Actuating device for changeover valves of an internal combustion engine and internal combustion engine

Abstract

Actuating device (11) for changeover valves (10) of an internal combustion engine with adjustable compression ratio, wherein each changeover valve serves to control a hydraulic oil flow in hydraulic chambers of an eccentric adjusting device of a respective connecting rod of the internal combustion engine, and wherein each changeover valve has a tap (12) that can be actuated by the actuating device (11), wherein the actuating device (11) has a switching fork (13) with opposing switching fork legs (13a, 13b) for each changeover valve and thus for each tap (12) to be actuated, and wherein each of the switching fork legs (13a, 13b) of each switching fork (13) is contoured on a side facing the respective tap and forming a forward functional surface (21) and a return functional surface (22), wherein between the forward functional surface (21) and the return functional surface (22) of the respective shift fork leg (13a,13b) a transition surface (23) is formed, characterized in that the forward functional surface (21) and the return functional surface (22) of the respective shift fork leg (13a, 13b) each have an end face (24, 25) on a side facing away from the transition surface (23), which are chamfered on a crankshaft-facing section (24a, 25a) compared to a crankshaft-away section (24b, 25b), so that the forward functional surface (21) and the return functional surface (22) are shortened on the crankshaft-facing section (24a, 25a) compared to the crankshaft-away section (24b, 25b), the transition surface (23) is triangularly contoured and has a shorter extent between the forward functional surface (21) and the The return functional surface (22) has a section (23b) of the same opposite the crankshaft.

Description

The present invention relates to an actuator for changeover valves of a variable compression ratio internal combustion engine and a variable compression ratio internal combustion engine.In internal combustion engines, a high compression ratio has a positive effect on efficiency. The compression ratio is understood to mean the ratio of the total cylinder space before compression to the remaining cylinder space after compression. In internal combustion engines with spark ignition, such as in spark ignition engines which generally have a fixed compression ratio, however, the compression ratio must only be selected to be so high that a so-called "knocking" is avoided during full-load operation. However, for the much more frequently occurring partial load range of the internal combustion engine, i.e. with a low cylinder charge, the compression ratio could be selected with higher values without a "knocking" occurring. The important partial load range of an internal combustion engine can be improved if the compression ratio is variably adjustable.DE 10 2010 016 037 A1 discloses an internal combustion engine having an adjustable compression ratio. Connecting rods which have a stroke bearing eye and a connecting rod bearing eye can be connected to a crankshaft via the stroke bearing eye and to a respective cylinder piston of the internal combustion engine via the connecting rod bearing eye. Each connecting rod is assigned an eccentric adjusting device, which has an eccentric body and eccentric rods.The eccentric body known from DE 10 2010 016 037 A1 has a piston pin bore with a center point, which is arranged eccentrically with respect to a center point of the connecting rod bearing eye, wherein the piston pin bore accommodates a piston pin. The eccentric adjusting device serves for adjusting an effective connecting rod length leff, wherein the connecting rod length is to be understood as the distance of the center point of the piston pin bore from a center point of the stroke bearing eye. For rotating the eccentric body and thus for changing the effective connecting rod length leff, the eccentric rods of the eccentric adjusting device can be displaced. Each eccentric rod is assigned a piston which is mounted or guided displaceably in a hydraulic chamber. A hydraulic pressure prevails in the hydraulic chambers, which acts on the pistons assigned to the eccentric rods, wherein the displacement of the eccentric rods is possible or is not possible depending on the amount of oil in the hydraulic chambers.The adjustment of the eccentric adjusting device is initiated by the action of mass and load forces of the internal combustion engine, which act on the eccentric adjusting device during a working stroke of the internal combustion engine. During a working stroke, the directions of action of the forces acting on the eccentric adjusting device continuously change. The adjusting movement is supported by the pistons acted upon by hydraulic oil and acting on the eccentric rods, wherein the pistons prevent a resetting of the eccentric adjusting device due to varying force action directions of the forces acting on the eccentric adjusting device. The eccentric rods, which cooperate with the pistons, are connected to the eccentric body on both sides.The hydraulic chambers, in which the pistons are guided, can be acted upon or filled with hydraulic oil from the stroke bearing eye via hydraulic oil inlet lines and. Check valves prevent the hydraulic oil from flowing back from the hydraulic chambers into the hydraulic oil supply lines. A changeover valve is accommodated in a bore of the respective connecting rod. The hydraulic chambers are in contact with the bore which receives the changeover valve via hydraulic oil outlet lines. The switching position of the changeover valve determines which of the hydraulic