DE102008050827A1 - Adjusting device for adjusting compression ratios of Otto engine crankshaft, has actuator displacing locking mechanism into free running position in fail-safe position to allow crankshaft to automatically take minimum compression position - Google Patents

Abstract

The device has a locking mechanism (11) i.e. free-wheel, preventing automatic adjustment of a crankshaft (9) in a direction of a minimum compression position and/or a maximum compression position in a locking position. An isolating actuator (13) e.g. electrical isolating motor, displaces the locking mechanism into a free running position in a fail-safe position for allowing the crankshaft to automatically take the minimum compression position without activating an adjusting motor (1). A clamping body is arranged at a periphery of a cage. An independent claim is also included for a method for controlling an adjusting device for a crankshaft of an internal combustion engine.

Description

Field of the invention

The The invention relates to an adjusting device for a crankshaft an internal combustion engine according to the preamble of claim 1 and a method for their control.

The Field of the invention is particularly, but not exclusively, on devices for adjusting the compression ratio of Piston internal combustion engines.

For the energy-efficient operation of a modern internal combustion engine In particular, a gasoline engine is a variable and customizable compression desirable. A firm compression is generally through the Knock limit at full load operation (eg compression ratio ε = 9) limited. In part load operation, however, would be an increase the compression ratio to a reduction of the specific Fuel consumption lead (eg compression ratio ε = 14). The possibilities to realize a variable Compression for reciprocating internal combustion engines are numerous described in the prior art.

From the DE 30 04 402 A1 is a crank mechanism of a reciprocating internal combustion engine with variable compression ratio known whose crankshaft is mounted in the crankcase in height adjustable. The crankshaft is mounted in eccentric rings, which are connected to gears, wherein each gear engages in each case a pinion, which is arranged on a parallel to the crankshaft extending actuating shaft which is in communication with an actuator.

From the DE 36 01 528 A1 Furthermore, an arrangement for the variable compression of a piston internal combustion engine of the aforementioned type is known in which the crankshaft bearing bearing eccentric rings are connected to a concentric with the eccentric aligned and extending over the entire length of the engine block cylinder shell. The cylinder part shell is provided on its outer side with a toothed segment, in which engages a connected to an actuator, extending transversely to the crankshaft adjusting screw. This arrangement has the advantage that it is self-locking ie an unintentional adjustment is not possible. However, it is disadvantageous that the moments which become effective in operation as a result of the eccentricity of the crankshaft axis relative to the bearing axis of the eccentric rings can only be absorbed via the adjusting worm, which leads to rapid wear.

In the DE 36 44 721 A1 Another arrangement for variable compression of a reciprocating internal combustion engine is disclosed in which each eccentric ring is connected to a laterally projecting lever which carries a sliding block at its free end. Laterally parallel to the crankshaft, a control shaft is mounted, which is provided with an actuator and fork-shaped claws, each comprising the sliding block of an eccentric ring. Here, the disadvantage in turn is that it comes to a considerable stress due to the acting in operation on the eccentric pulsie-generating moments, which is associated with heavy wear in the sliding blocks.

From the US 2002/0043229 A1 an arrangement for variable compression of a reciprocating internal combustion engine is known, wherein the eccentric rings are each provided with an actuating arm having at its free end a toothed element which engages with a pinion, which is mounted with a motor shaft in the side and parallel to the crankshaft shaft connected is. The control shaft is in turn connected to an actuator. To avoid the backlash between pinion and toothed segment, which is due to the forces acting on the eccentric rings in operation torques, the pinions are formed by two pinions, of which the first pinion is fixedly connected to the actuating shaft and the second pinion rotatable relative to the first pinion and is arranged resiliently clamped. However, the tension of the spring is associated with energy losses, which is disadvantageous for this arrangement DE 297 19 343 U1 an arrangement for variable compression of a reciprocating internal combustion engine is known, in which the bearing of the crankshaft is arranged in eccentric rings, which in turn are pivotally mounted in split, each with a bearing cap bearing bearings in the engine block and which are each provided with a pivoting lever. The bearing caps each have a window through which a respective pivoting lever of the associated eccentric ring is guided and connected to a connecting rod connecting the free ends of all pivoting levers. The coupling rod has at least one toothed segment, which is in communication with a pinion of an actuator. An electric motor deflects the eccentric rings via a lever via its output shaft and an intermediate shaft. The actuator is designed to be self-locking, so that the operation of the piston in the expansion or compression stroke due to the eccentricity between the crankshaft axis and the pivot axis on the eccentric rings acting torques are absorbed and the set via the actuator each set compression ratio is reliably maintained.

