EP3387235A1

EP3387235A1 - Internal combustion engine

Info

Publication number: EP3387235A1
Application number: EP16819016.3A
Authority: EP
Inventors: Volker Cornelius
Original assignee: Volkswagen AG
Current assignee: Volkswagen AG
Priority date: 2015-12-10
Filing date: 2016-12-08
Publication date: 2018-10-17
Also published as: WO2017097936A1; DE102015224907A1

Abstract

The invention relates to an internal combustion engine comprising a cylinder (12), a piston (18) that is movably located within the cylinder (12), a crankshaft (14) and a connecting rod (22) that connects the piston (18) to a crank pin (30) of the crankshaft (14). Rotatably mounted within the connecting rod top end (26) of the connecting rod (22) is an eccentric sleeve (40), which rotatably holds the crank pin (30) and which, when necessary, can be locked in relation to the connecting rod (22) in at least two rotational orientations by means of a locking device (52). To achieve this, a locking element (56) of the locking device (52) can be moved into a locking hollow (70) of the connecting rod (22) or of the eccentric sleeve (40). According to the invention, the locking hollow (70) has greater dimensions, with respect to the circular path of the locking element (56) followed by said locking element relative to the component forming the locking hollow during a relative rotation of the eccentric sleeve (40) and the connecting rod (22), than those of the part of the locking element (56) designed to engage in the locking hollow (70). A relatively large locking hollow (70) of this type guarantees a secure engagement of the locking element (56), even at high relative angular speeds of the locking element (56) and the component forming the locking hollow (70), since the locking element (56) is not merely able to move in the locking hollow (70) in one definite rotational direction defined by an angle between the eccentric sleeve (40) and the connecting rod (22), but can be moved through a greater angular range, so that sufficient time is available for moving the locking element (56) into the locking hollow (70), even when there are relatively large differences in the angular speeds.

Description

description

Internal combustion engine

The invention relates to an internal combustion engine having a cylinder, a piston movably guided within the cylinder, a crankshaft and connecting the piston with a crank pin of the crankshaft connecting rod, wherein a crank pin rotatably receiving eccentric sleeve is rotatably mounted within a connecting rod of the connecting rod, in at least two Drehausrichtungen relative to the connecting rod by means of a locking device can be blocked, for which purpose a blocking element of the locking device in a locking recess of the connecting rod or the eccentric sleeve is movable.

Such an internal combustion engine allows operation with a variable

Compression ratio, which sets as a result of a function of the Dre92 alignment of the eccentric sleeve resulting variable distance between the crank pin and the piston. 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 known for example from DE 197 03 948 C1. Locking the eccentric sleeve in one of the Drehausrichtungen is achieved in this internal combustion engine by means of a in a through hole of the connecting rod along a movement axis, which is parallel to the axes of rotation of the eccentric sleeve, guided and acted upon by a spring element locking pin in one of two by 180 ° with respect the rotational axes of the eccentric sleeve engages staggered locking openings engages. For this purpose, the locking openings are integrated into two annular disk-shaped edge sections of the eccentric sleeve that project beyond the opening formed by the large connecting rod eye.

Such an embodiment of a generic internal combustion engine requires an opening cross-section of the locking openings, which essentially corresponds to the cross section of the locking pin, for locking the eccentric sleeve in the intended rotational alignment with respect to the connecting rod as far as possible without play. However, this can lead to the problem that a secure engagement of the locking pin in the respective locking opening when reaching one of the Drehausrichtungen is not guaranteed if the differential angular velocity between the eccentric sleeve and the connecting rod is relatively high, because then, for reasons of inertia, the locking pin can not be accelerated sufficiently fast by means of the spring load and thus can be moved into the corresponding locking opening.

DE 197 03 948 C1 discloses that a device can be provided which brakes a relative rotation between the eccentric sleeve and the connecting rod in the areas in which the engagement between the locking pin and one of the locking openings. It can be assumed that the described problem is avoided by means of this braking device and, as a result of the reduced differential angular velocity, a secure engagement of the heavy bolt in one of the locking openings is to be ensured. A disadvantage of such a braking device is the associated relatively large design effort.

A generic internal combustion engine is furthermore known from EP 0 438 121 B1.

Based on this prior art, the present invention seeks to provide a way in a generic internal combustion engine a safe

Engagement of the locking element in the locking recess, even at relatively high

Differential angular velocities between the eccentric sleeve and the connecting rod to

guarantee.

This object is achieved by means of an internal combustion engine according to the patent claim 1. Advantageous embodiments of the internal combustion engine according to the invention are objects of the other claims and will become apparent from the following description of the invention.

To solve the problem is in an internal combustion engine comprising at least one cylinder, a piston movably guided within the cylinder, a crankshaft and connecting the piston with a crank pin of the crankshaft connecting rod, within a connecting rod of the connecting rod a crank pin rotatably receiving eccentric sleeve in turn is rotatably mounted, which in at least two Drehausrichtungen with respect to the connecting rod by means of a locking device (as required) can be locked, including a blocking element of the locking device in a locking recess of the connecting rod or the eccentric sleeve is movable, according to the invention provided that the locking recess with respect to an orbit of the locking element, on this rotates relative to the locking recess forming component in a relative rotation between the eccentric sleeve and the connecting rod, a (preferably at least 50%, more preferably at least 100%) has a larger dimension than the part of the blocking element intended for engagement in the blocking recess.

Such relative to the orbit of the locking element relatively large locking recess can ensure a secure engagement of the locking element even at large differential angular velocities between the locking element and the blocking recess forming component, because the blocking element not only in a concrete, defined by an angular value

Drehausrichtung between the eccentric sleeve and the connecting rod can be moved into the locking recess, but this is possible over a larger angular range, so that even at relatively high differential angular velocities, the time that is available to move the blocking element in the locking recess, is sufficient.