chambers is filled with hydraulic oil and which of the hydraulic chambers is emptied, wherein the adjusting direction or the direction of rotation of the eccentric adjusting device depends thereon.The switching valve known from DE 10 2010 016 037 A1 comprises an actuating element, a restoring spring and a control piston.As stated, the hydraulic oil which acts on the pistons of the eccentric rods guided in the hydraulic chambers is supplied to the hydraulic chambers from the lifting bearing eye via the hydraulic oil feed lines, wherein the respective connecting rod acts with the lifting bearing eye on the crankshaft in such a way that a connecting rod bearing shell is arranged between the crankshaft, namely a crankshaft bearing journal thereof, and the lifting bearing eye.The hydraulic chambers can be vented via the hydraulic oil outlet lines depending on the switching position of the changeover valve. The adjustment direction or rotation direction of the eccentric adjustment device depends on this.DE 10 2012 112 461 A1 describes a further internal combustion engine having an adjustable compression ratio, in which the connecting rod length of the connecting rods is variably adjustable. In a bore of the respective connecting rod, a changeover valve is again accommodated, which comprises an attacker. The respective changeover valve can be actuated via the gripper, namely via an actuating device which engages on the gripper.WO 2014 / 019 684 A1 discloses an actuating device for switching valves of an internal combustion engine with an adjustable compression ratio. The actuating device comprises a shift fork for each switching valve and thus for each gripper to be actuated. Each shift fork comprises opposing shift fork legs, wherein the shift fork legs of the shift forks are contoured on the sides facing the respective catcher, forming a forward-flow functional surface and a reverse-flow functional surface. Between the forward-movement function surface and the return-movement function surface of each shift fork limb of each shift fork, a transition edge is formed which separates the respective forward-movement function surface and the respective return-movement function surface from one another in a line-like manner.DE 10 2015 224 157 A1 discloses actuating device for switching valves of an internal combustion engine according to the preamble of claim 1.US 2013 / 0 247 879 A1 discloses a further prior art.There is a need for an actuating device for the changeover valves of an internal combustion engine with an adjustable compression ratio which, with a simple design, permits reliable actuation of the changeover valves of an internal combustion engine.It is an object of the invention to provide a novel actuator for the changeover valves of an internal combustion engine with an adjustable compression ratio and an internal combustion engine with such an actuator.This object is achieved by an actuating device according to claim 1.According to the invention, a transition surface is formed between the respective forward-flow functional surface and the respective reverse-flow functional surface of the respective shift fork limb. The forward-flow function surface and the return-flow function surface are not separated from one another by a line-like transition edge, but rather by forming a flat or region-like transition surface. This allows a more reliable actuation of the grippers of the changeover valves of an internal combustion engine with an adjustable compression ratio.According to the invention, the respective forward-flow functional surface and the respective return-flow functional surface of the respective shift fork limb have end faces on a side facing away from the transition surface, which end faces run in a beveled manner on a section facing the crankshaft in relation to a section facing away from the crankshaft, such that the forward-flow functional surface and the return-flow functional surface are shortened on the section facing towards the crankshaft in relation to the section facing away from the crankshaft. This also serves to increase the reliability in the actuation of the grippers of the changeover valves of the internal combustion engine with an adjustable compression ratio.According to the invention, the transition surface is triangularly contoured and has a short extension between the forward functional surface and the return functional surface at a section thereof facing the crankshaft than at a section thereof facing away from the crankshaft. This can further increase the reliability in the actuation of the grippers of the switching valves.Preferably, the forward-flow function surface and the return-flow function surface of the respective shift fork limb are contoured independently of one another and / or are tilted in space about axes in such a way that a movement path of a contact point of the respective gripper along the function surfaces runs in the region of the end sides thereof facing away from the transition surface through the sections of the end sides facing away from the crankshaft. This allows particularly reliable actuation of the grippers of the changeover valves of an internal combustion engine with an adjustable compression ratio.The gripper of the respective changeover valve is preferably cylindrical with end faces contoured in the manner of a spherical or spherical segment at lateral sections or ends thereof. At least the forward-flow functional surfaces and optionally also the backward-flow functional surfaces of the respective shift fork are preferably contoured and / or tilted in space in such a way that the contact point of the respective attacker with the respective