DE102011018397A1 - Method for operating an internal combustion engine and adjusting device for variably setting at least one compression ratio of such an internal combustion engine - Google Patents

Abstract

The invention relates to a method for operating an internal combustion engine (98), in particular a reciprocating piston internal combustion engine (98), with at least one variably adjustable compression ratio, in which a movement of at least one transmission element (12, 44, 46, 48, 50 , 52), by means of which the compression ratio can be set, in a first direction of movement and / or in a second direction of movement opposite to the first direction of movement by means of at least one actuator (24), with the step: switching of the brake device (24) Actuator (24) for effecting the movement of the transmission element (12, 44, 46, 48, 50, 52) in the first or the second direction of movement from a braking state which prevents the movement and at least substantially maintains the compression ratio into a release state which enables the movement, if a force and / o a torque acting at least indirectly on the transmission element (12, 44, 46, 48, 50, 52), which causes movement of the transmission element (12, 44, 46, 48, 50, 52) in the first or second direction of movement to set the Compression ratio causes, and an adjusting device (42) for variably setting at least one compression ratio of an internal combustion engine (98).

Description

The invention relates to a method for operating an internal combustion engine specified in the preamble of claim 1. Art and an adjusting device for variably setting at least one compression ratio of an internal combustion engine specified in the preamble of claim 6. Art.

The DE 196 27 145 C2 discloses a coupling with a shaft, an associated hollow shaft and a coil spring arranged between them. It is provided that the wrap spring is electrically actuated, being mounted on the wrap spring piezoelectric elements, or being integrated in the wrap spring piezoelectric elements to induce a change in shape to open or close the wrap spring electrically. Likewise, a clutch with a drive and an output shaft is known from this publication, wherein the input and / or output shaft has a coating with piezo elements to vary by pressing the piezo elements, the scope of the input and / or output shaft ,

It is the object of the present invention to provide a method for operating an internal combustion engine having at least one variably adjustable compression ratio and an adjusting device for variably setting at least one compression ratio of such an internal combustion engine, by means of which a particularly low fuel consumption of the internal combustion engine is made possible.

This object is achieved by a method for operating an internal combustion engine having at least one variably adjustable compression ratio with the features of patent claim 1 and by an adjusting device for variably setting at least one compression ratio of such an internal combustion engine having the features of patent claim 6. Advantageous embodiments with expedient and non-trivial developments of the invention are specified in the remaining claims.

The first aspect of this invention relates to a method of operating an internal combustion engine, in particular a reciprocating internal combustion engine, with at least one variably adjustable compression ratio, in which a movement of at least one transmission element is effected for adjusting the compression ratio. About the transmission element, the compression ratio is adjustable. The transmission element, which is assigned to an adjusting device for adjusting or adjusting the compression ratio, serves to transmit forces and / or torques so as to be able to adjust or adjust the compression ratio.

In the method, a movement of the transmission element in a first direction of movement and / or in a second direction of movement opposite to the first direction of movement is moved by means of at least one actuator of the adjusting device.

According to the invention, a braking device is used as the actuator. The braking device is thereby switched to effect the movement of the transmission element in the first or the second direction of movement from a braking state to a release state. In the braking state, the movement of the transmission element is prevented, so that the set compression ratio is kept at least substantially constant. In the release state, the transmission element is released, so that it can be moved to adjust the compression ratio, for example relative to a bearing element on which the transmission element is mounted relative to this movable.

The switching of the braking device from the braking state to the release state takes place in the method according to the invention when a force and / or torque acts at least indirectly on the transmission element, wherein the force and / or the torque a desired movement of the transmission element in the first or second Direction of movement for adjusting the compression ratio causes. Preferably, in the method according to the invention, only the braking device is used as the actuator in order to effect adjustment or adjustment of the compression ratio exclusively by means of the braking device.

In the adjusting device according to the invention thus an at least substantially passive adjustment or adjustment of the compression ratio is realized. This means that for setting or adjusting the compression ratio, the transmission element is not actively moved and, accordingly, no energy has to be expended for actively moving the transmission element. Rather, the already acting forces and / or the already acting torques, which act for example from the inertia forces and from the combustion chamber on the adjusting device, in particular the transmission element and which, for example, resulting from acceleration processes of the engine parts and combustion processes in the combustion chamber, so that the transmission element is moved taking advantage of these already existing and acting forces or torques.

In this case, the braking device is only to be supplied with energy, for example electrical current, in order to switch it between the release state and the braking state. In this case, it can be provided that the braking device is supplied with energy for switching it from the braking state in the release state and / or from the release state into the braking state. It is particularly preferably provided that the braking device is only supplied with energy for switching it from the release state into the braking state (but not vice versa) or only for switching it from the braking state into the release state (but not vice versa). This supply of braking device for effecting the movement of the transmission element is compared to the energy required for actively moving the transmission element in the first or second direction of movement substantially lower, so that by means of the inventive method, the compression ratio can be adjusted or adjusted with only a very small amount of energy. This keeps the energy requirement of the adjusting device low, which is associated with fuel consumption and thus low CO ₂ emissions of the internal combustion engine.

In the method according to the invention thus additional, and in particular actuators for actively moving the transmission element and adjusting elements are not provided and not required, but may nevertheless be present. Thus, the compression ratio can be adjusted or adjusted with simple means and with a very low energy requirement. Furthermore, this can be kept low, the number of parts, the weight, the cost and the space requirement of the adjusting device and thus the entire internal combustion engine. This leads in particular to the avoidance and / or the solution of package problems, in particular in a space-critical area such as an engine compartment of a motor vehicle, in particular of a passenger car.