The above acknowledged writings focus on the presentation of an adjustment Direction for variable crankshaft adjustment or variable compression of a piston internal combustion engine according to the basic principle of an eccentric bearing of a crankshaft. In principle, the total ratio necessary for the operation of the adjusting device can be divided into one or more parts which act within an adjusting housing or have one or more uniformly or nonuniformly acting parts outside the adjusting housing.

The font "Variable compression ratio in the internal combustion engine by eccentric crankshaft displacement", Shaker Verlag, Aachen 2001, p. 124 shows an actuator which includes a gear and an electric motor. In this context, it is mentioned that for safety reasons, a parking brake must be provided for the time without adjustment, as far as no self-locking exists.

at an adjusting device for variable compression of a reciprocating internal combustion engine according to the acknowledged writings disclosed type acts due to the superposition of mass and gas forces on the load side a force or torque on the electric motor, which forms the adjustment drive (actuator). This causes the adjustment drive to be the least Compression corresponding position is driven as soon as the motor current below the value corresponding to the equilibrium of forces sinks. In the case of the de-energized state of the electric motor is the actuator quickly driven into its final position and remains then there. To hold each adjustment position of the crankshaft above the position corresponding to the value of least compression the electric motor is energized. These holding currents can application dependent z. B. between 20 A and 100 A. This leads to high sustained power loss, as the Position of lowest compression is approached only very rarely. This high power loss leads on the one hand to an increased Load on the electrical system and thus high fuel consumption. On the other hand, the high power loss leads to a fast Heating in particular of the electric motor and the power electronic Components that wear out quickly as a result.

Starting from the DE 297 19 343 U1 The object of the invention is to provide an improved adjusting device for the crankshaft of an internal combustion engine and to provide a suitable driving method.

The This object is achieved by an adjustment for the crankshaft of an internal combustion engine according to the attached claim 1 and by a method for their Control according to claim 15 solved.

The Adjustment device according to the invention is for used the crankshaft of internal combustion engines, which in eccentric rings is stored. Preferably, the eccentric rings are in turn in support bearings mounted pivotably in the engine block and each with a pivot lever provided, wherein the free ends of all pivoting levers with a coupling rod are connected, which has at least one toothed segment, the connected to a pinion which is connected to an adjusting shaft an electric motor is arranged. By adjusting the can in this way variable compression ratios be set in the internal combustion engine.

The Adjustment device according to the invention but can also in other adjusting devices for changing the Be used compression ratio, the described Adjusting drive require.

Of Furthermore, the adjusting device according to the invention comprises a locking mechanism having a locking and has a freewheeling position. In the locking position is a automatic adjustment of the crankshaft at least in the direction Minimal compaction position prevented. This is also a crankshaft initiated Adjustment of the adjusting prevents. Here can be different positive and / or positive-locking locking mechanisms come into question, wherein the adjusting device in addition is provided with a release actuator, in the fail-safe state (ie if z. B. in case of failure of the adjustment one for all Load cases occupied reliable position of the crankshaft must) the Verriegelungsmecha mechanism in the freewheeling position adjusted to the crankshaft taking the minimum compaction position to enable. In the fail-safe state, the crankshaft thus, without activating the adjusting shaft drive, brought into the minimum compacting position, due to the impressed by the piston forces.

In general, the adjusting device according to the invention should, under normal operating conditions, permit the adjustment of the compression by displacement of the crankshaft, as has hitherto been customary. For this purpose, an independent movement of the crankshaft or coupled to the adjusting shaft in the direction of minimum compression position must be prevented by the locking mechanism is activated when the crankshaft has assumed the desired position in the respective operating state. The adjustment can then be turned off. At the same time, the active adjustment of the adjusting shaft or the coupled crankshaft should remain possible in order to adapt to the load case. It is also crucial that in case of failure, a fail-safe state is turned on can be taken, even if the adjustment is no longer functional or for other reasons, a load-dependent adjustment of the compression is no longer possible. This allows the unlocking actuator, which solves the locking mechanism when needed and thus allows the independent transition to the minimum compression position.

Of the Locking mechanism can be at different points of the adjustment be arranged, for example, during storage of the crankshaft in Einstelllagern, which are designed as Exzenterringe, at one Any position from the eccentric rings to a Output shaft of an electric motor or a similar adjustment. It takes the necessary to lock force or the moment with decreasing translation so in the direction of the output shaft of the electric motor of the adjustment down. The mechanical Load and thus also the required space for the adjustment also decrease in this direction. Therefore is an arrangement of the locking mechanism in or near the Adjustment or particularly preferably on the adjusting shaft. expedient is also an integration of the locking mechanism and the release actuator for the fail-safe state in the adjusting drive, which is a common Housing allows. In this embodiment is the functionality of the unit before its assembly Tested on the internal combustion engine and simplified assembly itself, because the unit can be easily attached to the adjusting shaft.

