EP2935864A1

EP2935864A1 - Method and device for cranking an internal combustion engine

Info

Publication number: EP2935864A1
Application number: EP13791837.1A
Authority: EP
Inventors: Uwe Hinrichsen; Holger Lange; Henning Vogt
Original assignee: Volkswagen AG
Current assignee: Volkswagen AG
Priority date: 2012-12-20
Filing date: 2013-11-18
Publication date: 2015-10-28
Anticipated expiration: 2033-11-18
Also published as: DE102012025001A1; EP2935864B1; WO2014095195A1

Abstract

The invention relates to a device (1) and a method for cranking an internal combustion engine (2), wherein a crankshaft (3) is coupled in rotationally elastic fashion to a rotor (6) of a cranking motor (4), wherein, in a cranking process, the cranking motor (4) generates a cranking torque (AM) which is transmitted via the rotationally elastic coupling to the crankshaft (3), wherein, at a starting time of the cranking process, a negative or positive cranking torque (AM) is generated, wherein at least one change in sign of the cranking torque (AM) occurs during the cranking process, wherein a rotation of the crankshaft (3) is mechanically blocked before or at the starting time, wherein the rotation of the crankshaft (3) is enabled when or after the amount of energy stored in a rotary oscillation system reaches the maximum admissible amount of energy or an amount of energy required for cranking the internal combustion engine (2), wherein the rotary oscillation system is composed at least of the rotationally elastic coupling and the rotor (6) of the cranking motor (4).

Description

description

Method and device for starting an internal combustion engine

The invention relates to a method and a device for starting a

Internal combustion engine.

DE 10 2009 033 544 A1 discloses a method for starting a

Internal combustion engine of a motor vehicle, wherein the internal combustion engine exerts a drive torque in a preferred direction of the internal combustion engine to a crankshaft. A starter motor applies a starting torque to the crankshaft in a starting operation to achieve a minimum speed of the internal combustion engine, with a control unit controlling the starting torque. Here, the control unit in the starting process controls the starting torque time-dependent between a positive maximum starting torque and a negative minimum starting torque, with a positive starting torque in the direction and a negative starting torque against the preferred direction acts on the crankshaft.

The document also discloses a drive train arrangement in which the rotor of the

Electric machine trained starter motor torsionally elastic with the crankshaft of

Internal combustion engine is connected. Such an arrangement offers a number of advantages:

1 . The only rotating element of the starter motor, namely the rotor, a

Replace secondary mass of a dual-mass flywheel (DMF). This can result in a smaller moment of inertia for the overall mechanical system of crankshaft and starter, which in turn higher speed gradients

Speed changes allowed and thus a higher dynamics in the operation of the

Motor vehicle allows.

2. By suitable control of the starter motor rotational non-uniformities of the crankshaft can be fully or partially compensated. The arrangement thus allows active vibration damping or damping.

3. Since an electric rotor angle is usually required to control the starter motor, it can be converted into a mechanical rotor angle with little effort become. If a crankshaft angle is also known, a twist angle of an elastic coupling element, for example a torsion spring, can be determined from the difference between the crankshaft angle and the mechanical rotor angle. Depending on this angle of rotation, a currently transmitted torque between the rotor and the crankshaft can be determined. Thus, it is advantageous that no direct measurement of the torque is required.

4. If, as previously explained, the angle of rotation is known, it may depend on the

Angle of rotation an improved load change control done, in spite of the elastically behaved drive train fast and comfortable load changes can be compensated.

5. Depending on the angle of rotation can also be a control of the starting process done in such a way that a maximum amount of the rotation angle is not exceeded. As a result, e.g. a mechanical stress on end stops can be prevented. As a control variable for such a control, for example, the starting torque generated by the starter motor, the torque generated by the internal combustion engine or, in an automatic transmission, a clutch capacity can be used as a control variable.

6. In such a driveline arrangement, no wear of e.g. Belt on.

7. Further, no belt losses are generated in such an arrangement.

A disadvantage of such an arrangement, however, is that in particular for the cold start of the internal combustion engine high torques must be generated by the starter motor, especially when there is no torque ratio between the crankshaft and the rotor.

