14. In addition, the longitudinal extent of the actuating rail 90 is adapted to the orbit of the guide element 92 of the actuating element 64, which describes this as a result of one revolution of the crankshaft 14, by means of a curved course, so that in particular it can be provided that a distance between the underside of the guide element 92 to the groove bottom 96 of the guide groove 94 of the actuating rail 90, remains essentially the same over the course of the movement of the guide element 92 within the guide groove 94. It is preferably provided that the guide element 92 of the actuating element 64 does not contact the groove base 96 of the guide groove 94 at any time.

If the actuating element 64 is in one of its actuating end positions and the actuating rail 90 is in the associated functional position, the guide element 92 of the actuating element 64 becomes contactless with each revolution of the crankshaft 14 without contact with one of the inner guide surfaces 98 of the guide groove 94 formed by the side walls of the actuating rail 90 Actuating rail 90 passed through the guide groove 94. In particular, it can be provided that the guide element 92, at least at the end of the guide groove 94, is essentially exactly centered between the two Side walls is guided. If, on the other hand, starting from such a starting position, the actuating rail 90 is pivoted into the corresponding other functional position by means of an actuator, not shown, which is also controlled by a motor control of the internal combustion engine, the guide element 92 of the actuating element 64 contacts the next time it enters the guide groove 94 by the Actuation of the actuation rail 90 into the guide surface 98 moved into the orbit of the guide element 92, so that the guide element 92 is guided along this guide surface 98 and the actuation element 64 is moved or pivoted in the direction of its other actuation end position due to the narrowing guide groove 94. The pivoting movement of the actuating element 64 caused by the contact with the corresponding guide surface 98 is only so great that the latching ball 84 of the latching safety device 80 is moved over the web 88 formed between the two latching depressions 86. The last, relatively small section of the pivoting movement of the actuating element 64 into its actuating end position, which is then provided, is achieved by latching the latching ball 84 into the corresponding latching recess 88. This can cause the guide element 92 of the actuating element 64 to be moved a little further away from the guide surface 98 of the actuating rail 90 which brings about the switchover, and thus there is no contact with this or with both side walls of the actuating rail 90 during the subsequent operation of the internal combustion engine.

The guide surfaces 98 of the actuating rail 920 are curved such that the guide element 92 of the actuating element 64 runs after the actuating rail 90 has been switched over in the tangential direction onto the corresponding guide surface 98, as a result of which the actuating element 64 can be switched over with a force curve that increases as uniformly as possible. This can have an advantageous effect on the service life of the components involved and on the acoustic behavior of the internal combustion engine.

In order to enable safe and rapid rotation of the eccentric sleeve 40 between the two rotational orientations which can be locked by the locking device 52 after the actuating element 64 has been pivoted from one of the actuating end positions into the other of the actuating end positions by means of the actuating rail 90, the internal combustion engine according to the invention comprises two non-positive coupling devices 100 , by means of which the eccentric sleeve 40 can be temporarily coupled to the crankshaft 14 in order to rotate the eccentric sleeve 40 relative to the connecting rod 22 or the large connecting rod eye 26. Each of the coupling devices 100 includes one Crescent-shaped or partially ring-shaped coupling element 102, which is arranged on the outside of one of the limiting sections 48 of the eccentric sleeve 40 and thus in a coupling gap 104 formed between the eccentric sleeve 40 and the adjacent crank arm 34 of the crankshaft 14. An end section of the coupling element 102 is rotatably fastened in the associated limiting section 48 of the eccentric sleeve 40, and the coupling element extends from this rotary bearing in the direction of rotation 106 of the eccentric sleeve, which relative to the latter during operation of the internal combustion engine (and in the event of a lock in one of the rotating directions) to the associated crank webs (cf. 2 and 3 ).