Naturally it is also possible the locking mechanism with the Activation actuator in a separate unit outside to place the adjusting drive. In such an embodiment the locking mechanism and the release actuator, for example attached to the output shaft of the engine or to the adjusting shaft.

Of the Unlocking actuator is preferably via its own energy connection supplied, which remains functional even if the Adjustment drive fails and the fail-safe state is approached got to. This includes hydraulically or pneumatically driven Unlocking actuators, as well as constructions in which the unlocking actuator, for example is activated by spring force when the other power supply fails.

In a preferred embodiment of the invention Adjustment device is the unlocking actuator an electromagnet, wherein the locking mechanism is designed as a clamping freewheel, which for locking the adjusting shaft in a direction of rotation in the locking position and to release the adjusting shaft in both directions of rotation in the freewheeling position is adjustable. In Locking position corresponds to the released direction of rotation of the adjusting shaft an adjustment of the crankshaft in the direction of maximum compression position, while by locking the other direction of rotation a automatic movement of the crankshaft in the direction of minimal compaction position is prevented. For adjusting and holding the locking mechanism in the freewheeling position, the electromagnet with electric Electricity supplied. This triggers with the help of the established magnetic force a blocking element in the freewheel to release the locking mechanism. This is a rotation of the adjusting in both directions or an adjustment of the crankshaft, in particular in the direction Minimal compaction position and maximum compaction position allows. By the currentless holding the locking position is the adjustment according to the aforementioned embodiment energy-efficient. In case of failure of the electromagnet or in the case a simultaneous failure of the adjustment and the electromagnet the locking mechanism then remains in its current position. When the locking mechanism is in the locking position is located during the failure, becomes an automatic Ingestion of the minimum compression position of the crankshaft prevented.

With a reversal of the switching function of the electromagnet can this Disadvantage to be dealt with. If in a modified embodiment the unlocking actuator for adjusting the locking mechanism is not energized in the freewheeling position but when switching off the power supply goes into the fail-safe state, are the release of the two directions of rotation of the adjusting and thus an automatic intake of minimum compaction position by the crankshaft in case of failure of the adjustment also at Loss of electrical supply energy guaranteed. In this Case, the electromagnet must be supplied with electric current, to the locking mechanism in the locked position adjust and hold it. This is with the disadvantage connected, that for holding the locking position electrical Energy is consumed. However, because of the energy consumption the lower level of power consumption of the electromagnet negligible.

Of the Motor current of the adjustment drive is activated when the fail-safe state preferably lowered to zero to prevent damage.

In a further embodiment, the clamping freewheel locks the rotation of the adjusting shaft in both directions of rotation, while it releases both directions of rotation of the adjusting shaft in the freewheeling position. In case of failure of the adjustment and activation of the freewheel actuator, for example by turning on an electromagnet, so that an automatic assumption of the minimum compression position of the crankshaft is guaranteed, wherein after reaching the Mindestverdichtungsla ge the crankshaft, the power supply of the solenoid is turned off. Keeping the lock position without power reduces energy consumption in the fail-safe state.

at a further modified embodiment of the invention Adjustment device is the unlocking actuator preferably by the the adjusting shaft driving electric motor formed, with separate Power supply is provided during the locking mechanism is designed as a clamping freewheel. For adjusting and holding the locking mechanism in the locking position or to Locking the adjusting shaft either in the direction of minimum or maximum compression position the crankshaft is activated by the electric motor. Is advantageous it that the locking position of the locking mechanism is held passive, d. H. that for adjusting and holding the locking position the electric motor does not have to be activated. The electric motor can either with internal rotor or with external rotor be executed. However, in one execution with external rotor the development of a high moment of inertia disadvantageous.

In another embodiment of the invention Adjustment device is the locking mechanism as a brake educated. Preferably, the brake is an electric brake executed, although the use of a hydraulic or mechanical brake is also possible. The unlocking actuator may again be an electromagnet, the brake a first and a second brake element, which in the freewheeling position are separated by an air gap and in the locking position with their surfaces frictionally together issue. The first brake element is connected to the adjusting shaft, while the second brake element with a housing the adjusting drive is rotatably connected. At least one of these Brake elements is magnetizable and by the energizing the Electromagnet magnetic force generated between the freewheeling and locking position adjustable. Thus, the adjusting is in the locked position the electric brake locked in both directions, in particular thus becomes an automatic adjustment of the crankshaft prevented in the direction of minimum compaction position. Upon occurrence a fail-safe state is by adjusting the electrical Brake in the freewheeling position a free rotation of the adjusting shaft in both directions possible. This can be an automatic Adjustment of the crankshaft in the minimum compression position below the action of the piston side torque take place.

to The braking effect can be increased in the locking position the brake adjacent surfaces structured be executed or have brake torque increasing recesses. Overall, the brake as a multi-disc brake with several consecutive switched brake elements are executed, which in the locking position engage simultaneously.