The term "blocking recess" is intended to encompass passage openings into which the blocking element or at least a part thereof can engage to form a form-locking lock.

To a mobility between the blocking 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) in engaging in the locking recess

Preferably, to avoid or limit the blocking element despite such a relatively large locking recess, preferably a return blocking element may further be provided, which can engage with the blocking element in the locking recess and thereby a portion of the locking recess, in which the locking element after the intervention in the

Barrier recess is not arranged, can fill out. It can also be provided that the locking element and the return locking element, if both engage in the locking recess, not fill the locking recess completely, because between these a distance is formed. The blocking element then prevents a relative rotation of the eccentric sleeve to the connecting rod in one of the directions of rotation by abutment at one end (with respect to the extension along the orbit) of the locking recess and the backstop a relative rotation in the other direction of rotation by a stop on the

corresponding other end of the Sperrvertiefung.

In order to achieve an automatic function of the Rücklaufsperrelements can be provided that this particular beveled on the blocking element facing side is formed such that this due to a contact (due to rotation of the eccentric sleeve relative to the connecting rod) with the edge of the locking recess from the locking recess is moved out, this moving out further preferably leads to an (increasing) bias of a spring element. This bias of the

Spring element can then ensure a re-engagement of the return locking element in the / a locking recess, if this is again or another locking recess positioned as a result of rotation of the eccentric sleeve corresponding to the backstop element.

In a preferred embodiment of the internal combustion engine according to the invention can be provided that a first locking element of the locking device, by means of which the eccentric sleeve in a first Dregehrichtung with respect to the connecting rod is lockable, and a second locking element of the locking device, by means of which the eccentric sleeve in a second Drehausrichtung with respect to the connecting rod is lockable, are provided.

In such an embodiment of the internal combustion engine according to the invention can then also be provided that the first locking element and the second locking element by means of a common actuating element are actuated alternately. The

Actuator can preferably be designed such that it is pivotable about a pivot pin, which is part of a screw, with the two connecting rod eye forming parts of the connecting rod are connected. The actuator would then be part of the connecting rod and would be moved during operation of the internal combustion engine with this. By using a screw, with a two-piece in a known manner connecting rod eye is held together, as a rotary bearing element for the actuating element, a

Additional mass, resulting from the integration of the actuator in the connecting rod, are kept low.

In particular, to achieve the most secure blocking of the eccentric sleeve in one of the Drehausrichtungen relative to the connecting rod can be provided that the actuating element in two preferably actuating end positions (in which the actuating element is positioned when one of the locking element engages in the associated locking recess) by means of a latching fuse position secure is. This safety catch is preferably designed such that it by an active action with the aim of switching the

Actuator is solvable by only a force, but this forces are required, which in a normal operation of the internal combustion engine is not in the

corresponding direction act on the actuator. An actuation of the actuating element can preferably be effected by means of an actuating rail. In this case, a "guide rail" is understood to mean a guide element which is positioned in such a way that the actuating element is moved at least in sections along the crankshaft during each revolution, this being used to actuate the crankshaft

Actuator is movable from a first position to a second position. After such movement of the operating rail performs a subsequent

Moving the operating member to a contact with a guide surface of the operating rail, whereby the actuating element is displaced or pivoted and thereby switched. The operating rail can for this purpose preferably on a

Housing of the internal combustion engine to be fixed or not moved at least as a result of a different type of attachment with the crankshaft or the connecting rod, so that there is no increase of moving masses for the operation of the internal combustion engine by the operating rail. Particularly preferably it can be provided that the operating rail is pivotally attached to a particular housing of the internal combustion engine, because characterized compared to a likewise possible embodiment with a slidably attached to particular the housing operating rail a simplified operation by means of one of the operating rail associated (for example, hydraulic,

pneumatic, electromotive or electromagnetic) actuator can be enabled.

For a possible shock-free operation of the actuating element by the actuating rail may preferably be provided that the actuating rail forms a both sides arcuately tapered (i.e., narrowing) guide groove for the actuating element. In this case, the arcuate shape may preferably be formed such that the direction of movement of the actuating element, as long as it is moved by the guide, is aligned as tangent as possible.

Further preferably, it may be provided that the safety catch, which is preferably provided in the case of the internal combustion engine according to the invention, is designed for the actuating element such that the actuating element does not contact the actuating rail in the actuating end positions. Friction losses due to cyclical grinding of the actuator along the guide rail when the actuator in one of its

Operating end positions is located (which can always be the case when no switching of the compression of the internal combustion engine takes place, and thus during most of the operating time of the internal combustion engine), can be avoided, which is not only can positively affect the wear of the actuator and the operating rail but also on the acoustic behavior of the internal combustion engine.

In a preferred embodiment of an internal combustion engine according to the invention with (at least) two blocking elements, which can be actuated alternately by a common actuating element, it can also be provided that

- In one of the Drehausrichtungen the eccentric sleeve relative to the connecting rod the second

Locking element is held by means of the actuating element in a release position, while the first locking element by means of a supported between the locking elements

Spring element is acted upon in a (the eccentric sleeve in one of the Drehausrichtungen blocking) locking position and

- In one / the other Drehausrichtung the eccentric sleeve relative to the connecting rod, the first locking element is held by means of the actuating element in a release position, while the second locking element is acted upon by the spring element in a locking position.

This allows a structurally advantageous embodiment for the operation of both locking elements provided actuator can be achieved.

In a preferred embodiment of an internal combustion engine according to the invention may still be provided a coupling device by means of which the eccentric sleeve is temporarily coupled to the crankshaft to rotate the eccentric sleeve relative to the connecting rod. Thereby, a rotation of the crankshaft or the crank pin relative to the connecting rod in the operation of the internal combustion engine can be exploited to the

Temporarily take eccentric sleeve and thereby rotate quickly and safely from one to the other Drehausrichtung. This is preferably always done when the eccentric sleeve is not locked in one of the Drehausrichtungen by means of the locking device. Since such an actively effected twisting of the eccentric sleeve relative to the connecting rod, in particular at relatively high rotational speeds of the crankshaft to correspondingly high

Difference angular velocities between the eccentric sleeve and then leads to this relatively rotating connecting rod, the inventively achieved by the relatively large configuration of the locking recess compared to the blocking element advantage can have a particularly positive effect.