If the method disclosed in DE 10 2009 033 544 A1 is such

Applied driveline arrangement, so the crankshaft of the

Move internal combustion engine before reaching a maximum allowable angle of rotation of the torsionally elastic coupling element, i. resonate. Due to the especially at low temperatures high friction torque of the crankshaft, including with the

Crankshaft coupled other components, such as the piston and the camshaft, the arrangement energy is withdrawn, which should be desirable for starting available. In particular, it may come to an equilibrium, in which by the Anchor torque supplied energy of the discharged friction energy corresponds. In this case, starting the internal combustion engine would not be possible.

DE 10 2012 201 102 A1 discloses a vehicle with an internal combustion engine and an electric machine, which kinematically to start the internal combustion engine with the

Internal combustion engine can be coupled and which is kinematically decoupled during operation of the internal combustion engine of the internal combustion engine. The vehicle further comprises an energy recuperation and storage device, the energy recuperation and storage devices

Memory device during shutdown or during the expiration of the

Combustion engine is kinematically coupled to the internal combustion engine and at least part of the stored at the moment of switching off the engine in the engine kinetic energy stores and stores.

The technical problem is to provide a method and an apparatus for starting an internal combustion engine, the reliable start of the

Allow combustion engine, wherein requirements for a height of a maximum to be generated starting torque can be reduced.

The solution of the technical problem results from the objects with the features of claims 1 and 10. Further advantageous embodiments of the invention will become apparent from the dependent claims.

It is a basic idea of the invention to prevent a crankshaft of the internal combustion engine from rotating until such time as a crankshaft, a rotor of the starter motor and a mechanically coupling elastic coupling element form the same

Rotary oscillator reaches a state in which a stored in the rotary oscillator energy, which is composed of a potential energy of the torsionally elastic coupling element and a kinetic energy of the rotor of the starter motor, sufficient to start the internal combustion engine. In particular, the energy stored in the rotary oscillator is sufficient to produce e.g. by a static friction of the internal combustion engine required breakaway torque and compression and Gleitreibungsmomente the

Overcome internal combustion engine.

Proposed is a method for starting an internal combustion engine, wherein a crankshaft is rotationally elastically coupled to a rotor of an electric machine, for example via an elastic coupling element. In a starting process, the starter motor generates a Starting torque, which is transmitted via the torsionally flexible coupling to the crankshaft. The starter motor can be designed here as an electric machine.

At a starting time of the starting process, a negative or positive starting torque is generated. Here, a positive starting torque denotes a starting torque, which acts in a preferred direction of rotation of the crankshaft to the crankshaft. Correspondingly, a negative starting torque refers to a torque which acts counter to the preferred direction of rotation on the crankshaft. The preferred direction of rotation of the crankshaft corresponds to the direction of rotation of the crankshaft during operation of the internal combustion engine. Thus, the

Start the starting process either with a torque acting in the preferred direction of rotation or with a torque acting counter to the preferred direction of rotation. During the

Starting process is at least a change of sign of the starting torque. Time after the start time so the starter motor is controlled such that on a for

Starting time negative starting torque following a positive starting torque or to a generated at the start time positive starting torque following a negative starting torque is generated. Preferably, several sign changes of the starting torque occur during the starting process. This can also be described as a modulation of the starting torque. The modulation of the starting torque thus describes a control of the starting torque, wherein the starting torque between a positive starting torque and a negative

Starting moment changes. A sign change of the starting torque may e.g. time-dependent, so after a predetermined period of time. Preferably, a

Sign change of the starting torque at a time or shortly after a time at which a sign change of the rotational movement of the rotor takes place.

In this case, a control device may be provided which regulates the starting torque according to the previously described modulation of the starting torque. In particular, the starting torque between a positive maximum starting torque and a negative minimum starting torque can be controlled, with only the positive maximum starting torque or the negative minimum starting torque is generated by the starter motor.