As already indicated, the force and / or the torque used to move the transmission element for setting or adjusting the compression ratio results, for example, from burns (see above) which take place in the combustion chamber with the variably adjustable compression ratio. The internal combustion engine is designed for example as a reciprocating internal combustion engine, which has the at least one combustion chamber in the form of a cylinder. In the cylinder, a piston is translationally relative to the cylinder slidably received. The piston is pivotally coupled to a connecting rod, which is articulated, for example, with a transverse lever of the adjusting device. The transverse lever is rotatably mounted relative to the crank pin on a crank pin of a crankshaft of the reciprocating internal combustion engine. The one hand articulated coupled with the connecting rod transverse lever is on the other hand at least indirectly connected to an adjusting shaft as the transmission element of the adjusting articulated. For this purpose, for example, a Nebenpleuel is provided which is coupled on the one hand articulated to the transverse lever and on the other hand articulated with the adjusting.

The adjusting shaft is formed for example as an eccentric shaft and comprises at least one eccentric on which the Nebenpleuel is rotatably mounted relative to the eccentric. The adjusting shaft is rotatably mounted on the housing part about an axis of rotation relative to a housing part of the adjusting device and / or the internal combustion engine. A rotation of the adjusting shaft about the axis of rotation causes a rotation of the transverse lever relative to the crank pin, which in turn causes a translational displacement of the piston in the cylinder relative thereto. As a result, the compression ratio can be adjusted and adapted as needed to thermodynamic requirements of the reciprocating internal combustion engine.

From this it can be seen that forces, in particular resulting from the inertial forces and combustion processes in the cylinder via the piston and the connecting rod and the transverse lever and the Nebenpleuel can act on the adjusting shaft, which is the transmission element of the adjusting device. The adjusting shaft is rotatable for adjusting the compression ratio about its axis of rotation in a first direction of rotation than the first direction of movement, and in a second direction of rotation, the first direction of rotation opposite direction of rotation as the second direction of movement.

If an adjustment of the compression ratio of a first to a different second value is provided, wherein the second value is set, for example by turning the adjusting shaft in the first direction of rotation, and the force acting on the adjusting shaft and / or torque would be the adjusting shaft in the release state of Turning brake device in this first direction of rotation, the brake device is switched from the rotation of the adjusting about its axis of rotation relative to the housing part preventing braking state in the release state, so that the acting force and / or the torque acting actually rotate the adjusting shaft in the first direction can. As a result, the already acting force and / or the already acting torque is used to at least substantially passively rotate the adjusting shaft, without actively rotating the adjusting shaft by means of a separate adjusting device about its axis of rotation.

The braking device allows in particular the backlash-free support particularly high and in particular changing torques, so that the set compression ratio can be secured against these high torques against undesirable points due to the high torque and kept at least substantially constant at a desired value. The play-free holding and fixing of the transmission element, in particular the adjusting shaft, thereby ensuring a particularly quiet operation and low-noise operation of the internal combustion engine, which benefits the ride comfort.

Preferably, the braking device is electrically actuated. As a result, it is particularly fast, that is, in a particularly short time, switchable between the release state and the braking state. Thus, a particularly frequent adjustment of the compression ratio can also be effected in a particularly short period of time.

In a particularly advantageous embodiment, the braking device comprises at least one piezo-actuator, which comprises, for example, a piezo-stack with piezo-elements. As a result, the braking device has only a very small space requirement and only a very low energy consumption, which keeps the space requirement and the energy consumption of the entire internal combustion engine particularly low. The piezoelectric actuator also has a low inertia, which is why the piezoelectric actuator can be switched particularly fast, that is, in a particularly short time, between the braking state and the release state.

If the force acting on the transmission element, in particular the adjusting shaft, and / or the corresponding torque would cause the transmission element to move in an undesired direction of movement, which would be accompanied by an adjustment of an undesired compression ratio or an undesired value of the compression ratio, then the braking device is moved into the Switched brake state, that is, the braking device is closed. As a result, the transmission element is not moved in this undesired direction of movement. If the force or the torque would cause the transmission element to move in a desired direction of movement, then the braking device is switched to the release state. That is, the braking device is opened so that the force and / or the torque can move the transmission element in the desired direction of movement. Thus, the movement in the desired direction of movement of the transmission element is effected or prevented by means of the braking device.

In an advantageous embodiment of the invention, the forces acting on the transmission element and / or the torques are detected by means of at least one detection device. Through this detection, it can be determined whether the acting force and / or the torque would move the transmission element fixed by means of the braking device switched into the braking state into a desired or undesired one of the directions of movement when the braking device was in the release state. If it is detected by means of the detection device that the force and / or the torque (see above) acts and the transmission element would move in the release state of the braking device in the desired direction of movement, the braking device is switched to the release state, so that the force and / or Torque (see above) actually moves the transmission element in the desired direction of movement.

In a further advantageous embodiment of the invention, the braking device is repeatedly switched between the braking state and the release state during a period during which the forces and / or torques causing the movement in the first or second direction of movement repeatedly change direction. In other words, for a desired movement of the transmission element in a desired one of the directions of movement over a desired movement path, the braking device is opened several times, that is to say at least twice, and accordingly closed. As a result, the compression ratio, despite the high frequency with the forces and / or torques change their direction and despite the opposing mass moments of inertia of the moving transmission elements can be adjusted over any adjustment. In particular, it may be provided that depending on a ratio of the force acting on the transmission element and / or the torque to inertia of the transmission element, in particular to the moment of inertia of the adjusting, the braking device for the movement of the transmission element over the desired path of movement away, in particular for a movement of the adjusting by a certain angular amount about its axis of rotation, repeatedly opened and closed accordingly. As a result, for example, a stepwise movement of the transmission element in the desired direction of movement, whereby the transmission element is moved very gently for the adjusting device in the desired direction of movement.