The coupling device may preferably be designed to be non-positively acting (particularly preferably exclusively). This can in particular simplify the structural design of the coupling device and a sudden take away the Eccentric sleeve through the crankshaft, as could be the case with a likewise conceivable positive-acting coupling device, can be avoided. This aspect can, in particular because of in an operation of an inventive

Internal combustion engines occurring large differential angular velocities between the in one of the Drehausrichtungen still rotatably relative to the connecting rod arranged eccentric sleeve and the crankshaft, by which the eccentric sleeve is to be taken afterwards, be relevant ..

The indefinite articles ("one", "one", "one" and "one"), in particular in the

Claims and in the claims generally explaining the description are to be understood as such and not as numerical words. Correspondingly thus concretized

Components are thus to be understood that they are present at least once and may be present more than once.

The present invention will be explained in more detail with reference to embodiments shown in the drawings. In the drawings shows:

1 shows 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 isolation, the for a change in the compression of

Internal combustion engine relevant components in a perspective view;

FIG. 3 shows the components according to FIG. 2 in a further perspective view; FIG.

Fig. 4: the components according to FIGS. 2 and 3 (but without operating rail of

Internal combustion engine) in a further perspective view;

FIG. 5 shows the components according to FIG. 4 in a further perspective view; FIG.

6 shows the components according to FIGS. 4 and 5 in a further perspective view;

7 shows in a detail a view from below of the components according to FIGS. 4 to 6 with an actuating element of the internal combustion engine in a first position; 8 shows a radial section through a section of a crankshaft, a connecting rod, an eccentric sleeve, an adjusting and a locking device and two

Clutch devices of the internal combustion engine, wherein a first locking element of the locking device in a locking position and a second locking element of

Locking device is in a release position;

9 shows a view according to FIG. 7 with the actuating element in a second position;

10 shows a view according to FIG. 8, but with the first blocking element now in a release position and the second blocking element in an intermediate position; FIG.

Fig. 1 1: a view according to FIG 10, but now with the second locking element is in a locked position.

FIG. 12 shows a cross section through the components according to FIGS. 7 to 11; FIG.

Fig. 13: in isolated representation, the actuating element of the internal combustion engine in one

perspective view;

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

FIG. 15 shows the crank mechanism of the internal combustion engine according to FIG. 14 in a side view; FIG.

FIG. 16 shows the detail marked XVI in FIG. 15 in enlarged and partially cutaway view; FIG.

Fig. 17: in isolation, the for a change in the compression ratio

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

FIG. 18 shows the components according to FIG. 17 in a further perspective view. FIG.

1 to 13 show an internal combustion engine according to the invention, which is designed for example as a gasoline or diesel engine, in a first embodiment. This includes, according to FIG. 1, a cylinder crankcase 10, within which one or more cylinders 12 are formed. At the upper end of the cylinder crankcase 10 in FIG. 1, an unillustrated cylinder head connects to it, while the lower end of the

Cylinder crankcase 10 is provided for connection to an oil pan, also not shown. A crankshaft 14 of the internal combustion engine receiving

Crankshaft space 16 would then be formed substantially fully closed.

Within the (or each) cylinder 12, a piston 18 is movably mounted axially (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, defines with the cylinder head a combustion chamber in which a fuel / fresh gas mixture is burned during a working cycle during operation of the internal combustion engine in order to perform work. A pressure increase 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 rotational 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 forms a first, so-called small connecting rod eye 38 (see Fig. 15) which rotatably receives a piston pin 24 of the piston 18. Furthermore, the lower end of the connecting rod 22 with a there also formed, so-called large connecting rod eye 26 (see.

2) are 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 compressive 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.

As is apparent in particular from FIG. 15, 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) with one another and, on the other hand, at least partially serve the rotatable mounting of the crankshaft 14 within the cylinder crankcase 10. The rotatably mounted within the large connecting rods 26 of the connecting rod 22 crank pin 30 are bounded on both sides by disk-shaped portions of the crankshaft, which form the so-called crank webs 34 which connect the crank pin 30 with the bearing portions 32, and the other the crank webs 34 with respect to the Form rotational axis 28 radially opposite balancing masses 36, whereby free mass forces and

Mass moments during the rotation of the crankshaft 14 should be avoided as possible. In order to change the compression ratio in the operation of the internal combustion engine, ie the ratio of the volume of the combustion chamber in the bottom dead center of the piston 18 to the volume at top dead center of the piston 18, in two stages, is provided, the / the crank pin 30 with interposition (respectively ) an eccentric sleeve 40 within the / the large Pleuelauges / connecting rod 26 to store. The (each) eccentric sleeve 40 comprises a tubular support portion 42, the cylindrical inner surface of which serves as a sliding surface for the rotational support of the crankpin 30 received therein and the cylindrical surface thereof

Outer surface serves as a sliding surface for the rotary bearing of the eccentric sleeve 40 within the large connecting rod 26 of the associated connecting rod 22. The inner and the outer surface of the bearing portion 42 are not coaxial but radially offset by a defined distance from each other, whereby the distance between the pivot or rotation axis 44 of the small connecting rod to 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 in response to the Drehausrichtung the eccentric sleeve 40 within the large connecting rod 26 changes.

At the two longitudinal axial ends of the tubular bearing portion 42 of the

Eccentric sleeve 40 in each case a limiting portion 48 via which is each formed by an annular disc which extends radially outwardly from the bearing portion 42 and thereby a mobility of the eccentric sleeve 40 within the large connecting rod 26 in the axial direction with respect to the longitudinal axis 50 of the large connecting rod eye 26 limited.