In a further modified embodiment of the Adjustment device according to the invention is the Locking mechanism designed as a wrap spring. The Wrap is wrapped around one with a housing the adjusting drive associated housing extension and a arranged rotationally fixed with the adjusting shaft connected paragraph. One The end of the wrap is bent up and protrudes into a groove Shift sleeve, which rotatable with respect to a housing the adjusting drive is mounted and provided with a shift finger is. The wrap is based on the shift finger by the unlocking actuator adjustable between the unlocking and the locking position. In the locking position is preferably the direction of rotation of the Adjusting shaft locks, which the automatic intake the minimum compression position corresponds to the crankshaft. In however, the free-running position of the wrap spring becomes the rotation the adjusting shaft released in both directions. So that can the locking mechanism in case of failure of the adjustment be adjusted to the freewheeling position, and the adjustment of Crankshaft in a minimum compression position is using the through allows the pistons of the engine generated moments.

Of the Adjustment of the adjusting device according to the invention is preferably with a brushless electric motor with Rare earth magnet rotor leads out. The electric motor is preferably constructed with internal rotor. Alternative embodiments, such as B. a hollow shaft design are also possible. Preferably the electric motor of the adjustment is only with the necessary Power electronics equipped while the controller in the engine control unit or separately in spatial Close to the power electronics is integrated. This remains the control before the resulting during operation of the electric motor Protected from heat loss.

preferred Embodiments of the invention Adjusting device are shown in the figures and will be below explained in more detail. Show it:

1 a side view of a first embodiment of an adjusting device according to the invention for a crankshaft of a combustion motors and a cross-sectional view of a locking mechanism used therein in the form of a clamping freewheel;

2 a side view of a second embodiment of the adjusting device and two sectional views of the locking mechanism;

3 a detailed view of a modified locking mechanism in cross section;

4 a simplified side view of another of the adjusting device with a magnetically activated brake as an unlocking actuator;

5 a side view of a fifth embodiment of the adjusting device and a cross section of a detail of the locking mechanism.

1 , Fig. A) shows a side view of a first embodiment of an adjusting device according to the invention for a crankshaft of an internal combustion engine. This embodiment can be understood as an active barrier with connectable freewheel. The adjusting device comprises an adjusting drive with an adjusting motor 01 with an output shaft 03 , The output shaft 03 is about a first gear stage 05 with an adjusting shaft 07 connected and acts on a crankshaft 09 an internal combustion engine. The gear stage 05 is z. B. designed as a planetary gear Wolfrom type. The output shaft 03 the adjusting motor 01 has a locking mechanism 11 and a freewheeling actuator disposed radially thereon 13 on which in a housing 15 the adjusting motor 01 are positioned. The freewheeling actuator is in this embodiment as an electromagnet 13 executed. Of course, the arrangement rotor and stator of the adjusting motor can be exchanged mutatis mutandis without the described basic functionality is lost. However, the disadvantage is then the higher moment of inertia in the arrangement of the rotor on a larger mass effective diameter (hollow shaft motor).

A detail view with a cross section of the locking mechanism 11 is in 1 , Fig. B). The locking mechanism 11 is designed as a clamping freewheel. The clamping freewheel comprises a rotationally fixed to the housing 15 the adjusting motor 01 connected outer ring 17 with recesses on the inner wall 19 and a rotationally fixed to the output shaft 03 connected cage 21 , At the periphery of the cage 21 are clamp bodies 23 with pressure springs for holding the clamp body 23 in the recesses 19 of the outer ring 17 arranged in a freewheeling position of the clamping freewheel. Furthermore, an outstanding shift finger 25 and return springs 24 available. The cage 21 the clamping freewheel is by the shift finger 25 arranged opposite and acting on this electromagnet 13 with respect to the outer ring 17 rotatable, taking in the cage 21 arranged clamping body 23 turn and be clamped. In an in 1 , Abb. B) shown first switching position, it comes to clamping the output shaft 03 if this in by a rotary arrow 26 clarified direction is turned - the locking position is occupied. Is by pressing the shift finger 25 a second shift position taken (not shown), the output shaft is freely rotatable in both directions - the freewheeling position is taken. In the second, the variable compression mechanism is adjustable in the direction of increasing or decreasing compression. The electromagnet 13 is energized to set this second switching state.