How, for example, from the Fig. 8 . 10 and 11 results, the gap width of the coupling gap 104 decreases in the radial direction towards the outside, which is due to a corresponding inclination of the inside of the crank arms 34 serving as coupling surfaces (facing the eccentric sleeve 40) by an angle of approximately 3 ° with respect to an orientation that is perpendicular to the axis of rotation 50 of the eccentric sleeve 40 within the large connecting rod eye 26 or the axis of rotation 46 of the crank pin 30 within the eccentric sleeve 40 is reached. The cross-section of each of the coupling elements 102 is correspondingly tapered or wedge-shaped, so that there is a parallel alignment of the coupling surfaces of the coupling elements 102 with the coupling surfaces formed by the crank cheeks 34. The coupling elements 102 of both coupling devices 100 are each acted upon by a prestressed spring element 108 in the radially outward direction and thus into the coupling gap 104, which is becoming narrower. This spring loading leads to initial loads for the coupling devices 100, by means of which the coupling surfaces of the coupling elements 102 are pressed against the coupling surfaces of the crank webs 34 and the eccentric sleeve 40 (which are formed by the outer sides of the limiting sections 48 of the eccentric sleeve 40). The output loads generated in this way lead to frictional forces which are opposite to a relative movement between the eccentric sleeve 40 and the crank webs 34 and whose direction of action is such that this additionally provides a moment about the respective rotary mounting of the coupling elements 102 in the direction of further pivoting outwards and thus an additional one Pull into the respective narrowing coupling gap 104. A self-reinforcement of the non-positive effects of the coupling devices 100 in the respective closed state is thereby achieved.

During operation of the internal combustion engine and when the eccentric sleeve 40 is locked in one of the rotational orientations, the coupling devices 100 are usually opened by the Coupling elements 102 are each pivoted inward by contact with a stop element 110 to the extent that the respective spring element 108 is further pretensioned, so that the least possible frictional connection between at least the coupling surfaces of the crank arms 34 and the adjacent coupling surfaces of the coupling elements 102 is provided. The coupling element 102, which is rotatably mounted on the limiting section 48 of the eccentric sleeve 40, into which the associated locking element 56 engages in the locking recess 70 as a result of the appropriately selected actuation end position of the actuating element 64, is deflected inwards by means of an associated stop element 110 of the actuating element 64 is carried out while the other coupling element 102 is deflected by means of a passive, immovable stop element 110.

If the actuating element 64 is now switched over, the coupling element 102 previously deflected by it is released, so that it swings outwards due to the spring load and thus into the associated narrowing coupling gap 104, whereby at least the corresponding coupling device 100 is closed. This closed coupling device 100 then initially alone causes the eccentric sleeve 40 to rotate with the crank cheeks 34 rotating relative to the large connecting rod eye 26. This rotating action causes the other coupling element 102 to be released from the deflecting contact with the passive stop element 110, so that this coupling element subsequently also 102 pressed into the narrowing coupling gap 104 as a result of the spring load, and thus this coupling device 100 is also closed. For the rest of the rotation of the eccentric sleeve through 180 ° into the other rotational alignment, both coupling devices 100 then effect the non-positive coupling of the eccentric sleeve 40 to the associated crank arms 34 of the crankshaft 14. Shortly before the new rotational alignment of the eccentric sleeve 40 is reached, the other locking element then engages 56, as already based on the Figures 10 and 11 described, into the locking recess 70 of the associated limiting section 48 of the eccentric sleeve 40 and the coupling elements 102 of both coupling devices 100 then run onto the corresponding stop elements 110, on the one hand the second stop element 110 of the actuating element 64 disengaged as a result of the switching of the actuating element 64, and on the other hand again the passive stop element 110 projecting over the eccentric sleeve 40 on both sides, which in turn pivots inward under renewed prestressing of the spring elements 108 and thus the coupling devices 100 are released. The internal combustion engine can then continue to be operated with a changed compression ratio, the eccentric sleeve 40 in the new rotational orientation compared to the Conrod 22 is locked and due to the disengaged coupling devices 100 again largely frictionless relative to the crank arms 34 is rotated.