By means of a locking device 52, the rotatability of the eccentric sleeve 40 can be blocked within the large connecting rod eye 26 of the connecting rod 22 in two defined Drehausrichtungen, wherein provided in the present embodiment, the two Drehausrichtungen the smallest and the largest distance between the piston 18 and the associated crank pin 30 correspond.

As can be seen in particular from FIGS. 8 to 11, the blocking device 52 comprises two mutually coaxially aligned blocking elements 56 which are displaceably arranged within a cylindrical receiving opening 54 of the connecting rod 22. The receiving opening 54 is at the outermost end (forming the large connecting-rod eye 26). End of the connecting rod 22 and thus positioned in extension of a connecting rod shaft 58 of the connecting rod 22. In particular, it may 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 biased spring element 62 is arranged in the form of a cylindrical coil spring, the 56 and the two locking elements away from each other in the direction of the associated end of the receiving opening 54 and in the direction of the adjoining boundary portion 48 of the eccentric sleeve 40th

applied.

The axial mobility of the locking elements 56 within the receiving opening 54 is variably limited in dependence on the position of an actuating element 64. For this purpose, in each case a driving projection 66 of the actuating element 64 shown in isolation in FIG. 13 engages in a (with respect to the longitudinal axis of the receiving opening 54 or the

Movement axis of the locking elements 56) circumferential driving groove 68 of the locking elements 56, whereby on the one hand a mobility of the locking elements 56 within the

Receiving opening 54 limited and this on the other for a change of the

Compression ratio in which the internal combustion engine can be operated, can be moved by switching the operating member 64 between two actuation end positions within the receiving opening 54.

FIGS. 7 and 8 show the actuating element 64 in a first embodiment

Actual end position, in addition, a first of the locking elements 56, which is shown in Figs. 8, 10 and 1 1 right, in a through hole (corresponding to the embodiment of FIGS. 7 to 1 1) or edge-side recess (corresponding to the embodiment 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 Drehausrichtung with respect to the connecting rod 22 and the large connecting rod 26. On the other hand, FIGS. 9 and 11 show the actuating element 64 in the second actuation end position, in which the second of the locking elements 56, which is shown on the left in FIGS. 8, 10 and 11, fits into a corresponding limiting section 48 of the eccentric sleeve 40 trained locking recess 70 can engage when the eccentric sleeve 40 is in the associated Drehausrichtung, which is offset with respect to the first Drehausrichtung the eccentric sleeve 40 (as shown in FIGS. 8 and 10) by approximately 180 °. In these two Drehausrichtungen the eccentric sleeve 40, which are lockable by means of the locking device 52, the distances between the piston 18 and the associated differ

Crankpin 30 due to the eccentric design of the eccentric sleeve 40th This

different distances are also apparent from a comparison of Figs. 8 and 1 1, from which the different wall thicknesses of the tubular bearing portion 42 of the eccentric sleeve 40 in the portion between the crank pin 30 and the Locking device 52 receiving portion of the connecting rod 22 can be seen. In the

Drehhausrichtung according to FIG. 8, the wall thickness of the corresponding portion of the bearing portion 42 of the eccentric sleeve 40 is greater than in the Drehausrichtung according to FIG. 1 1, whereby the distance between the crank pin 30 and the piston 22 in the

Drehausrichtung according to FIG. 8 is smaller than that in the Drehausrichtung according to FIG. 1 1.

Fig. 10 shows the positions of the locking elements 56 after switching the

Actuator 64 of the u.a. in Fig. 7 illustrated first Betätigungsendstellung in the u.a. in Fig. 9 illustrated second Betätigungsendstellung, but even before the eccentric sleeve 40 has been rotated from the Drehausrichtung according to FIG. 8 in the Drehausrichtung according to FIG. 1 1. In Fig. 10 it is shown that the first blocking element 56 shown on the right is in a release position in which this out of engagement with the

associated locking recess 70 of the eccentric sleeve 40 and also in a defined distance with respect to the associated boundary portion 48 of the eccentric sleeve 40 is arranged. Moving the first blocking element 56, shown on the right, starting from the blocking position according to FIG. 8 into the release position according to FIG. 10, is achieved by switching over the actuating element 64 from a first actuating end position according to FIG. 7 to the second actuating end position according to FIG 9 reaches, wherein this is pivoted about a pivot axis 72. It takes the appropriate

Mitnahmevorsprung 66 of the actuating element 64 as a result of contact with the inner boundary wall of the driving groove 68 with the first blocking element 56 and shifts this 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 opportunity to move further in the direction of the corresponding end of the receiving opening 64, this movement being supported by the bias of the locking elements 56 supported by the movement of the first locking element 56 in the direction of the longitudinal axial Center of the receiving opening 64 further biased spring element 62 is effected. As long as the eccentric sleeve 40 is not yet in the illustrated in Fig. 1 1 second

Dredrehrichtung has been rotated, this mobility of the second locking member 56 is limited due to contact with the inside of the associated limiting portion 48 of the eccentric sleeve 40. Only shortly before reaching the second Drehrerichtung the second locking element 56 can engage in the then correspondingly associated associated locking recess 70 and thus moved into its blocking position shown in FIG. 1 1. In a renewed switching of the actuating element 64, then from the second actuation end position shown, inter alia, in FIG. 9 into the first shown, inter alia, in FIG

Betätigungsendstellung, is in accordance with reverse order, the second

Locking element 56 moves into the associated release position 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 has been rotated again by about 180 ° within the large connecting rod eye 26.