If the movement path, in particular the angle amount, is very small, it can be provided that the braking device only during a part-time range of a period of time is opened and switched to the release state, during which the force and / or the torque would cause or cause the movement of the transmission element in the desired direction of movement. The remaining period of time during which the force and / or the torque would or would cause the movement of the transmission element in the desired direction of movement, the braking device is closed. That is, it is in its braking state. This means that the transmission element could be moved by means of the force and / or the torque a particularly high path of movement. However, since a smaller moving path for setting a desired compression ratio is desired and provided, the braking means is opened only during the part-time area of the entire period. As a result, the compression ratio can be adjusted or adjusted particularly precisely and as needed.

In a particularly advantageous embodiment of the invention, the braking device is held at least temporarily after movement of the transmission element in the first direction of movement in the release state for braking the transmission element, if the force and / or the torque after the movement in the first direction of movement in counteracts the first direction of movement. In other words, the braking device can also be opened for a period of time in which the force and / or the torque moves the transmission element in the desired direction of movement and for a period of time in which the force and / or the torque causes the transmission element to move in the direction opposite to this direction of movement Direction of movement causes. In other words, the braking device is thus held over a change in sign of the force and / or torque away in the release state. This can be used to decelerate in example the first direction of movement accelerated transmission element by the changing force and / or the alternating torque without the braking device in operative connection, in particular active contact, to switch with the transmission element or to spend for braking the transmission element.

Advantageously, the braking device is then switched to the braking state when the speed of the transmission element in its movement in one of the directions of movement falls below a predefinable threshold value, in particular if the speed of the transmission element, in particular the rotational speed of the adjusting, at least substantially zero or in a vicinity to zero lies. As a result, the wear of the transmission element and thus the entire adjusting device can be kept low.

Advantageously, for precise control and / or regulation of the braking device and thus for exact movement of the transmission element temporal courses of the particular changing force and / or the particular changing torque at least substantially known in the entire map of the internal combustion engine. Additionally or alternatively, it is possible to determine the position of the transmission element along its axis of motion, trajectory and / or the like, in particular the rotational position of the adjusting about its axis of rotation, and thus the speed of the transmission element or the rotational speed of the adjusting precisely and with high temporal resolution and capture. For this purpose, for example, at least one rotary encoder is used. The time profiles of the force and / or the torque can be calculated, in particular simulated and / or determined during the development and / or production of the internal combustion engine on a test bench.

The second aspect of the invention relates to an adjusting device for variably setting at least one compression ratio of an internal combustion engine, in particular a reciprocating internal combustion engine. The adjusting device comprises at least one actuator, by means of which, for the variable setting of the compression ratio, a movement of at least one transmission element, via which the compression ratio is adjustable, the adjusting device in a first direction of movement and / or in a second, the first direction of movement opposite direction of movement is effected.

According to the invention, the actuator is designed as a braking device. For effecting the movement of the transmission element in the first or the second direction of movement, the braking device is switchable from a braking state preventing and at least substantially maintaining the compression ratio into a release state enabling the movement, if a force and / or a torque is at least indirectly on the Transmission element which causes a movement of the transmission element in the desired first or second direction of movement for adjusting the compression ratio. Advantageous embodiments of the first aspect of the invention are to be regarded as advantageous embodiments of the second aspect of the invention and vice versa.

As a result, the adjusting device allows the use of the already acting forces and / or the already acting torques for adjusting or adjusting the compression ratio, without actively moving the transmission element. The transmission element is rather passively moved in the internal combustion engine according to the invention. In other words, a passive movement of the transmission element is allowed by the braking device is switched to the release state. Thus, the compression ratio can be adjusted or adjusted in the internal combustion engine according to the invention with only a very small amount of energy, which keeps low fuel consumption and CO ₂ emissions of the internal combustion engine.

Further advantages, features and details of the invention will become apparent from the following description of preferred embodiments and from the drawing. The features and feature combinations mentioned above in the description as well as the features and combinations of features shown below in the description of the figures and / or in the figures alone can be used not only in the respectively indicated combination but also according to new combinations or alone, without the scope of the invention to leave.

The drawing shows in:

1 a schematic perspective view of a bearing assembly of a shaft on a bearing element, in which the shaft is rotatably mounted on two bearing parts about an axis of rotation relative to the bearing parts on the bearing element, wherein an actuator is provided, by means of which for fixing the shaft, relative to the bearing parts a Relative movement between the bearing parts is effected;

2 a schematic perspective view of another embodiment of the storage arrangement according to 1 ;

3 a schematic front view of the storage arrangement according to 2 ;

4 a schematic perspective view of another embodiment of the storage arrangement according to the 1 to 3 ;

5 a detail of a schematic and partially sectioned view of an adjusting device for adjusting the cylinder individual compression ratios of a reciprocating internal combustion engine;

6 three diagrams for illustrating a method for adjusting the compression ratios of the reciprocating internal combustion engine with the adjusting device according to the 1 to 5 ; and

7 three diagrams illustrating a further embodiment of the method according to the 1 to 5 ;

8th a schematic perspective view of a reciprocating internal combustion engine with an alternative embodiment of the steepening device, which the storage arrangement according to 1 includes; and

9 a schematic perspective view of the reciprocating internal combustion engine according to FIG 8th with the adjusting device, which the storage arrangement according to 2 and 3 having.