functional surface of the respective shift fork always lies on one of these spherical or ball-segment-like end faces of the attacker. This also allows reliable actuation of the grippers of the changeover valves of an internal combustion engine with an adjustable compression ratio.The internal combustion engine with an adjustable compression ratio according to the invention is defined in claim 8.Preferred developments of the invention are evident from the dependent claims and the following description. Exemplary embodiments of the invention are explained in more detail with reference to the drawings, without being restricted thereto. The following shows: FIG. 1 shows a connecting rod with an eccentric adjusting device and a changeover valve; FIG. 2 shows an actuating device according to the invention for switching valves of the connecting rods; FIG. 3 shows a shift fork of the actuating device according to the invention from FIG. 2 ; FIG. 4 shows a shift fork limb of the shift fork of FIG. 3 ; and FIG. 5 shows a shift fork together with an gripper of a changeover valve.FIG. 1 shows a connecting rod 1 of an adjustable compression ratio internal combustion engine according to an embodiment.The connecting rod 1 has a connecting rod base body 7 with a connecting rod bearing eye 2 and a stroke bearing eye 3. The connecting rod bearing eye 2 serves for connecting the respective connecting rod 1 to a cylinder piston (not shown) of a respective cylinder of the internal combustion engine. The crankshaft bearing eye 3 serves for connecting the respective connecting rod 1 to a crankshaft (not shown) of the internal combustion engine.The connecting rod 1 of FIG. 1 has a preferably hydraulically adjustable eccentric adjustment device 6 arranged at least in sections in the connecting rod bearing eye 2. The eccentric adjusting device 6 has a piston pin bore, which is arranged eccentrically with respect to a central axis 8 of the connecting rod bearing eye 2 and has a central axis which accommodates a piston pin (not shown). The respective connecting rod 1 is coupled to the cylinder piston of the respective cylinder via the piston pin.The eccentric adjusting device 6 serves for adjusting an effective connecting rod length leff of the connecting rod 1. a rotation of the adjustable eccentric adjusting device 6 is initiated by the action of mass and load forces of the internal combustion engine, which act on the eccentric device 6 during a working stroke of the internal combustion engine.During a working stroke, the directions of action of the forces acting on the eccentric device 6 change continuously. The rotational movement or adjusting movement is supported by pistons which are acted upon by hydraulic fluid, in particular by engine oil, are integrated in the connecting rod arrangement 1 and are guided in hydraulic chambers, or the pistons prevent the eccentric adjusting device 6 from being reset on account of varying force action directions of the forces acting on the eccentric adjusting device 6.The pistons of the eccentric adjusting device 6 are operatively connected on both sides to an eccentric body 9 of the eccentric adjusting device 6 by means of eccentric rods 4, 5. The eccentric adjusting device 6 can have the pistons, the eccentric rods 4, 5 and the eccentric body 9. The pistons of the eccentric adjusting device 6 are acted upon with hydraulic fluid from the stroke bearing eye 3 via hydraulic fluid lines not shown in FIG. 1 via check valves not shown in FIG. 1.The check valves prevent a return flow of the hydraulic fluid from the piston volumes of the pistons back into the hydraulic fluid lines into an engine interior of the internal combustion engine.A changeover valve 10 is accommodated in a bore of the respective connecting rod 1. The hydraulic chambers of the eccentric adjusting device 6 of the respective connecting rod 1 are in contact via hydraulic fluid lines with the bore which accommodates the changeover valve 10. The switching position of the switching valve 10 determines which of the hydraulic chambers is filled with hydraulic oil and which of the hydraulic chambers is emptied, wherein the adjusting direction or the direction of rotation of the eccentric adjusting device 6 depends thereon.The respective changeover valve 10 of the respective connecting rod 1 has an gripper 12. The respective changeover valve 10 can be actuated via the gripper 12, namely via an actuating device 11 which engages on the gripper 12.The present invention relates to details of the actuating device 11 for such an internal combustion engine with a variably adjustable compression ratio, namely an actuating device 11 which serves for actuating the grippers 12 of the changeover valves 10 of a plurality of connecting rods 1. The actuating device 11 for actuating a plurality of switching valves 10 of an internal combustion engine with an adjustable compression ratio has a plurality of shift forks 13, wherein each of the shift forks 13 interacts in each case with a gripper 12 of in each case one switching valve 10 to be actuated. All the shift forks 13 are preferably fastened to a common support structure 14.The support structure 14 of the actuating device 11 has a mounting frame 15 and at least one guide element 16, which is common to all the shift forks 13 and is displaceable relative to the mounting frame 15.In the exemplary embodiment shown, the guide element 16 has two guide rails 17, 18 running parallel to one another, which are firmly connected to one another via a connecting web 19. A plurality of shift forks 13 are fastened to each guide rail 17, 18 of the guide element 16.The entire actuating device 11 can be mounted on