The connecting rod 22 comprises two parts screwed together, one the small connecting rod 38, the connecting rod shaft 58 and a half of the large connecting rod eye 26 forming

Pleuelgrundkörper 74 and a second half of the large connecting rod 26 forming and the locking device 52 integrating connecting rod 76. This bipartite of the connecting rod 22 in the region of the large connecting rod 26 allows the connection of the connecting rod 22 with the corresponding bearing pin 30 of the one-piece crankshaft 14 during assembly the internal combustion engine. The parting plane between the Pleuelgrundkörper 74 and the

Connecting rod cover 76 is perpendicular to the longitudinal axis 60 of the connecting rod 22nd

(or the connecting rod shaft 58). Furthermore, the axis of rotation 50 of the eccentric sleeve 40 extends within the large connecting rod 26 within this parting plane, resulting in a radial orientation of this parting plane with respect to the large connecting rod 26. As can be seen in particular in FIG. 12, the screw of one of the screw connections 78 between the connecting rod main 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 actuator 64 is pivotable to be moved back and forth between the two Betätigungsendstellungen, thus corresponds to the longitudinal axis of the screw of this screw 78th

A backup of the actuating element 64 in its two Betätigungsendstellungen by means of a latching fuse 80, which, according to FIGS. 12 and 13 of one of a

Spring element 82 loaded in a guide opening of the connecting rod 22 and the connecting rod cover 76 movably guided detent ball 84 in conjunction with one of two juxtaposed, cup-shaped detent recesses 86 which are integrated into the adjacent portion of the actuating element 64 is formed. When switching the actuating element 64 between its Betätigungsendstellungen each locking ball 84 must be raised under further bias of the associated spring element 82 to overcome the arranged between the two locking recesses 86 web 88. For this purpose, a switching moment (about the pivot axis 72 of the actuating element 64) is required, which is not caused by forces normally occurring during operation of the internal combustion engine becomes. An unwanted, automatic switching of the actuating element 64 can thus be avoided by the safety catch 80. On the other hand, only the application of a corresponding switching torque to the actuating element 64 is required for switching, without a positively acting lock would have to be solved.

An actuation of the actuating element 64 by means of a pivotable on the

Cylinder crankcase 10 attached actuating rail 90, as shown in FIGS. 1 to 3. In this case, the actuating rail 90 in Fig. 1 in the manner of a

Exploded view spaced from the junction on the cylinder crankcase 10 and thus shown by its actual operating position within the crankshaft space 16. In its actual functional position (see Figures 2 and 3), the actuating rail 90 is located so close to the axis of rotation 28 of the crankshaft 14, that the actuating element 64 connected to the connecting rod 22 with one of them

Guide member 92 is disposed in the position corresponding to the bottom dead center of the piston 18 and at least over a defined angular range before reaching this position within a formed of two side walls of the operating rail guide groove 94. The width of the guide groove 94 assumes thereby starting from an inlet, i. the end at which the guide member 92 of the actuating element 64 enters the guide groove 94 in the context of each revolution of the crankshaft 14, continuously from. In addition, the longitudinal extension of the actuating rail 90 to the orbit of the

Guide element 92 of the actuating element 64, which describes this due to a rotation of the crankshaft 14, adapted by means of a curved course, so that

In particular, it may be provided that a distance that the underside of the

Guide element 92 to the groove bottom 96 of the guide groove 94 of the actuating rail 90 complies, remains substantially the same over the course of the movement of the guide member 92 within the guide groove 94. It is preferably provided that the

Guide member 92 of the actuator 64, the groove bottom 96 of the guide 94 contacted 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 will be in contact with one of the inside walls formed by the side walls of the actuating rail 90 during each revolution of the crankshaft 14

Guiding surfaces 98 of the guide groove 94 of the actuating rail 90 guided by the guide groove 94 therethrough. In particular, it can be provided that the guide element 92 at least at the end of the guide groove 94 substantially exactly centered between the two Sidewalls is guided. If, however, starting from such a starting position, the actuating rail 90 is pivoted by means of a not shown, driven by a likewise not shown engine control of the engine actuator in the corresponding other functional position, the guide member 92 of the contacted

Actuator 64 the next entering the guide groove 94 through the

Actuate the actuating rail 90 in the orbit of the guide member 92 gerrückte guide surface 98 so that the guide member 92 along this guide surface 98 guided while the actuator 64 is moved or pivoted due to the narrowing guide groove 94 in the direction of its other Betätigungsendstellung. In this case, caused by the contact with the corresponding guide surface 98

Pivoting movement of the actuating element 64 is only so great that the detent ball 84 of the safety catch 80 is moved over the web 88 formed between the two detent recesses 86. The last, relatively small section of the pivoting movement of the

Actuator 64 in its then intended Betätigungsendstellung is achieved by the engagement of the detent ball 84 in the corresponding detent recess 88. As a result, it can be effected that the guide element 92 of the actuating element 64 is still far away from the guide surface 98 of the actuating rail 90 effecting the switchover and thus there is no contact with this or both sidewalls of the actuating rail 90 in the subsequent operation of the internal combustion engine.

The guide surfaces 98 of the operating rail 920 are formed curved such that the guide member 92 of the actuating element 64 after switching the

Actuating rail 90 runs in the tangential direction on the corresponding guide surface 98, whereby a switching of the actuating element 64 can be achieved with a uniformly increasing as possible force curve. This can have an advantageous effect on the life of the components involved and on the acoustic behavior of the internal combustion engine.

To allow a safe and fast rotation of the eccentric sleeve 40 between the two lockable by the locking device 52 Drehausrichtungen after the

Actuator 64 by means of the actuating rail 90 of one of

Operating end positions has been pivoted into the other of the actuating end positions, the internal combustion engine according to the invention comprises two non-positively acting

Coupling devices 100, by means of which the eccentric sleeve 40 is temporarily coupled to the crankshaft 14 in order to rotate the eccentric sleeve 40 relative to the connecting rod 22 and the large connecting rod eye 26. Each of the coupling devices 100 includes a sickle-shaped or partially annular coupling element 102, which on the

Outside each one of the boundary portions 48 of the eccentric sleeve 40 and thus arranged in a formed between the eccentric sleeve 40 and the adjacent crank arm 34 of the crankshaft 14 coupling gap 104. It is an end of the

Coupling member 102 rotatably in the associated limiting portion 48 of

Eccentric sleeve 40 is fixed and the coupling element extends, starting from this pivot bearing in the direction of rotation 106 of the eccentric sleeve, these in the operation of the

Internal combustion engine (and in a blocking in one of the Drehausrichtungen) relative to the associated crank webs has (see Fig. 2 and 3).