The 1 shows a storage arrangement 10 a wave 12 on a bearing element 14 in which the shaft 12 around a rotation axis 16 relative to the bearing element 14 is rotatably mounted on this. This includes the bearing element 14 a frame 18 , in particular a machine frame. The frame 18 For example, is a housing part of a housing of a reciprocating internal combustion engine, in which the shaft 12 at least partially included.

The bearing element 14 also includes a bearing cap 20 , which by means of clamping screws 22 with the frame 18 is screwed. Through the frame 18 is a first part of a bearing mount, a bearing bore, for the shaft 12 educated. Through the bearing cap 20 is a second part of the bearing support for the shaft 12 educated. Through the bearing element 14 is thus a split, especially two-part, bearing for the shaft 12 formed by which the shaft 12 on the bearing element 14 is stored. The wave 12 is at least partially in the bearing support and in the clamped state of the frame 18 with the bearing cap 20 clamped so tightly in the bearing seat, that a maximum moment, which is on the shaft 12 acts, just can still be held without the shaft 12 relative to the bearing element about its axis of rotation 16 rotates. Here is a common undersize for a press fit z. B. 1/1000 of the diameter of the bearing receiver. A necessary biasing force can be achieved by the clamping screws 22 be applied.

Between the frame 18 and the bearing cap 20 are piezo stacks 24 arranged with respective piezo elements and by means of the clamping screws 22 clamped. Is sent to the Piezo Stacks 24 applied a corresponding electrical voltage, so expand the piezo stacks 24 at least in Direction of the frame 18 and / or in the direction of the bearing cap 20 and thus perpendicular to the pitch of the bearing and set a bearing clearance of about the usual size of a sliding bearing, which is, for example, about 1/1000 of the diameter of the bearing.

In other words, it's the Piezo Stacks 24 no electrical voltage applied, so is the wave 12 by means of the clamping screws 22 between the frame 18 and the bearing cap 20 clamped and fixed relative to these, so that the shaft 12 not about its axis of rotation 16 relative to the frame 18 and to the bearing cap 20 can turn. This clamping is on the maximum occurring and on the shaft 12 during an operation of the internal combustion engine acting torque matched so that by clamping this moment can be supported and this moment the shaft is not about the axis of rotation 16 relative to the frame 18 and the bearing cap 20 can twist.

Is sent to the Piezo Stacks 24 applied an electrical voltage, so it is a relative movement between the frame 18 and the bearing cap 20 causes. The frame is moving 18 and the bearing cap 20 away from each other. This will clamp the shaft between the frame 18 and the bearing cap 20 reduced or even completely lifted, so the shaft 12 around its axis of rotation 16 relative to the frame 18 and the bearing cap 20 can be turned. Is the wave 12 in a desired rotational position about its axis of rotation 16 relative to the frame 18 and the bearing cap 20 rotated, so the application of the electrical voltage to the piezo stacks 24 canceled. This causes a relative movement of the frame 18 and the bearing cap 20 towards each other, for example due to elastic resilience of the frame 18 and the bearing cap 20 as a result of the screw connection by means of the clamping screws 20 so the wave 12 between the frame 18 and the bearing cap 20 clamped and thus relative to the bearing element 14 is fixed.

Thereby, a particularly fast to switching and at least substantially backlash-free clamping brake is provided, by means of which the shaft quickly, that is in a short time, relative to the bearing element 14 fixed or can be released accordingly. By modulating the electrical voltage can thus be a quick release and braking of the shaft 12 be achieved, as it can be done, for example, to at least in the kHz range.

Equally possible is a reversal of the respect 1 described operating principle of the clamping brake in the storage arrangement 10 possible. Here is the wave 12 in a de-energized state of the piezo stacks 24 , in which the piezo stacks 24 thus no electrical voltage is applied, released and about its axis of rotation 16 relative to the bearing element 14 rotatable. By applying the electrical voltage to the piezo stacks, the shaft is relative to the bearing element 14 fixed and clamped. In other words, gets to the piezo stacks 24 applied an electrical voltage, which is called energizing, so the frame 18 and the bearing cap 20 moved relative to each other (not away from each other), causing the shaft 12 clamped and fixed. If the Bestromen repealed, so this is a relative movement of the frame 18 to the bearing cap 20 causes, at which the frame 18 and the bearing cap 20 for example, due to elastic springback move away from each other relative to each other, resulting in the release of the shaft 12 accompanied.

The 2 and 3 show an alternative embodiment of the storage arrangement 10 according to 1 , Like that 2 and 3 it can be seen, is a one-piece bearing ring 26 provided over which the shaft 12 on the bearing element 14 is stored. The one-piece bearing ring 26 includes a first bearing part 28 and integral with the first bearing part 28 trained second bearing part 30 which has a slot 32 of the bearing ring 26 spaced apart from each other.

The bearing ring 26 has connecting flanges 34 on, over which he by means of flange bolts 36 on the frame 18 screwed on and held so.

In the slot 32 and thus between the first bearing part 28 and the second bearing part 30 is a piezo stack 24 arranged with piezo elements. The bearing parts 28 and 30 are by means of a clamping screw 22 over the piezo stack 24 clamped together, so the piezo stack 24 between the bearing parts 28 and 30 is clamped. By means of the clamping screw 22 are the bearing parts 28 and 30 clamped together, so the shaft 12 in the de-energized state of the piezo stack 24 between the bearing parts 28 and 30 is clamped and not relative to the bearing element 14 and relative to the bearing ring 26 around the axis of rotation 16 can turn.