the crankcase (not shown) of the internal combustion engine via the mounting frame 15, namely via mounting screws, not shown, which extend through mounting openings 20 in the mounting frame 15.As already stated, the guide element 16 of the actuating device 11 to which the shift forks 13 are fastened can be displaced relative to the mounting frame 15, namely in the direction of the double arrow 26.As a result of this relative movement of the shift forks 13 of the actuating device 11 relative to the mounting frame 15 thereof, when during a working stroke of a cylinder the switching valve 10 integrated into the respective connecting rod 1 of the respective cylinder has moved into the region of the respective shift fork 16 of the actuating device 15, the gripper 12 of the respective switching valve 10 can be actuated in order to actuate the same.The shift forks 13 of the actuating device 11 can accordingly be displaced together with the aid of the guide element 16 of the support structure 14 which is common for all the shift forks in the exemplary embodiment shown and to which the shift forks 13 are fastened, relative to the mounting frame 15 of the support structure 14 and thus relative to the grippers 12 of the switching valves 10, namely between a first switching position of the shift forks 13 and a second switching position of the shift forks 13.By means of the shift forks 13 of the actuating device 11, a defined shift position of the switching valves 10 of the connecting rods 1 of the internal combustion engine with an adjustable compression ratio can be set in the respective shift position.The displacement of the shift forks 13 of the actuating device 11 from the first shift position into the second shift position is preferably effected with the aid of an actuator, not shown, wherein all the shift forks 13 can be displaced jointly from the first shift position into the second shift position counter to the restoring force, in particular the spring force, of a restoring element, preferably common to all the shift forks 13 and preferably embodied as a spring element, likewise not shown.The restoring force, in particular the spring force, of the restoring element, which is preferably designed as a spring element, presses all the shift forks 13 jointly and automatically out of the second shift position in the direction of the first shift position, namely when the actuator is not active.Each shift fork 13 comprises opposing shift fork legs 13 a, 13 b. In this case, each shift fork limb 13 a, 13 bof each shift fork 13 provides, on a side facing the respective gripper 12, both a forward-movement function surface 21 and a return-movement function surface 22, which cooperate with the gripper 12 in such a way that the gripper 12 can move along these function surfaces 21, 22 by means of a contact point 28 (see FIG. 5 ).The gripper 12 of the respective changeover valve 10 is preferably cylindrical with end faces contoured spherically or in the manner of a spherical segment on lateral sections thereof.According to the invention, a transition surface 23 is formed between the forward-movement functional surface 21 and the reverse-movement functional surface 22 of the respective shift fork limb 13 a, 13 bof each shift fork 13.The forward-flow function surface 21 and the rearward-flow function surface 22 of each shift fork limb 13 a, 13 btherefore do not merge into one another in a line-like manner, as is customary in the prior art, forming a transition edge, but rather merge into one another in a planar or region-like manner, forming the transition surface 23.As can be seen in particular from FIGS. 3 and 4, the transition surface 23 formed in the region of each shift fork limb 13 a, 13 bof the shift fork is contoured in the manner of a triangle.As can best be seen from FIGS. 3 and 4, the forward-flow function surface 21, like the return-flow function surface 22 of the respective shift fork limb 13 a, 13 b, has a respective end face 24 or 25 on a side facing away from the transition surface 23, namely the forward-flow function surface 21 has the end face 25 and the return-flow function surface 22 has the end face 24. these end faces 24 and 25 are designed such that they run in a beveled manner on a crankshaft-facing section 24 aand 25 arelative to a crankshaft-facing section 24 b, 25 b, so that accordingly both the forward-flow function surface 21 and the return-flow function surface 22 on the crankshaft-facing sections 24 a, 25 aare shortened relative to the crankshaft-facing sections 24 b, 25 b. FIGS. 3 and 4 also show that the transition surface 23 has a shorter extension between the forward-flow function surface 21 and the return-flow function surface 22 at a portion 23 athereof facing the crankshaft than a portion 23 bthereof facing away from the crankshaft. Starting from the section 23 bfacing away from the crankshaft, the transition surface 23 accordingly narrows in the direction of the section 23 afacing the crankshaft thereof.The advance function surface 21 and the return function surface 22 of each shift fork limb 13 a, 13 bof each shift fork 13 are contoured independently of one another. Preferably, the forward-movement functional surfaces 21 and the return-movement functional surfaces 22 are each planes which are freely tilted in space about at least two axes, wherein the tilting of the forward-movement functional surface 21 and of the return-movement functional surface 22 of the respective shift fork limb 13 a, 13 bof each shift fork 13 takes place independently of one another in space.The contouring and / or tilting of the forward-flow functional surface 21 and of the reverse-flow functional surface 22 of