As can be seen for example from FIGS. 8, 10 and 11, the gap width of the

Coupling gap 104 in the radial direction to the outside, which by a corresponding inclination of serving as a clutch surfaces (the eccentric sleeve 40 facing) inner sides of the crank webs 34 by an angle of approximately 3 ° relative to an orientation perpendicular to the axis of rotation 50 of the eccentric sleeve 40th is achieved within the large Pleuelauges 26 or the rotation axis 46 of the crank pin 30 within the eccentric sleeve 40. The cross section of each of the coupling elements 102 is correspondingly tapered or wedge-shaped, so that a parallel alignment of the

Coupling surfaces of the coupling elements 102 to the coupling surfaces formed by the crank cheeks 34 results. The coupling elements 102 of both coupling devices 100 are each acted upon by a prestressed spring element 108 in the direction radially outward and thus in the narrowing coupling gap 104 inside. These

Spring loading results in output loads for the coupling devices 100, through which the coupling surfaces of the coupling elements 102 to the coupling surfaces of the crank webs 34 and the eccentric sleeve 40 (from the outside of the

Limiting portions 48 of the eccentric sleeve 40 are formed) are pressed. The output loads thus generated lead to frictional forces, which are opposite to a relative movement between the eccentric sleeve 40 and the crank webs 34 and their direction of action is such that they additionally a moment about the respective pivot bearing of the coupling elements 102 in the direction of further pivoting outwards and thus an additional Pulling into the respective narrowing coupling gap 104 effect. Thereby, a self-reinforcement of the non-positive effects of

Clutch devices 100 achieved in the respective closed state.

During operation of the internal combustion engine and a blocking of the eccentric sleeve 40 in one of the Drehausrichtungen the coupling devices 100 are opened by the Coupling elements 102 are pivoted by a respective contact with a stop element 1 10 so far under further bias of the respective spring element 108 in that the least possible adhesion between at least the coupling surfaces of the crank webs 34 and the adjacent coupling surfaces of the coupling elements 102 is given. In each case, that coupling element 102, which is on the one

Limiting portion 48 of the eccentric sleeve 40 is rotatably mounted in the result of the corresponding selected Betätigungsendstellung of the actuating element 64 the

associated locking element 56 engages in the locking recess 70, is deflected by means of an associated stop element 1 10 of the actuating element 64 inwardly, while a deflection of the respective other coupling element 102 by means of a passive, immovable stop element 1 10 takes place.

Now, if the actuator 64 is switched, the previously held by this held held coupling element 102 is released so that this pivots due to the spring load to the outside and thus in the associated narrowing coupling gap 104, whereby at least the corresponding coupling device 100 is closed. This closed coupling device 100 causes then initially alone co-rotation of the eccentric sleeve 40 with the relative to the large connecting rod 26 rotating crank arms 34. This co-rotation causes a release of the other coupling element 102 of the

deflecting contact with the passive stop element 1 10, so that then also pressed this other coupling element 102 due to the spring load in the narrowing coupling gap 104 and thus this coupling device 100 is closed. For the rest of the rotation of the eccentric sleeve by 180 ° to the other Drehausrichtung then cause both coupling devices 100, the positive coupling of

Eccentric sleeve 40 to the associated crank webs 34 of the crankshaft 14. Shortly before reaching the new Drehausrichtung the eccentric sleeve 40 then engages the other

Locking element 56, as already described with reference to Figures 10 and 1 1, in the locking recess 70 of the associated boundary portion 48 of the eccentric sleeve 40 and the

Coupling elements 102 of both coupling devices 100 then run on the

corresponding stop elements 1 10, on the one hand due to the switching of the

Actuator 64 disengaged second stop element 1 10 of the actuator 64 and on the other hand on the eccentric sleeve 40 on both sides superior passive stop element 1 10, which in turn under renewed bias of

Spring elements 108 pivoted inward and thus the coupling devices 100 are released. The internal combustion engine can then continue to be operated with a modified compression ratio, wherein the eccentric sleeve 40 in the new Drehausrichtung relative to the Connecting rod 22 is locked and due to the dissolved coupling devices 100 again largely friction-free relative to the crank webs 34 is rotatable.

Due to the high speeds with which internal combustion engines, which are provided for example for driving motor vehicles, operated, resulting in high

Differential angular velocities between the temporarily coupled by means of the coupling devices 100 with the crank cheeks 34 eccentric sleeve 40 and the locking device 52 integrating connecting rod 22. In spite of these high differential angular velocities a secure engagement of each spring-loaded during the change of Drehausrichtung against the inside of the associated Begrenzungsabschnitts 48 of the eccentric sleeve 40th To ensure pressed locking element 56, each of the locking recesses 70 with respect to an orbit of the associated locking element 56 (in relation to the connecting rod 22 rotating eccentric sleeve 40) has a larger dimension than that provided for engagement in the locking recess 70 part of the locking member 56. The locking recesses 70 are as

arcuate, elongated through holes or recesses formed. The blocking elements 56 can thus engage not only in a concrete Drehrerichtung 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 due to the spring load in the direction of

associated Sperrvertiefungen 70 are accelerated, with sufficient certainty.