As a result of the high speeds at which internal combustion engines, which are provided, for example, for driving motor vehicles, are operated, high differential angular velocities result between the eccentric sleeve 40 temporarily coupled to the crank arms 34 by means of the coupling devices 100 and the connecting rod 22 integrating the locking device 52 To ensure that these high differential angular velocities securely engage the respective spring-loaded locking element 56 pressed against the inside of the associated limiting section 48 of the eccentric sleeve 40 during the change of the rotational orientation, each of the locking recesses 70 has an orbit of the associated locking element 56 (with a rotation relative to the connecting rod 22) Eccentric sleeve 40) has a larger dimension than the part of the locking element 56 provided for engaging in the locking recess 70. For this purpose, the locking recesses 70 are designed as arcuate, elongated through openings or recesses. The locking elements 56 can thus engage not only in a specific rotational orientation but in a larger angular range in the associated locking recesses 70, so that this despite relatively high differential angular velocities and despite the inertia with which the locking elements 56 accelerate in the direction of the associated locking recesses 70 as a result of the spring load with sufficient certainty.

The larger dimensions of the locking recesses 70 compared to the parts of the locking elements 56 engaging in them, in spite of being locked by one of the locking elements 56, generally lead to (restricted) rotational mobility between the eccentric sleeve 40 and the large connecting rod eye 26. In order to eliminate or at least eliminate this rotational mobility To reduce as much as possible each locking element 56 is assigned a passive return locking element 112 attached to the connecting rod 22 and specifically to the connecting rod cover 76, which, when the associated locking element 56 is located at the front end with respect to the direction of rotation 106 of the eccentric sleeve 40 relative to the crank arms 34 of the associated locking recess 70 engages, likewise engages in this locking recess 70 in the region of the other end and thus, together with the locking element 56, connects the eccentric sleeve 40 to the connecting rod 22 largely without rotational play. Moving out a backstop element 112 engaging in a locking recess 70, even if the associated locking element 56 has been moved out of the associated locking recess 70 as a result of a switching of the actuating element 64, is automatically achieved in that the backstop elements 112 are each formed with an inclined surface, that when the eccentric sleeve 40 is then carried along by the crankshaft 14 when it comes into contact with the edge of the respective locking recess 70, it is deflected with further prestressing of a spring element 114. For a structurally advantageous integration of the two anti-return elements 112 in the connecting rod 22, it is provided that they are each attached to a free end of one leg of the spring element 114 designed in the form of a U-shaped leaf spring and the spring element 114 in the region of its arcuate section in which this is not deflected, is attached to the actuator 64.

Like the connecting rod 22 in the area of the large connecting rod eye 26, the eccentric sleeve 40 is also formed from two parts or half-shells, the parting plane 116 between these parts preferably being arranged such that the axis of rotation 46 of the crank pin 30 within the eccentric sleeve 40 or the axis of rotation 50 the eccentric sleeve 40 runs within the large connecting rod eye 26 within this parting plane 116. For the most advantageous mounting of the eccentric sleeve 40, it is further provided that bearing openings (and in particular the longitudinal axes thereof), which serve the rotary bearings of the coupling elements 102 in the associated delimiting sections 48 of the eccentric sleeve 40, are also arranged in this parting plane 116. The same applies to radially oriented guide openings 118 with respect to one of the axes of rotation 46, 50 of the eccentric sleeve for the deflectable ends of the spring elements 108 which are guided in an arc shape on the inside of the associated coupling elements 102 and are rotationally secured in the area of the rotary bearings of the coupling element. A separate connection of the two parts of the eccentric sleeve 40 is not necessary because these are held together due to the arrangement within the large connecting rod eye 26.

The in the 14 to 17 The illustrated second embodiment of an internal combustion engine according to the invention differs from the first embodiment according to the 1 to 13 essentially only with regard to the design of the coupling devices 100 and the setting device which can be actively influenced to release the coupling devices 100.