the respective shift fork limb 13 a, 13 bis preferably effected in such a way that the movement path 27 of the contact point 28 of the respective gripper 12 extends along the functional surfaces 21, 22 in such a way that the movement path 27 extends in the region of the end faces 24, 25 of the functional surfaces 21, 22 facing away from the transition surface 23 through the sections 24 b, 25 bof the end faces 24, 25 facing away from the crankshaft, so that accordingly the functional surfaces provided by the shift forks 13 or shift fork limbs 13 a, 13 bcan be optimally utilized, namely maximally, in terms of their length for the movement path 27 of the contact point 28 of the respective gripper 12. It is thus avoided that the contact path 27 of the respective contact point 28 of the respective gripper 12 extends through the beveled sections 24 a, 25 aof the end faces 24, 25 facing the crankshaft of the forward function surface 21 and the return function surface 22, so that accordingly the movement path 27 is spaced apart from the sections 24 a, 24 bof the end faces 24, 25 facing the crankshaft.The gripper 12 of the respective changeover valve 10 is preferably cylindrical with end faces which are preferably contoured in the manner of a spherical or spherical segment at lateral sections or ends thereof. At least the forward-flow function surfaces 21 and optionally also the return-flow function surfaces 22 of the respective shift fork 13 are preferably contoured and / or tilted in space in such a way that the contact point 28 of the respective attacker 12 with the respective function surface 21, 22 of the respective shift fork 13 always lies on one of these spherical or ball-segment-like end faces of the attacker 12.The gripper 12 is preferably a cylindrical pin and has a diameter d. The gripper 12 is preferably contoured in the manner of a spherical segment with a spherical radius r on its lateral end faces which interact with the functional surfaces of the respective shift fork 13.At least the forward-movement functional surface 21 and, if possible depending on the installation space present, also the rearward-movement functional surface 22 of the respective shift fork limb 13 a, 13 bof the respective shift fork 13 is contoured and / or tilted in such a way that the gradient angle of the respective functional surface is smaller than arcsin((d / 2) / r). It can then be ensured in a particularly preferred manner that the contact point 28 of the respective gripper 12 with the respective functional surface 21, 22 of the respective shift fork 13 is always located on the ball segment-like end face of the gripper 12. As already stated, at least the advance function surfaces 21 are preferably contoured in such a way. This is also preferred in the region of the return function surfaces 22. For the return function surfaces 22, however, for reasons of installation space, in favor of the forward function surfaces 21, a different contouring and / or tilting can also be selected, namely in such a way that the contact point 28 of the respective attacker 12 with the respective return function surface 22 of the respective shifting fork 13 lies on an edge of the attacker 12.Accordingly, the invention proposes a defined contouring of the shift fork legs 13 a, 13 bof each shift fork 13 of the actuating device 11 for switching valves 10 of an internal combustion engine with an adjustable compression ratio.The sides of the shift fork legs 13 a, 13 bfacing the grippers 12, namely the lateral end faces of the grippers 12, are contoured to form forward-flow functional surfaces 21 and return-flow functional surfaces 22, wherein in the region of each shift fork leg 13 a, 13 bof the respective shift cable 13 the respective forward-flow functional surface 21 and the respective return-flow functional surface 22 are designed independently of one another, and wherein a transition surface 23 is positioned between them.The forward-movement function surface 21 and the return-movement function surface 22 are contoured or inclined in space in the region of each shift fork limb 13 a, 13 bin such a way that a defined movement path 27 of the contact point 28 of the respective attacker 12 along the function surfaces 21, 22 is provided in order to enable reliable guidance and thus actuation of the attacker 12, wherein this movement path 27 extends through the sections 24 b, 25 bof the end faces 24, 25 of the function surfaces 21, 22 of the respective shift fork limb 13 aand 13 b,facing away from the crankshaft. It is thus avoided that the movement path 27 of the contact point 28 of the respective gripper 12 extends through beveled sections 24 a, 25 aof these end faces 24, 25 of the functional surfaces 21, 22 facing the crankshaft, which sections are beveled and shortened accordingly to avoid a collision with the crankshaft.Preferably, at least the pre-running function surface 21 is further contoured in the region of each shifting fork limb 13 a, 13 bin such a way that the contact point 28 between the gripper 12 and the pre-running function surface 21 is always located on the spherical or ball segment-like end face of the gripper 12.FIG. 2 shows that the actuating device 11 shown there, with the example number of six shift forks 13, has two groups of three shift forks 13 each, wherein the forward-flow function surfaces 21 are positioned above the backward-flow function surfaces 22 on the left group of 13 shift forks shown in FIG. 2, and the forward-flow function surfaces 21 are positioned below the backward-flow function surfaces 22 on the right group of shift forks 13 shown in FIG. 2. This depends on the direction of rotation of the crankshaft.