The larger dimensions of the locking recesses 70 compared to those in this

engaging parts of the locking elements 56 leads despite a blocking by one of

Locking elements 56 in principle to a (limited) rotational mobility between the eccentric sleeve 40 and the large connecting rod eye 26. To eliminate this rotational mobility or at least reduce as much as possible each blocking element 56 is still attached to the connecting rod 22 and concretely the connecting rod cover 76, passive backlash element. 1 12, which, when the associated blocking element 56 at the respect to the

Direction of rotation 106 of the eccentric sleeve 40 engages relative to the crank webs 34 front end of the associated locking recess 70, in the region of the other end also engages in this locking recess 70 and thus together with the locking element 56, the eccentric sleeve 40 largely free of play with the connecting rod 22 connects. Moving out of engaging in a locking recess 70 backstop element 1 12, although the associated locking element 56 due to a switching of the actuating element 64 from the

associated blocking recess 70 has been moved out, is automatically achieved in that the return blocking elements 1 12 are formed in each case with an inclined surface, that this in a then entrained entrainment of the eccentric sleeve 40 by the crankshaft 14 in contact with the edge of the respective locking recess 70 among others

Preload a spring element 1 14 are deflected. For a structurally advantageous integration of the two return locking elements 1 12 in the connecting rod 22 is provided that these are each attached to a free end of a leg of the formed in the form of a U-shaped leaf spring spring element 1 14 and the spring element 1 14 in the region of its arcuate portion in which it is not deflected, is attached to the actuator 64.

As the connecting rod 22 in the region of the large connecting rod eye 26 and the eccentric sleeve 40 is formed of two parts or half shells, wherein the dividing plane 1 16 between these parts is preferably arranged such that the axis of rotation 46 of the

Crankpin 30 within the eccentric sleeve 40 or the axis of rotation 50 of

Eccentric sleeve 40 within the large Pleuelauges 26 within this parting plane 1 16 extends. For a possible advantageous installation of the eccentric sleeve 40 is further provided that bearing openings (and in particular the longitudinal axes thereof), which serve the pivotal mounting of the coupling elements 102 in the associated Begrenzungsabschnitten 48 of the eccentric sleeve 40, 16 are also arranged in this parting plane. The same applies to radially with respect to one of the axes of rotation 46, 50 of the eccentric sleeve aligned

Guide openings 1 18 for the deflectable ends of the arcuately guided on the inner sides of the associated coupling elements and in the region of the rotary bearings of the

A separate connection of the two parts of the eccentric sleeve 40 is not required because they are held together due to the arrangement within the large connecting rod eye 26.

The illustrated in FIGS. 14 to 17 second embodiment of an internal combustion engine according to the invention differs from the first embodiment shown in FIGS. 1 to 13 essentially only in terms of the design of the coupling devices 100 and actively releasable for releasing the coupling devices 100 Einsteilvorrichtung.

In this internal combustion engine, two positively acting coupling devices 100 are provided, each having a coupling element 102 which is resiliently acted upon in a closing the respective coupling device 100 and thus the eccentric sleeve 40 to a rotational movement of the crankshaft 14 coupling position. While in the embodiment according to FIGS. 1 to 13 coupling elements 102 are provided, which are acted upon by means of separate prestressed spring elements 108, the coupling elements 102 formed in the embodiment according to FIGS. 14 to 17 itself elastically deflectable. Specifically, these are each in the form of a spiral spring, one end of which engages in an opening in the associated limiting section 48 of the eccentric sleeve 40 and is secured in position, and extending from this end by more than 360 ° and concretely by about 450 ° formed by the eccentric sleeve 40 storage opening for the associated crank pin 30 of the crankshaft 14 is guided around. The second end of each of the helical spring-shaped coupling elements 102 is angled and supported with this angled portion edge on the associated boundary portion 48 of the eccentric sleeve 40 from. The geometry of the spiral spring-shaped coupling elements 102 is selected such that they are elastically widened at a concern with the angled ends at the edges of the limiting sections 48 and thus biased, which leads to an endeavor of the coupling elements 102 to curl narrower or to a smaller diameter , This leads to a constructive elastic loading of the coupling elements 102, because they thereby automatically pull into the coupling gaps 104 (see FIG 34 cause, unless they are radially expanded by a stop against stop elements 1 10 and thus the frictional connection between the coupling elements 102 and the coupling surfaces of the crank webs 34 and the eccentric sleeve 40 is repealed.

Another difference of the internal combustion engine according to FIGS. 14 to 18 to that according to FIGS. 1 to 13 is that the activatable and deactivatable

Stop elements 1 10, of which in each case one of the two Drehausrichtungen the

Eccentric sleeve 40, which are lockable by means of the locking device 52, one acts on one of the coupling elements 102, while at the same time the other coupling element 102 is radially expanded by contact with a passive stop element 1 10 (see Fig. 18), not by the actuating element 64th but are formed by the respective blocking element 56. For this purpose, it is provided that the corresponding blocking element 56, which also engages in the associated locking recess 70 of the eccentric sleeve 40, as far as the

Through hole in the corresponding limiting portion 48 of the eccentric sleeve 40 formed locking recess 70 protrudes into the associated coupling gap 104 that with closed coupling devices 100 and thus at a carry the eccentric sleeve 40 by the crankshaft 14 at the edge of the corresponding

Limiting portion 48 supported end of the corresponding coupling element 102 upon reaching the corresponding Drehausrichtung the eccentric sleeve 40 on the in the Coupling gap 104 protruding part of the corresponding locking element 56 runs and thereby this coupling element 102 is radially expanded (see Fig. 17). At the same time the corresponding end of the other coupling element 102 runs on the outside on the associated passive stop element 1 10 and is also widened. Both are

Coupling devices 100 open and a frictional connection between the coupling sleeve 102 positively connected to the eccentric sleeve 40 and the crank webs 34 of the crankshaft 14 is substantially interrupted.