In this internal combustion engine, too, two non-positive coupling devices 100 are provided, each of which has a coupling element 102 which is elastically loaded into a position that closes the respective coupling device 100 and thus couples the eccentric sleeve 40 to a rotary movement of the crankshaft 14. While in the embodiment according to the 1 to 13 Coupling elements 102 are provided, which are acted upon by separate prestressed spring elements 108, are the coupling elements 102 in the embodiment according to FIGS 14 to 17 itself designed to be elastically deflectable. Specifically, these are each in the form of a spiral spring, one end of which engages in an opening in the associated delimiting section 48 of the eccentric sleeve 40 and is thereby secured in position, and which, starting from this end, rotates by more than 360 ° and specifically by approximately 450 ° the bearing opening formed by the eccentric sleeve 40 for the associated crank pin 30 of the crankshaft 14 is guided around. The second end of each of the spiral spring-shaped coupling elements 102 is angled and is supported with this angled section on the edge of the associated limiting section 48 of the eccentric sleeve 40. The geometry of the spiral spring-shaped coupling elements 102 is selected in such a way that when they are in contact with the angled ends at the edges of the delimiting sections 48, they are elastically expanded and thus pretensioned, which leads to the coupling elements 102 striving to curl closer or to a smaller diameter , This leads to a constructive elastic loading of the coupling elements 102, because they automatically move into the coupling gaps 104 which in this embodiment of the coupling devices 100 become narrower radially inwards (cf. Fig. 16 ) pull in and thereby bring about a force-locking coupling of the eccentric sleeve 40 to the crank webs 34, provided that these are not radially widened by hitting stop elements 110 and thus the non-positive connection between the coupling elements 102 and the coupling surfaces of the crank webs 34 and the eccentric sleeve 40 is canceled.

Another difference of the internal combustion engine according to the 14 to 18 to that according to the 1 to 13 lies in the fact that the activatable and deactivatable stop elements 110, one of which acts in one of the two rotational directions of the eccentric sleeve 40, which can be locked by means of the locking device 52, on one of the coupling elements 102, while at the same time the other coupling element 102 by contact with one passive stop element 110 is radially expanded (cf. Fig. 18 ), not by the actuating element 64 but by the respective blocking element 56. For this purpose, it is provided that the corresponding locking element 56, which also engages in the associated locking recess 70 of the eccentric sleeve 40, extends so far through the locking recess 70, which is designed as a through opening in the corresponding delimiting section 48 of the eccentric sleeve 40, into the associated coupling gap 104, so that at closed coupling devices 100 and thus when the eccentric sleeve 40 is taken along by the crankshaft 14 at the edge of the corresponding limiting section 48, the end of the corresponding coupling element 102 is supported when the corresponding eccentric sleeve 40 is rotated in the direction shown in FIGS Coupling gap 104 protruding part of the corresponding locking element 56 and thereby this coupling element 102 is expanded radially (cf. Fig. 17 ). At the same time, the corresponding end of the other coupling element 102 runs onto the associated passive stop element 110 on the outside and is also widened. Both clutch devices 100 are thus opened and a positive connection between the clutch elements 102 which are positively connected to the eccentric sleeve 40 and the crank webs 34 of the crankshaft 14 is essentially interrupted.

Starting from such a starting position, in which the internal combustion engine is operated with a constant compression ratio, the actuating element 64 is actuated by means of the actuating rail 90 in accordance with the procedure for the internal combustion engine according to FIGS 1 to 13 switched, the blocking element 56, which is in a locking position, is again first moved into a release position. Coupling element 102, which is then no longer widened by this locking element 56, then initially causes entraining of eccentric sleeve 40 by crankshaft 14, as a result of which, in a first, relatively small portion of the rotation of eccentric sleeve 40 relative to large connecting rod eye 26, also second coupling element 102 Engagement with the passive stop element 110 is brought. This second coupling element 102 then also couples the eccentric sleeve 40 to the associated crank arm 34 of the crankshaft 14. The second locking element 56, which then engages in the associated locking recess 70 when the eccentric sleeve 40 has reached the other rotational orientation, then expands the associated coupling element 102 radially, while the other coupling element 102 is radially expanded by the associated passive stop element 110, so that both coupling devices 100 are then opened again.