Analogous to the storage arrangement 10 according to 1 The wave becomes portrayed 12 by energizing the piezo stack 24 released, as by applying the electrical voltage to the piezo stacks 24 the bearing parts 28 and 30 relative to each other are moved away from each other, so that the gap 32 enlarged and the clamping of the shaft 12 reduced or canceled. If the current supply is terminated, this will cause the bearing parts to move towards one another 28 and 30 for example due to elastic springback due to their tension by means of the clamping screw 22 causes, causing the shaft 12 clamped and relative to the bearing element 14 and the bearing ring 26 is fixed.

As with the storage arrangement 10 according to 1 is also in the storage arrangement 10 according to the 2 and 3 a reversal of this described principle of action possible, so by energizing the piezo stack 24 a Aufeinanderzubewegen the bearing part 28 and 30 and thus jamming of the shaft 12 is effected. By canceling the energization is a relative movement between the bearing parts 28 and 30 causes, through which the bearing parts 28 and 30 Move away from each other, what with the release of the wave 12 accompanied.

At the bearing ring 12 it is thus a brake flange, by means of which the shaft relative to the bearing element 14 can be fixed and released. How the particular 3 can be seen, have the connecting flanges 34 recesses 38 which allow at least substantially free mobility in the direction of opening and closing the brake. The co-rotation of the entire brake flange is prevented.

At this point it should be noted that a multiple division of the bearing is also possible, in which the bearing is therefore divided into more than two parts. Advantageously, surfaces of the bearing, on which the shaft 12 is stored, such that the surfaces a deceleration and the clamping of the shaft 12 can withstand wear over a long service life. Advantageously, the clamping screws are 22 designed such that they frequent relative movements between the frame 18 and the bearing cap 20 or between the bearing parts 28 and 30 can endure at least essentially harmless. The clamping of the shaft can also be used in addition or alternatively, an axial movement of the shaft 12 relative to the bearing element 14 to avoid. This means that by clamping the shaft between the frame 18 and the bearing cap 20 or between the bearing parts 28 and 30 not just a rotation of the shaft 12 around its axis of rotation 16 relative to the bearing element 14 but also an axial movement of the shaft 12 along its axis of rotation 16 can be prevented.

Instead of the Piezo Stacks 24 are also other actuators such as electromagnetically actuated actuators used.

The 4 shows an alternative embodiment of the storage arrangement 10 according to the 1 to 3 , It's a piezo stack 24 and a reinforcing element 40 provided over which the frame 18 and the bearing cap 20 by means of the clamping screws 22 clamped together. In this embodiment of the storage arrangement 10 The bearing is through the clamping screws 22 brought into its usual form. By energizing the piezo stack, the bearing is additionally braced, so that the bearing clearance is zero and a braking effect is achieved. This means that by energizing the piezo stack (applying the electrical voltage) the shaft 12 on the bearing element 14 is fixed, so that the shaft 12 not about its axis of rotation 16 relative to the bearing element 14 turn and also can not move relative to this axially.

The reinforcing element 40 , which is formed, for example at least substantially steel, passes one of the piezo stack 24 acting force targeted to the camp.

In the storage arrangements 10 according to the 1 to 4 It is also possible, individual, the respective clamping screws 22 assigned to use piezo stacks, to which respective screw heads of the clamping screws 22 are supported. As a result, by energizing and canceling the energization a respective change in length of the respective clamping screw 22 causes corresponding relative movements between the frame 18 and the bearing cap 20 or between the bearing parts 28 and 30 for clamping or releasing the shaft 12 can be effected.

The 5 shows an adjusting device 42 for a reciprocating internal combustion engine, by means of which compression ratios of the reciprocating internal combustion engine are independently adjustable variably. The reciprocating internal combustion engine, for example, has four cylinders, each having a variably settable compression ratio. This means that each individual compression ratio of the respective cylinders can be adjusted variably and independently of the respective other compression ratios of the other cylinders. This means that the compression ratios are individually adjustable or adjustable in terms of cylinder and can be adapted to thermodynamic requirements of the corresponding cylinder. As a result, for example, a first of the cylinders can be operated with a first compression ratio which differs from a second compression ratio of a second one of the cylinders.

To illustrate the cylinder-individual adjustability or adjustability of the compression ratios, the adjusting device comprises 42 a control shaft 44 , which are four partial waves 46 . 48 . 50 and 52 includes. The partial wave 46 is a first of the Cylinder allocated during the partial wave 48 associated with a second of the cylinders. Accordingly, the partial wave 50 assigned to a third of the cylinder, while the part shaft 52 associated with the fourth cylinder of the reciprocating internal combustion engine.

The partial waves 46 . 48 . 50 and 52 are here about respective axes of rotation 54 relative to a crankcase 56 the reciprocating internal combustion engine rotatably mounted on the crankcase 56 stored. The crankcase 56 includes bearing caps 58 . 60 . 62 . 64 and 66 , through which in cooperation with corresponding housing parts of the crankcase 56 a warehouse lane 68 is formed, on which the actuating shaft 44 is stored. Again 5 it can be seen, are the axes of rotation 54 while arranged coaxially with each other.

It should be noted at this point that it is easily possible to use the 5 shown adjusting device 42 apply analogously to reciprocating internal combustion engines, which have one of four different numbers of cylinders. The number of partial waves corresponds 46 . 48 . 50 and 52 with the number of cylinders. In other words, the adjusting device comprises 42 at least as many partial waves 46 . 48 . 50 and 52 as the reciprocating internal combustion engine cylinder comprises.