If, starting from such a starting position in which the internal combustion engine is operated at a constant compression ratio, the actuating element 64 is switched over by means of the actuating rail 90 in accordance with the procedure in the internal combustion engine according to FIGS. 1 to 13, again the locking element 56 located in a locking position moved to a release position. The then by this blocking element 56 then no longer widened coupling element 102 then causes first alone a driving the eccentric sleeve 40 through the crankshaft 14, whereby in a first, relatively small portion of the rotation of the eccentric sleeve 40 relative to the large connecting rod eye 26 and the second coupling element 102 except Engagement with the passive stop element 1 10 is brought. This second coupling element 102 then also couples the eccentric sleeve 40 frictionally to the associated crank cheek 34 of the crankshaft 14. The second locking elements 56 engaging in the associated locking recess 70 upon reaching the other rotational orientation of the eccentric sleeve 40 then expands the associated coupling element 102 radially, while the other coupling element 102 is radially expanded by the associated passive stop element 1 10, so that in turn both

Clutch devices 100 are opened.

Cylinder crankcase

cylinder

crankshaft

crankshaft space

piston

Longitudinal axis of the cylinder / piston

pleuel

piston pin

big connecting rod eye

Rotation axis of the crankshaft

crank pin

Bearing section of the crankshaft

crank web

Compensation mass of the crankshaft

small connecting rod eye

eccentric

Storage section of the eccentric sleeve

Rotation axis of the small connecting rod eye

Rotation axis of the cylindrical inner surface of the eccentric sleeve

Limiting section of the eccentric sleeve

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

locking device

Receiving opening of the connecting rod

blocking element

connecting rod shaft

Longitudinal axis of the connecting rod

Spring element of the locking device

actuator

Carrying projection of the actuating element

Takeover of the barrier element

blocking recess

Pivot axis of the actuating element Pleuelgrundkörper

connecting rod

Screw connection between the Pleuelgrundkörper and the connecting rod cover

catch lock

Spring element of the safety catch

Detent ball of the safety catch

Detent recess of the safety catch

Bar of the safety catch

balance rail

Guide element of the actuating element

Guide groove of the operating rail

Groove bottom of the guide groove

Guide surface of the guide groove

coupling device

coupling member

coupling gap

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

Spring element of the coupling device

stop element

Return member

Spring element for the backstop element

Parting plane between the parts of the eccentric sleeve

Guide opening for the spring element of the coupling device

Claims

claims

1. Internal combustion engine with a cylinder (12), one within the cylinder (12)

movably guided piston (18), a crankshaft (14) and a piston (18) with a crank pin (30) of the crankshaft (14) connecting the connecting rod (22), wherein within a connecting rod (26) of the connecting rod (22) has a Rotatable crank pin (30)

receiving eccentric sleeve (40) is rotatably mounted in at least two

Drehhausrichtungen relative to the connecting rod (22) by means of a locking device (52) is lockable, including a locking element (56) of the locking device (52) in a locking recess (70) of the connecting rod (22) or the eccentric sleeve (40) is movable, characterized in that the blocking recess (70) is in relation to the orbit of the

Locking elements (56), on which this rotates relative to the locking recess (70) forming member in a relative rotation between the eccentric sleeve (40) and the connecting rod (22), a larger dimension than that for engagement in the locking recess (70) provided Part of the locking element (56).

2. Internal combustion engine according to claim 1, characterized by a

Return blocking element (1 12), which together with the blocking element (56) in the

Locking recess (70) can intervene.

3. Internal combustion engine according to claim 2, characterized in that the

Return blocking element (1 12) is provided with an inclined surface such that this is movable out of the locking recess (70) as a result of contact with the edge of the locking recess (70).

4. Internal combustion engine according to one of the preceding claims, characterized by a first blocking element (56) of the locking device (52), by means of which the eccentric sleeve (40) in a first Drehrerichtung with respect to the connecting rod (22) can be blocked, and a second blocking element (56) the locking device (52), by means of which the eccentric sleeve (40) in a second Drehrerichtung with respect to the connecting rod (22) can be blocked.

5. Internal combustion engine according to claim 4, characterized in that the first blocking element (56) and the second blocking element (56) by means of a common actuating element (64) are actuated alternately.

6. Internal combustion engine according to claim 5, characterized in that the

Actuator (64) is pivotable about a pivot pin, which is part of a screw (78), with the two connecting rod eye (26) forming parts of the connecting rod (22) are connected.

7. Internal combustion engine according to claim 5 or 6, characterized in that the actuating element (64) can be secured in position in its actuating end positions by means of a safety catch (80).

8. Internal combustion engine according to one of claims 5 to 7, characterized in that the actuating element (64) by means of an actuating rail (90) is actuated, which is pivotally mounted thereto to a housing of the internal combustion engine.

9. Internal combustion engine according to claim 8, characterized in that the

Actuating rail (90) forms a both sides arcuately tapered guide groove (94) for the actuating element (64).

10. Internal combustion engine according to claim 7 and claim 8 or 9, characterized

in that the safety catch (80) is designed such that the

Actuator (64) does not contact the operating rail (90) in the operating end positions.

1 1. Internal combustion engine according to one of claims 4 to 10, characterized in that

in one of the rotational orientations of the eccentric sleeve (40) relative to the connecting rod (22), the second blocking element (56) is held in a release position by means of the actuating element (64), while the first blocking element (56) is connected by means of one between the

Locking elements (56) supported spring element (62) is acted upon in a locking position, and

- In another of the Drehausrichtungen the eccentric sleeve (40) relative to the connecting rod (22) the first locking element (56) by means of the actuating element (64) is held in a release position, while the second locking element (56) by means of

Spring element (62) is acted upon in a locking position.

12. Internal combustion engine according to one of the preceding claims, characterized by a coupling device (100), by means of which the eccentric sleeve (40) is temporarily coupled to the crankshaft (14) to rotate the eccentric sleeve (40) relative to the connecting rod (22).