LIST OF REFERENCE NUMBERS

10

cylinder crankcase

12

cylinder

14

crankshaft

16

crankshaft space

18

piston

20

Longitudinal axis of the cylinder / piston

22

pleuel

24

piston pin

26

large connecting rod eye

28

Axis of rotation of the crankshaft

30

crank pin

32

Crankshaft bearing section

34

crank web

36

Compensating mass of the crankshaft

38

small connecting rod eye

40

eccentric

42

Storage section of the eccentric sleeve

44

Rotation axis of the small connecting rod eye

46

Rotation axis of the cylindrical inner surface of the eccentric sleeve

48

Limiting section of the eccentric sleeve

50

Longitudinal axis of the large connecting rod eye / axis of rotation of the cylindrical outer surface of the eccentric sleeve

52

locking device

54

Opening of the connecting rod

56

blocking element

58

connecting rod shaft

60

Longitudinal axis of the connecting rod

62

Spring element of the locking device

64

actuator

66

Carriage lead of the actuator

68

Driving groove of the locking element

70

blocking recess

72

Swivel axis of the actuator

74

Pleuelgrundkörper

76

connecting rod

78

Screw connection between the connecting rod base and the connecting rod cover

80

catch lock

82

Spring element of the locking device

84

Locking ball of the locking device

86

Locking recess of the locking device

88

Locking bar

90

balance rail

92

Guide element of the actuating element

94

Guide groove of the operating rail

96

Groove bottom of the guide groove

98

Guide surface of the guide groove

100

coupling device

102

coupling member

104

coupling gap

106

Direction of rotation of the eccentric sleeve relative to the crank arms

108

Spring element of the coupling device

110

stop element

112

Return member

114

Spring element for the backstop element

116

Parting plane between the parts of the eccentric sleeve

118

Guide opening for the spring element of the coupling device

Claims (19)