The bearing caps 58 . 60 . 62 . 64 and 66 are for example by a respective bearing cap as the bearing cap 20 the storage arrangement 10 according to the 1 to 4 educated. Here are the bearing caps 58 . 60 . 62 . 64 and 66 for example by means of clamping screws 22 with the housing parts of the crankcase 56 for the training of the camp gate 68 connected so that the housing parts of the crankcase 56 for example, analogous to the frame 18 the storage arrangement 10 according to the 1 to 4 given are.

The bearing caps 60 . 62 . 64 and 66 are doing so with at least one respective piezo stack 24 provided by means of which a respective relative movement of the corresponding bearing cap 60 . 62 . 64 and 66 relative to the associated housing part of the crankcase 56 analogous to the piezo stacks 24 the storage arrangement 10 according to the 1 to 4 is feasible. This allows the partial waves 46 . 48 . 50 and 52 individually and independently of the other sub-waves 46 . 48 . 50 and 52 clamped and thus fixed or released. This is the adjusting device 42 the basis of the 1 to 4 described rapid, zero backlash and compact clamping brake realized so that each set, cylinder-specific compression ratio can be maintained at least substantially to a constant value over a certain period of time away. Because each of the partial waves 46 . 48 . 50 and 52 at least a separate piezo stack 24 is assigned and thus each of the partial waves 46 . 48 . 50 and 52 can be individually released or fixed, thus adjustment or adjustment of the compression ratio can be made individually for each of the cylinders of the reciprocating internal combustion engine.

The partial waves 46 . 48 and 50 each have a bearing receiver 70 . 72 and 74 on, in which the respective following partial wave 48 . 50 and 52 partially recorded. This means that thus the partial waves 46 . 48 50 and 52 at least partially mutually supported, what the space requirement, the weight, the number of parts and the cost of the actuator 42 keeps low. On the one hand, mutually supported parts 46 . 48 . 50 and 52 on the other hand are supported by the clamping brake, by means of which the partial waves 48 . 50 . 52 and 54 relative to the bearing caps 58 . 60 . 62 and 64 and can be fixed or released to the corresponding housing parts. The bearing cap 58 is not with a piezo stack 24 provided because the piezo stack 24 of the bearing cap 60 to the partial wave 46 corresponds and this is sufficient to the partial wave 46 relative to the bearing caps 58 and 60 and to the corresponding housing parts of the crankcase 56 to fix.

The 6 and 7 show respective diagrams 76 . 78 and 80 , on the basis of which a method for cylinder-specific adjustment or adjustment of the compression ratios of the reciprocating internal combustion engine according to 5 is illustrated. On the abscissa 82 the diagrams 76 . 78 and 80 is the crank angle of a crankshaft of the reciprocating internal combustion engine in degrees crank angle according to a directional arrow 84 applied in ascending order. The crankshaft is indirectly coupled with the piston received in the cylinders and serves to convert the translational movements of the pistons in the cylinders relative to these in a rotational movement of the crankshaft.

On the ordinate 85 of the diagram 76 is the angle of rotation of the control shaft 44 or one of the partial waves 46 . 48 . 50 or 52 according to a directional arrow 86 plotted, which represents the rotation angle of all partial waves 46 . 48 . 50 and 52 can be viewed. In the diagram 76 is a course 88 entered. Based on the course 88 it can be seen that the control shaft 44 or the corresponding partial wave 46 . 48 . 50 or 52 above the rising crank angle about its axis of rotation 54 is to be rotated, so as to shift the associated piston in the cylinder relative to this and so adjust the corresponding compression ratio of the corresponding cylinder. Like the course 88 it can also be seen, takes place the Twist the corresponding part shaft 46 . 48 . 50 or 52 around its associated axis of rotation 54 gradually. This results from the fact that the associated piezo stack 24 and according to the realized by this clamping brake alternately the control shaft 44 or the corresponding partial wave 46 . 48 . 50 or 52 releases and fixes. This is based on a history 90 in the diagram 78 to recognize. On the ordinate 92 of the diagram 78 with B is a braking state of the associated piezo stack 24 while with F a release state of the piezo stack 24 is designated.

Is the piezo stack located? 24 and thus the clamping brake realized by this in the release state F, so can the control shaft 44 or the associated partial wave 46 . 48 . 50 or 52 around its axis of rotation 54 rotate. Is the piezo stack located? 24 and thus realized by this clamping brake in the braking state B, so is the control shaft 44 or the associated partial wave 46 . 48 . 50 . 52 between the corresponding bearing cap 58 . 60 . 62 . 64 or 66 and the associated housing part of the dome housing 56 clamped and thus fixed, so they are not around their axis of rotation 54 can turn.

The rotation of the control shaft 44 or the partial wave 46 . 48 . 50 or 52 around its associated axis of rotation 54 takes place at least substantially passively taking advantage of forces and / or torques resulting from combustion processes in the associated cylinder and which starting from this cylinder via the piston on the control shaft 44 or the corresponding partial wave 46 . 48 . 50 or 52 Act. Is the piezo stack located? 24 in the release state F, these forces and / or torques acting over a certain period of time or over a certain degree of crank angle of the crankshaft can cause the partial shaft 46 . 48 . 50 and 52 twist. An active application and expenditure of restoring forces and / or torques, for example by an active actuator for setting or adjusting a compression ratio is not provided and not needed. This keeps the energy consumption of the adjusting device 42 low, so that the associated reciprocating internal combustion engine can be operated with low fuel consumption and low CO ₂ emissions.