Claims

Actuating device (11) for switching valves (10) of an internal combustion engine with an adjustable compression ratio, wherein each switching valve serves for controlling a flow of hydraulic oil in hydraulic chambers of an eccentric adjusting device of a respective connecting rod of the internal combustion engine, and wherein each switching valve has an engagement device (12) which can be actuated by the actuating device (11), wherein the actuating device (11) has, for each switching valve and thus for each engagement device (12) to be actuated, a switching fork (13) having mutually opposite switching fork limbs (13a, 13b), and wherein each of the switching fork limbs (13a, 13b) of each switching fork (13) is contoured on a side facing the respective engagement device and forming a forward-flow functional surface (21) and a reverse-flow functional surface (22), wherein a transition surface (23) is formed between the forward-flow functional surface (21) and the return-flow functional surface (22) of the respective shift fork limb (13a, 13b), characterized in that the forward-flow functional surface (21) and the return-flow functional surface (22) of the respective shift fork limb (13a, 13b) each have an end face (24, 25) on a side facing away from the transition surface (23), which ends face extend obliquely on a portion (24a, 25a) facing towards the crankshaft in relation to a portion (24b, 25b) facing away from the crankshaft, such that the forward-flow functional surface (21) and the return-flow functional surface (22) are shortened on the portion (24a, 25a) facing towards the crankshaft in relation to the portion (24b, 25b) facing away from the crankshaft, the transition surface (23) is triangularly contoured and has a short extension between the forward function surface (21) and the rearward function surface (22) at a portion (23a) thereof facing the crankshaft than at a portion (23b) thereof facing away from the crankshaft.Actuating device according to Claim 1, characterized in that the forward-movement functional surface (21) and the rearward-movement functional surface (22) of the respective shift fork limb (13a, 13b) are contoured independently of one another and / or are tilted in space about axes in such a way that a movement path (27) of a contact point (28) of the respective gripper (12) runs along the functional surfaces (21, 22) in the region of the end faces (24, 25) thereof which are remote from the transition surface (23) through the sections (24b, 25b) of the end faces (24, 25) which are remote from the crankshaft.Actuating device according to one of Claims 1 to 2, characterized in that the advance function surface (21) and the return function surface (22) of the respective shift fork limb (13a, 13b) are contoured independently of one another.Actuating device according to one of Claims 1 to 3, characterized in that the forward-movement functional surface (21) and the return-movement functional surface (22) of the respective shift fork limb (13a, 13b) are planes which are tilted in space about at least two axes.Actuating device according to Claim 4, characterized in that the advance function surface (21) and the respective return function surface (22) of the respective shift fork limb (13a, 13b) are tilted independently of one another in space about the axes.Actuating device according to one of Claims 1 to 5, characterized in that at least the lead-in function surface (21) is contoured in such a way that a contact point (28) between the gripper (12) and the lead-in function surface (21) is always located on a spherical or ball-segment-like end face of the gripper (12).Actuating device according to Claim 6, characterized in that a pitch angle of at least the lead-in functional surface is less than arcsin((d / 2) / r), wherein r is the radius of the ball-segment-like end face of the gripper (12), and wherein d is the diameter of the cylindrical gripper (12).Internal combustion engine which has an adjustable compression ratio, having a plurality of connecting rods (1) which each have a hydraulically adjustable eccentric adjustment device (6) arranged in a connecting-rod bearing eye (2) and / or a stroke bearing eye (3) for adjusting an effective connecting-rod length (leff) of the respective connecting-rod bearing eye (2), wherein an adjustment travel of the eccentric adjustment device (6) can be controlled by means of a changeover valve (10), characterized in that the changeover valves (10) can be actuated by an actuating device (11) according to one of Claims 1 to 7.

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