For maintaining a constant compression ratio, the shift finger 25 positioned in the first switching position. The load from the compression mechanism acts in this position in the direction of rotation 26 , The freewheel locks. The electromagnet 13 is preferably not energized to set this first switching state to minimize the electrical power consumption in the hold state. To initiate a compression ratio change is the shift finger 25 moved to the second switching position, the cage 21 taken and the pinch rollers 23 unlocked. This process can be supported by the fact that the adjusting motor 01 in the unlocking operation of the freewheeling favorable position (torque acting direction opposite to the arrow 26 ) is pre-energized before the energization, after reaching the second switching state, is set in the adjustment direction corresponding to the compression change.

In case of failure of the power supply of the adjusting motor 01 (Error case A), the mechanism adjusts due to the adjusting shaft 07 acting load automatically in the lower compression end position (minimum compression position) and remains there - the fail-safe state is taken. The minimum compression position is formed by a mechanical end stop (not shown), which can be arranged within the adjustment mechanism at any position between the eccentric bearing and the output shaft of the variable displacement motor. The shift finger 25 is positioned to take the fail-safe state in the second switching position, but can also be positioned in the first switching position after reaching the minimum compression position. The electromagnet 13 of the freewheel is no longer energized.

In case of failure of the power supply of the electromagnet 13 (Error B), the mechanism remains in its current Verdichtungspositi on at the time of power failure. This error case is therefore not intercepted when the Schaltdfinger 25 is in the first switching position. As error case C, a combination of error cases A and B is possible.

Of course, also a reversal of the switching function of the electromagnet 13 conceivable. Advantageously, the mechanism then moves in case of error B, ie in case of failure of the power supply of the electromagnet 13 (A return spring of the electromagnet thereby moves the shift finger 25 in the second switching position), by the on the adjusting shaft 03 acting load in the minimum compaction position and remains there (fail-safe state taken). The electric motor current is then lowered to avoid damage to the adjusting motor preferably to zero. The disadvantage in this case is that the electromagnet 13 must be energized for holding a set compression ratio. This leads to a permanent electrical power consumption of the electromagnet 13 which, however, can be accepted because of its low height.

2 , Fig. A) shows a three-dimensional view of a second embodiment of the adjustment device according to the invention for the crankshaft of an internal combustion engine, in which case the locking mechanism 11 in a storage unit 27 is integrated and the unlocking actuator 13 in the axial direction next to the storage unit 27 is arranged. The storage unit 27 and the unlock actuator 13 are together in the housing 15 the adjusting motor 01 positioned.

2 Fig. B) shows a detail view in cross section of the locking mechanism 11 , which is designed as a clamping roller freewheel. The clamping roller freewheel comprises an outer ring 29 with wedge angles incorporated on the inner wall 31 and a rotationally fixed to the output shaft 03 connected cage 33 with a cage collar 35 (Fig. C). The cage 33 contains arranged on its circumference clamping body 37 with pressure springs for holding the clamp body 37 in the wedge angles 31 of the outer ring 29 in a locking position of the clamping freewheel.

2 , Fig. C) are the release actuator 13 and the locking mechanism 11 in a detailed view in longitudinal section of the storage unit 27 refer to. The unlocking actuator 11 is opposite the cage collar 35 arranged and includes an electromagnet 39 with a pole surface 41 , Furthermore, one to the pole face 41 sliding anchor plate 43 as well as compression springs 45 available. To release the rotation of the cage 33 in both directions becomes the pole face 41 through the electromagnet 39 attracted, with the compression springs 45 be tense. A slowing down of the cage 33 over the cage collar 35 done by the anchor plate 43 , which by the biasing force of the springs 45 against the cage collar 35 is pressed. When braking the cage 33 the clamping freewheel is simultaneously adjusted to a locking position. The clamp body 37 , which are designed as pinch rollers, roll in the wedge angles 31 of the outer ring 29 the storage unit 27 on until the clamping condition is reached.

For adjusting and holding the clamping freewheel in freewheeling position of the electromagnet 39 energized and the anchor plate 43 against the pole surface 41 dressed. At the same time the output shaft 03 through the adjusting motor 01 rotated in the opposite direction to the wedge angles, causing the clamp body 37 be disconnected. In case of failure of the adjusting motor is an automatic adjustment of the crankshaft after adjusting the clamping freewheel in the freewheeling position 09 allowed in the minimum compaction position. After reaching the minimum compression position of the necessary to hold the freewheeling position of the clamping freewheel electromagnet 39 turned off. In the locking position of the clamping freewheel, however, is an electroless locking of a minimum compression position corresponding direction of rotation of the output shaft 03 the adjusting motor 01 or the adjusting shaft 07 locked.