In the diagram 80 is a course 94 registered, which one on the control shaft 44 or the corresponding partial wave 46 . 48 . 50 and or 52 acting torque characterized. On the ordinate 96 In this case, the values of the torque are plotted, with the ordinate 96 is divided by the value zero for the torque in a positive range P and in a negative range N. From this it can be seen that the torque is an alternating torque which can be positive (positive range P) and negative (negative range N) and correspondingly to the control shaft 44 or the associated partial wave 46 . 48 . 50 and 52 acts. This means that on the control shaft 44 or the partial waves 46 . 48 . 50 and 52 During the operation of the reciprocating internal combustion engine change moments act, which make it possible to realize the compression ratios purely and by a temporally at least substantially precisely defined braking intervention or by the braking interventions.

For example, causes the torque in the positive region P, a rotation of the actuating shaft 44 or the corresponding partial wave 46 . 48 . 50 or 52 in a first direction of rotation, which is accompanied by a desired adjustment or adjustment of the associated compression ratio, and the positive torque is currently acting on the control shaft 44 or the partial wave 46 . 48 . 50 or 52 , then the clamping brake is released, so that the positive torque of the control shaft 44 or the partial wave 46 . 48 . 50 or 52 desired twisted. In contrast, a rotation of the actuating shaft 44 or the partial wave 46 . 48 . 50 or 52 in a second, the first rotational direction opposite direction of rotation desired, but acts the positive torque (which is a movement of the actuating shaft 44 or the partial wave 46 . 48 . 50 or 52 would cause in the first direction of rotation), the clamping brake is closed, so that the actuating shaft 44 or the partial wave 46 . 48 . 50 or 52 is fixed and can not turn. The torque then changes to the negative (in the negative range N) and thus causes the rotation of the actuating shaft 44 or the partial wave 46 . 48 . 50 or 52 in the desired, second direction of movement, so is the control shaft 44 or the partial wave 46 . 48 . 50 or 52 released (enable state F), so that the negative torque is the actuating shaft 44 or the partial wave 46 . 48 . 50 or 52 desirably rotates in the second direction of rotation and so that the compression ratio can be set as desired.

The adjusting device 42 thus comprises passive actuators, which are designed as brake devices in the form of the clamping brake or the clamping brakes. D. h., Is that an actual job energy for adjusting or adjusting the compression ratios is not actively spend and rather at least substantially directly from the combustion chambers or a crank mechanism with the piston and the crankshaft is removed. There is only one energy, especially electric power, to power the piezo stacks 24 needed with the electrical voltage. However, this energy is particularly low.

The piezo stacks 24 are also advantageous in that they only low inertias have and thus very quickly between the respective release states F and the respective braking conditions B are switchable. Thus, the compression ratios can be adjusted in a short time and adjusted as needed.

The 6 shows, as described, a rotation of the actuating shaft 44 or the partial waves 46 . 48 . 50 and 52 or one of the partial waves 46 . 48 . 50 and 52 independent of the other partial waves 46 . 48 . 50 and 52 in one, for example the first, direction of rotation. The 7 shows a rotation of the control shaft 44 or the partial waves 46 . 48 . 50 and 52 or one of the partial waves 46 . 48 . 50 and 52 first in the first and then subsequently in the first direction of rotation opposite second direction of rotation.

The 8th shows a reciprocating internal combustion engine 98 which has a plurality of, for example four, combustion chambers in the form of cylinders. The cylinders have a respective compression ratio, which is jointly, ie simultaneously and thus dependent on each other variably adjustable.

This includes the reciprocating internal combustion engine 98 an adjusting device 42 , Which are to the effect of the actuator 42 according to 5 differentiates that the adjusting shaft 44 is integrally formed. The control shaft 44 is about the axis of rotation 54 relative to a crankcase 56 the reciprocating internal combustion engine 98 rotatably mounted on this. For storing the control shaft 44 is the storage arrangement 10 according to 1 provided, with the frame 18 through the crankcase 56 is formed.

The one-piece control shaft 44 is formed as an eccentric shaft, which comprises a plurality of eccentric pins. The number of eccentric pins corresponds to the number of cylinders of the reciprocating internal combustion engine 98 , By turning the control shaft 44 around its axis of rotation 54 relative to the crankcase 56 the compression ratios of the cylinders are adjusted and adjusted together, whereby the compression ratios of thermodynamic requirements of the reciprocating internal combustion engine 98 can be adjusted. The control shaft 44 is the wave 12 the storage arrangement according to 1 or vice versa.

At the eccentric pin of the control shaft 44 each Nebenpleuel are rotatably mounted relative to the respective eccentric pin. On the other hand, the auxiliary connecting rods mounted on the eccentric pin are on the other hand articulatedly coupled to a respective transverse lever. The transverse levers in turn are at respective crank pin of a crankshaft of the reciprocating internal combustion engine 98 rotatably mounted relative to the pin. On the other hand, the cross levers articulated on the one hand with the secondary connecting rods are on the other hand articulatedly coupled to respective connecting rods of a crank drive, the connecting rods in turn being articulatedly coupled to respective pistons. The pistons are translationally received relative to the cylinders in the respective cylinders.

The crank mechanism also includes one in the 8th not shown crankshaft of the reciprocating internal combustion engine 98 wherein the crankshaft has a plurality of crank pins on which the transverse levers are rotatably mounted relative to the crank pin. Thereby, the translational movements of the pistons in the cylinders can be converted relative to these in a rotational movement of the crankshaft.

A rotation of the control shaft 44 (Wave 12 ) about the axis of rotation 54 (Axis of rotation 16 ) causes the transverse levers to rotate relative to the crankpins, which in turn causes a displacement of the pistons in the cylinders relative thereto. Thus, the compression ratios of the cylinder can be variably adjusted.