1. Combustion engine with a cylinder (12), a piston (18) guided in movement within the cylinder (12), a crankshaft (14) and a connecting rod (22) connecting the piston (18) to a crank pin (30) of the crankshaft (14), wherein inside the connecting rod end (26) of the connecting rod (22) an eccentric sleeve (40) is supported so that it can rotate accommodating the crank pin (30) so that it can rotate, which can be locked in at least two rotational alignments in relation to the connecting rod (22) by means of a locking device (52), and wherein a coupling device (100) is provided acting with a force fit, is connectable to the crankshaft (14) temporarily by means of the eccentric sleeve (40), to twist about the eccentric sleeve (40) relative to the connecting rod (22), characterised in that the crankshaft (14) and the eccentric sleeve (40) respectively exhibit a coupling surface, that form a coupling gap (104) with a gap width decreasing in a radial direction, wherein a coupling element (102) can be brought into a first and a second position that differ with respect to the radial position inside the coupling gap (104) and therefore with respect to the contact pressure between the coupling element (102) and the coupling surfaces.
2. Combustion engine according to claim 1, characterised in that the coupling device (100) is formed self-reinforcing.
3. Combustion engine according to claim 1 or 2, characterised in that the coupling device (102) is elastically chargeable.
4. Combustion engine according to any one of claims 1 to 3, characterised in that the coupling element (102) engages the first position in the elastic non-applied state or as a result of a constructive elastic application, whereas the second position is adjustable by means of an active adjustment device.
5. Combustion engine according to claim 4, characterised in that the adjustment device exhibits an adjustable stop element (110) for the coupling element(102), that can be activated and deactivated, wherein in the activated state, it forms a stop for the coupling element (102) and in the deactivated state, no stop for the coupling element (102) forms.
6. Combustion engine according to claim 5, characterised in that a locking element (56) of the locking device (52) is also used as the stopping element (110) of the coupling device (100).
7. Combustion engine according to one of the preceding claims, characterised in that a locking element (56) of the locking device (52) is moveable in a locking recess (70) of the connecting rod (22) or the eccentric sleeve (40), wherein the locking recess (70) in relation to the locus of the locking element (56), on which this circulates relative to the component forming the locking recess (70) with a relative rotation between the eccentric sleeve (40) and the connecting rod (22), exhibits a larger dimension than the part of the locking element (56) provided for engaging into the locking recess (70).
8. Combustion engine according to claim 7, characterised by a return locking element (112) that can engage into the locking recess (70) together with the locking element (56).
9. Combustion engine according to claim 8, characterised in that the return locking element (112) is formed inclined in such a way that this is moveable from the locking recess (70) as a result of a contact with the edge of the locking recess (70).
10. Combustion engine according to claim 4 or one of the claims dependent on claim 4, characterised by at least two coupling devices (100), wherein the second position of the coupling element (102) of the first of the coupling devices (100) is adjustable by means of the adjusting device in a first rotational alignment of the eccentric sleeve (40) relative to the connecting rod (22) and the second position of the coupling element (102) of a second of the coupling devices (100) is adjustable by means of the adjustment device in a second rotational alignment of the eccentric sleeve (40) relative to the connecting rod (22) .
11. Combustion engine according to claim 10, characterised in that a first locking element (56) of the locking device (52), by means of which the eccentric sleeve (40) is lockable in a first rotational alignment relative to the connecting rod (22), and a second locking element (56) of the locking device (52), by means of which the eccentric sleeve (40) in a second rotational alignment relative to the connecting rod (22) is lockable, can be operated alternately by means of a combined operating element (64).
12. Combustion engine according to claim 11, characterised in that the operating element (64) can be swivelled about a swivel bolt that is part of a screw joint (78), with which the two parts forming the connecting rod end (26) are connected to the connecting rod (22).
13. Combustion engine according to claim 11 or 12, characterised in that the operating device (64) may also be used as a stop element (110) of the coupling devices (100).
14. Combustion engine according to any one of claims 11 to 13, characterised in that the operating element (64) can be secured in position in at least two operating end positions by means of a rest securing device (80).
15. Combustion engine according to any one of claims 11 to 14, characterised in that the operating element (64) is operable by means of an operating track (90) that is fastened to this such that it can be swivelled on a housing of the combustion engine.
16. Combustion engine according to claim 15, characterised in that the operating track (90) forms a guidance groove (94) running curved on both sides for the operating element (64).
17. Combustion engine according to claim 14 and claim 15 or 16, characterised in that the rest securing device (80) is formed in such a way that the operating element (64) does not come into contact with the operating track (90) in the operating end positions.
18. Combustion engine according to any one of claims 10 to 17, characterised in that

    - in the first rotational alignment of the eccentric sleeve (40) relative to the connecting rod (22), in which the second position of the coupling element (102) of the first coupling device (100) is set by means of the adjustment device, the second position of the coupling element (102) of the second coupling device (100) is set by means of a passive adjustment element (110) and

    - in the second rotational alignment of the eccentric sleeve (40) relative to the connecting rod (22), in which the second position of the coupling element (102) of the second coupling device (100) is set by means of the adjustment device, the second position of the coupling element (102) of the first coupling device (100) is set by means of a passive adjustment element (110).
19. Combustion engine according to claim 11 or any one of the claims dependent on claim 11, characterised in that

    - in one of the rotational alignments of the eccentric sleeve (40) relative to the connecting rod (22) the second locking element (56) by means of the operating element (64) is held in a release position, whereas the first locking element (56) is applied into a locking position by means of a spring element (62) supported between the locking elements (56) and

    - in another rotational alignment of the eccentric sleeve (40) relative to the connecting rod (22) the second locking element (56) is held in a release position by means of the operating element (64), whereas the second locking element (56) is applied into a locking position by means of the spring element (62).

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