Of course, a reversal of the switching function of the electromagnet is conceivable. The compression springs 45 then be on the other side of the anchor plate 43 arranged or replaced by tension springs. As a result, the positions are replaced without current / current. This can be taken in the case of failure of the adjustment motor, a position in the lower compression position, which is held due to the continuous unidirectional torque from the load on the mechanism. However, using this logic, it is not possible to intercept the failure of the failure of the solenoid (prior to a potential failure of the variable displacement motor).

3 shows a cross section of a modified locking mechanism, which, for example, in an adjustment according to 1 , Fig. A) can be used. The locking mechanism 11 is designed as a clamping freewheel, which is the rotation of the output shaft 03 the adjusting motor 01 or the adjusting shaft 07 the adjusting device locks passively in both directions of rotation and actively activates in one direction of rotation. A cage 47 of the clamping freewheel is connected to a second electric motor (unlocking motor), preferably via one of the adjusting motor 01 separate power supply is supplied. By the second electric motor, the clamping freewheel can be adjusted in a freewheeling position, which the free rotation of the output shaft 03 in one direction of rotation. in the Case of the unlocked mode of operation in the direction of the minimum compression position of the crankshaft 09 , a rotation is made in the direction of the maximum compression position of the crankshaft 09 blocked. In the case of the unlocked mode of operation in the direction of the maximum compression position of the crankshaft 09 the direction corresponding to a reduction in compression is blocked. In order to allow an operating current reduction for the engine in the hold case, an adjustment must first be made in the direction of increasing the compression.

When falling below the reverse current of the disconnecting motor locks the clamping freewheel. The reverse current generates an engine torque which approximately corresponds to the torque on the output shaft resulting from the average operating load. Should be based on a position of the adjusting shaft 07 , which is held in a locking position of the clamping freewheel, a corresponding change in the compression position of the adjusting shaft 07 be driven, it is a rapid increase in the operating current of the unlocking motor to a value (preferably significantly) above the reverse current, so that the clamping freewheel releases quickly and it does not come during the release phase due to the changing load torque to undefined release and locking operations that the life of Would lower clamping freewheel.

In case of error, the cage 47 initially released in the direction, which is an adjustment of the crankshaft 09 in the direction of minimum compaction position. When reaching the minimum compression position of the cage 47 optionally switched in the other direction. As a result, a persistence of the crankshaft is achieved in the minimum compression position, it may be suppressed noise that may result from a moment zero crossing of the load.

Advantage of this clamping freewheel is a current-free holding a compression position. Even with load moments at zero crossing, a position of the adjusting shaft corresponding to a specific compression can be achieved 07 be kept safe. A disadvantage is the need for an external release motor, which is able to apply a torque acting in both directions of rotation.

4 shows a fourth embodiment of the adjustment device according to the invention for the crankshaft of an internal combustion engine in a simplified longitudinal section. The locking mechanism of the adjusting device is here by a z. B. electromagnetically actuated brake.

A housing 49 the brake is with the housing 15 the adjusting motor 01 rotatably connected. The unlocking actuator 13 is as a magnetic coil 51 executed and with the housing 49 rotatably connected. The magnetic coil 51 is opposite a brake disc 53 arranged, which in turn with a spring 55 about rivets 57 is connected, the spring 55 via parent connection 59 with the output shaft 03 the adjusting motor 01 positively connected. The connection of the brake disc 53 with the spring 55 allows axial movement of the brake disc 53 , In a freewheeling position of the electric brake are the brake disc 53 and the case 49 the brake separated by an air gap. By energizing the solenoid 51 , which is on the other side of the case 49 is attached, the brake disk 53 by the generated magnetic force to the housing 49 dressed. By friction between the brake disc 53 and the housing 49 the brake is a braking torque generated and the brake is moved to a locking position, which is a locking of the two directions of rotation of the output shaft 03 the adjusting motor 01 or the adjusting shaft 07 corresponds to the adjustment. When switching off the power supply of the solenoid 51 becomes the brake disc 53 by the biasing force of the spring 55 moved back and thus adjusted the brake in the freewheeling position. The brake disc 53 consists of magnetizable material. The housing 49 The brake also consists of a magnetically conductive material.