The twisting of the crankshaft 44 around the axis of rotation 54 takes place exclusively passive taking advantage of forces and / or torques, the forth from the cylinders forth on the piston and thus from the crank mechanism forth on the control shaft 44 Act. It is not intended, the control shaft 44 active, for example by means of an electric motor or the like actuator to the axis of rotation 54 to turn.

To illustrate this passive rotation of the control shaft 44 and thus this passive adjustment of the compression ratios is the result of the storage arrangement 10 formed clamping brake then opened when the of the cylinders on the control shaft 44 acting forces and / or torques a rotation of the actuating shaft 44 around its axis of rotation 54 would cause or effect in a desired first direction of movement. The clamping brake is kept closed or closed, when the forth of the cylinders forth on the control shaft 44 acting forces and / or torques a rotation of the control shaft 44 would cause or cause in a second, opposite to the first direction of rotation. In other words, the clamping brake is opened as needed only when the torques and / or the forces from the cylinders a desired movement of the actuating shaft 44 actually effect. Thus, by means of the clamping brake a demand-driven movement of the actuating shaft 44 causes and sets the compression ratio precisely and with a very low energy consumption or adjusted.

The 9 shows the reciprocating internal combustion engine 98 according to 8th , where the control shaft 44 by means of the storage arrangement 10 according to the 2 and 3 on the crankcase 56 is stored. Incidentally, this applies to the reciprocating internal combustion engine 98 according to 8th described on the reciprocating internal combustion engine 98 according to 9 analogous to.

LIST OF REFERENCE NUMBERS

10

bearing assembly

12

wave

14

bearing element

16

axis of rotation

18

frame

20

bearing cap

22

clamping screw

24

Piezo stack

26

bearing ring

28

First bearing part

30

Second bearing part

32

slot

34

connecting flange

36

Flange

38

recess

40

reinforcing element

42

setting device

44

actuating shaft

46

partial wave

48

partial wave

50

partial wave

52

partial wave

54

axis of rotation

56

crankcase

58

bearing cap

60

Location cover

62

bearing cap

64

bearing cap

66

bearing cap

68

Lagergasse

70

bearing seat

72

bearing seat

74

bearing seat

76

diagram

78

diagram

80

diagram

82

abscissa

84

arrow

85

ordinate

86

arrow

88

course

90

course

92

ordinate

94

course

96

ordinate

B

braking state

F

enable state

N

negative area

P

positive area

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 19627145 C2 [0002]

Claims (6)

Method for operating an internal combustion engine ( 98 ), in particular a reciprocating internal combustion engine ( 98 ), with at least one variably adjustable compression ratio, in which, for setting the compression ratio, a movement of at least one transmission element ( 12 . 44 . 46 . 48 . 50 . 52 ), via which the compression ratio is adjustable, in a first direction of movement and / or in a second, the first direction of movement opposite direction of movement by means of at least one actuator ( 24 ), characterized by the step: - switching the as a braking device ( 24 ) formed actuator ( 24 ) for effecting the movement of the transmission element ( 12 . 44 . 46 . 48 . 50 . 52 ) in the first or the second direction of movement of a movement preventing and the compression ratio at least substantially holding braking state in a movement enabling release state when a force and / or torque at least indirectly on the transmission element ( 12 . 44 . 46 . 48 . 50 . 52 ), which causes a movement of the transmission element ( 12 . 44 . 46 . 48 . 50 . 52 ) in the first or second direction of movement for adjusting the compression ratio. A method according to claim 1, characterized in that on the transmission element ( 12 . 44 . 46 . 48 . 50 . 52 ) acting force and / or the torque is detected by means of at least one detection device. Method according to one of claims 1 or 2, characterized in that the braking device ( 24 ) is switched a plurality of times between the braking state and the release state during a period of time during which the force and / or torque causing the movement in the first or second direction of movement acts. Method according to one of the preceding claims, characterized in that for braking the transmission element ( 12 . 44 . 46 . 48 . 50 . 52 ) the braking device ( 24 ) at least temporarily after a movement of the transmission element ( 12 . 44 . 46 . 48 . 50 . 52 ) is maintained in the first direction of movement in the release state when the force and / or the torque counteracts the movement in the first direction of movement after effecting the movement in the first direction of movement. Method according to one of the preceding claims, characterized in that the braking device ( 24 ) is switched from the release state to the brake state only when the speed of the transmission element ( 12 . 44 . 46 . 48 . 50 . 52 ) in one of the directions of movement falls below a predefinable threshold value. Adjusting device ( 42 ) for variably setting at least one compression ratio of an internal combustion engine ( 98 ), in particular a reciprocating internal combustion engine ( 98 ), with at least one actuator ( 24 ), by means of which, for variably setting the compression ratio, a movement of at least one transmission element ( 12 . 44 . 46 . 48 . 50 . 52 ), via which the compression ratio is adjustable, the adjusting device ( 42 ) in a first direction of movement and / or in a second, the first direction of movement opposite direction of movement is effected, characterized in that as a braking device ( 24 ) trained actuator ( 24 ) for effecting the movement of the transmission element ( 12 . 44 . 46 . 48 . 50 . 52 ) in the first or the second direction of movement of a movement preventing and the compression ratio at least substantially holding braking state in a movement enabling release state is switchable when a force and / or torque at least indirectly on the transmission element ( 12 . 44 . 46 . 48 . 50 . 52 ), which causes a movement of the transmission element ( 12 . 44 . 46 . 48 . 50 . 52 ) in the first or second direction of movement for adjusting the compression ratio.

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