5 , Fig. A) shows a partially sectioned side view of a fifth embodiment of the adjusting device according to the invention for the crankshaft of an internal combustion engine. The locking mechanism 11 is here as a wrap 61 educated. The wrap 61 is entwining on one with the housing 15 the adjusting motor 01 connected housing extension 63 and a rotationally fixed with the adjusting shaft 07 linked paragraph 65 arranged. An end 67 the wrap spring 61 is bent up and protrudes into a groove 69 a switching sleeve 71 which is rotatable with respect to the housing 15 is stored and with a shift finger 73 is provided (Fig. b). The unlocking actuator 13 is designed as an electromagnet and in the radial direction above the shift sleeve 71 arranged.

The 5 , Fig. B) shows a cross section of the wrap spring 61 , The diameter of the housing extension 63 and the paragraph 65 on which the wrap spring 61 centered, is slightly larger than the inner diameter of the unstressed wrap spring 61 , This will be a basic tension between the wrap spring 61 and the housing extension 63 on the one hand and the paragraph 65 on the other hand ensured. When energizing the electromagnet is by means of the shift finger 73 the shift sleeve 71 rotated, causing the wrap spring 61 also rotates. Upon rotation of the shift sleeve 71 in the reverse direction, the wrap pulls 61 due to friction between its inside diameter and outside diameter of the housing extension 63 and paragraph 65 firmly; This is an adjustment of the wrap 61 in a locking position. When turning in the opposite direction, the wrap spring is relieved 61 , whereby the frictional engagement is canceled and the adjusting shaft 07 is freely rotatable. This will be the wrap 61 adjusted to a freewheeling position. Because of the sliding movement between the housing extension 63 or paragraph 65 and the wrap spring 61 In freewheeling position, a lubricating oil supply is useful to reduce possible wear and friction.

By activating the electromagnet, an adjustment and attitude of a locking position of the wrap occurs 61 , which is an adjustment of the adjusting shaft 03 in the direction of the minimum compression position of the crankshaft 09 in derogation. Also by the activation of the electromagnet is an adjustment of the wrap 61 in a release position possible, whereby the rotation of the adjusting 03 is released in both directions of rotation and the automatic adjustment of the crankshaft 09 in the direction of minimum compaction position is allowed.

01

adjusting

03

output shaft

05

gear stage

07

adjusting

09

crankshaft pulley

11

locking mechanism

13

Freischaltaktuator

15

casing

17

outer ring

19

recesses

21

Cage

23

clamping bodies

24

Return spring

25

shift finger

26

direction of rotation

27

storage unit

29

outer ring

31

wedge angle

33

Cage

35

cage Bund

37

clamping bodies

39

electromagnet

41

pole

43

anchor plate

45

compression spring

47

Cage

49

casing

51

solenoid

53

brake disc

55

feather

57

rivet

59

parent compound

61

wrap

63

Housing extension

65

paragraph

67

The End

69

groove

71

switching sleeve

73

shift finger

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• DE 3004402 A1 [0004]
• - DE 3601528 A1 [0005]
• - DE 3644721 A1 [0006]
• US 2002/0043229 A1 [0007]
• - DE 29719343 U1 [0007, 0011]

Cited non-patent literature

• - "Variable compression ratio in the internal combustion engine by eccentric crankshaft displacement", Shaker Verlag, Aachen 2001, p. 124 [0009]

Claims (18)

Adjustment device for a crankshaft ( 09 ) of an internal combustion engine which is mounted in adjusting bearings, which via an adjusting shaft ( 07 ) is adjustable to the position of the crankshaft ( 09 ) between a minimum compression position and a maximum compression position, comprising an adjusting shaft drive ( 01 ) and a positive and / or non-positive locking mechanism ( 11 ), which can assume a locking and a freewheeling position and in the locking position, an automatic adjustment of the crankshaft ( 09 ) in the direction of minimum compression position and / or maximum compression position, characterized in that a release actuator ( 13 ) is provided, which in a fail-safe state, the locking mechanism ( 11 ) in the freewheeling position to the crankshaft ( 09 ) to enable the automatic assumption of the minimum compaction position, without the adjustment shaft drive ( 01 ) to activate. Adjusting device according to claim 1, characterized in that the locking mechanism ( 11 ) is designed as a clamping freewheel, for locking the adjusting ( 07 ) in at least one direction of rotation in the locking position and to release the adjusting shaft ( 07 ) is switchable in both directions of rotation in the freewheeling position. Adjusting device according to claim 2, characterized in that the clamping freewheel comprises: - an outer ring ( 17 ) with incorporated recesses ( 19 ), - one with respect to the outer ring ( 17 ) rotatable cage ( 21 ), - on the circumference of the cage ( 21 ) arranged clamping body ( 23 ), which in the freewheeling position with pressure springs in the recesses ( 19 ), - one with the cage ( 21 ) and via the outer ring ( 17 ) outstanding shift fingers ( 25 ), which is used for switching between locking and freewheeling position of the release actuator ( 13 ) is pressed. Adjusting device according to claim 2 or 3, characterized in that the unlocking actuator ( 13 ) is designed as an electromagnet. Adjusting device according to claim 1, characterized in that the locking mechanism ( 11 ) is designed as a clamping freewheel, for locking the adjusting ( 07 ) in both directions of rotation in the locking position and to release the adjusting shaft ( 07 ) is switchable in both directions of rotation in the freewheeling position. Adjusting device according to claim 5, characterized in that the clamping freewheel in a storage unit ( 27 ) for the storage of the adjusting shaft ( 07 ) within a housing ( 15 ) of the adjusting drive ( 01 ) is integrated. Adjusting device according to claim 6, characterized in that the clamping freewheel comprises: - an outer ring ( 29 ) of the storage unit ( 27 ) with incorporated wedge angles ( 31 ), - a rotationally fixed with the adjusting shaft ( 07 ) associated cage ( 33 ) with a cage collar ( 35 ), - on the circumference of the cage ( 33 ) arranged clamping body ( 37 ) in the locking position with pressure springs in the wedge angles ( 31 ), wherein the release actuator relative to the cage collar ( 35 ) and an electromagnet ( 39 ) with a pole face ( 41 ) and an anchor plate ( 43 ) which is used to decelerate and release the cage ( 33 ) by the electromagnet ( 39 ) between the cage collar ( 35 ) and the pole face ( 41 ) is adjustable to the clamping freewheel by braking the cage ( 33 ) to bring into locking position. Adjusting device according to claim 1, characterized in that the locking mechanism ( 11 ) is designed as a clamping freewheel, for locking the adjusting ( 07 ) in both directions of rotation in the locking position and to release the adjusting shaft ( 07 ) is switchable in only one direction of rotation in the freewheeling position. Adjusting device according to claim 8, characterized that the unlocking actuator is an electric unlocking motor. Adjusting device according to claim 1, characterized in that the locking mechanism ( 11 ) is designed as a brake, which by the unlocking actuator ( 13 ) is adjustable between the freewheeling and the locking position, wherein the adjusting shaft ( 07 ) is locked in the locking position in both directions of rotation and is freely rotatable in the free-running position in both directions of rotation. Adjusting device according to claim 10, characterized that the brake is an electromagnetically operated brake with a first brake element and a second brake element, which are separated in the freewheeling position by an air gap and in the locking position with their surfaces frictionally abut each other. Adjusting device according to claim 11, characterized in that the first brake element rotationally fixed with the adjusting ( 07 ) and the second brake element rotatably with a housing ( 15 ) of the adjusting drive ( 01 ) Is connected, and that the unlocking actuator is an electromagnet, which generates a magnetic force when energized, which at the brake elements between the locking and the freewheeling position switches. Adjusting device according to claim 1, characterized in that the locking mechanism as a wrap ( 61 ) which is looped around at one with a housing ( 15 ) of the adjusting drive ( 01 ) housing extension ( 63 ) and a rotationally fixed with the adjusting shaft ( 07 ) ( 65 ) is arranged and one end in a shift sleeve ( 71 ) which is rotatable with respect to the housing ( 15 ) of the adjusting drive ( 01 ) is mounted and with a shift finger ( 73 ) for actuation by the release actuator ( 13 ) is provided. Adjusting device according to one of claims 1 to 13, characterized in that the adjusting bearing of the crankshaft ( 09 ) are formed by eccentric rings. Adjusting device according to one of claims 1 to 14, characterized in that the adjusting drive is an electric motor ( 01 ). Method for controlling an adjusting device for a crankshaft ( 09 ) of an internal combustion engine which is mounted in adjusting bearings, which via an adjusting shaft ( 07 ) are adjustable to the posi tion of the crankshaft ( 09 ) between a minimum compression position and a maximum compression position, wherein the adjustment device is a Verstellwellenantrieb ( 01 ), a locking mechanism ( 11 ) and a release actuator ( 13 ), and wherein the method is characterized by the following steps: detecting an error case which prevents the adjustment of the crankshaft between the minimum compression position and the maximum compression position; - Adjusting the locking mechanism ( 11 ) by the release actuator ( 13 ) from a locking position to a freewheeling position, in which the crankshaft ( 09 ) the automatic assumption of the minimum compression position is possible, without the adjustment shaft drive ( 01 ) to enter a fail-safe state. Method according to claim 16, characterized in that the locking mechanism ( 11 ) is left in the locked position until the error is detected. Method according to claim 15 or 16, characterized in that the locking mechanism ( 11 ) is reset to the locking position as soon as the fail-safe state of the crankshaft ( 09 ) was taken.