Corresponds to a sign of the starting torque always the sign of the rotational movement of the rotor of the starter motor, it is operated exclusively in a motor operating mode. According to the invention, a rotation of the crankshaft is mechanically blocked before or at the start time. The mechanical blockage can in this case be carried out, for example, by a blocking agent. For example, the rotation of the crankshaft can be blocked with a crankshaft brake, ie by a frictional connection between the crankshaft and the blocking means. Alternatively, the rotation of the crankshaft can be blocked by a crankshaft lock, ie a positive connection between the crankshaft and the blocking means.

The rotation of the crankshaft is released again when or after energy stored in a torsional vibration system reaches a maximum allowable energy or energy necessary to start the internal combustion engine. Thus, the

Rotation of the crankshaft are released exactly at the time at which the in

Rotational vibration system stored energy the maximum allowable energy or the

Starting the internal combustion engine reaches necessary energy. Alternatively, the rotation of the crankshaft can be released in time after the time at which the stored energy in the torsional vibration system, the maximum allowable energy or the

Starting the internal combustion engine has reached necessary energy. The time difference between reaching the maximum or necessary energy and the release may, for example, be a predetermined period of time, e.g. a period of time needed to achieve a desired phase of torsional vibration.

When the crankshaft is blocked, the torsionally flexible coupling and the rotor of the starter motor and optionally other parts mechanically connected to the rotor form

Torsional vibration system or a so-called rotary oscillator. During the starting process, potential energy stored in torsionally elastic coupling is converted into kinetic energy of the rotor of the starter motor and vice versa. Thus, in each period between two similar sign changes of the rotor speed, there are two times when the potential energy is maximum and the kinetic energy is zero, and two times when the potential energy is zero and the kinetic energy is maximum. During the

When the crankshaft is locked, the starting energy will increase the energy stored in the torsional vibration system, because the energy supplied by the starter motor is greater than the energy dissipated essentially by friction.

The energy required to start the internal combustion engine may be less than the maximum allowable energy. The maximum allowable energy may be, for example, a potential Energy in a state amount of maximum torsions, wherein in the corresponding state, the torsionally flexible coupling is not damaged.

Preferably, the crankshaft rotation is released when the potential energy is zero and the kinetic energy of the torsional vibration system is maximum. In time, this may be the case a quarter of a period after passing through a minimum angle of rotation.

For example, the rotation of the crankshaft can be released even if or after a stored in the torsionally flexible coupling of the rotary vibrator potential energy reaches a maximum allowable energy or in the torsionally flexible coupling of the

Drehschwingers stored potential energy one for starting the

Internal combustion engine reaches necessary energy. A maximum allowable energy in this case is e.g. reached when a twist angle a maximum amount

Twist angle reached. The angle of rotation describes the rotation of the rotor relative to the crankshaft. An energy required for starting the internal combustion engine can be achieved, for example, if a predetermined angle of rotation is achieved which is smaller in magnitude than the maximum permissible angle of rotation. As a result, a power required for the starting process can be reduced in an advantageous manner.

In particular, in cold internal combustion engines, higher starting power is required than with warm internal combustion engines.

The proposed method thus describes a swinging or swinging of the existing of the elastic coupling element and the rotating mass of the rotor mechanical system against a braked crankshaft. If the crankshaft is released again, the energy stored in the oscillated system can be used to drive the crankshaft.

It is also possible that a change in sign of the starting torque takes place in such a time that a resonant frequency of the rotary oscillator is excited. Here, the

Sign change, e.g. occur in time according to the resonance frequency.

It is possible that the blockage of the crankshaft already at a previous one

Switching off or exhibiting the internal combustion engine, eg when parking the vehicle, takes place. Thus, in a subsequent turn on or when activating the ignition described the starting process immediately. The proposed method advantageously makes it possible to use an electric motor with a very low maximum starting torque which can be generated as the starting motor, since no friction losses of the crankshaft during starting by the starter motor have to be compensated for by preventing rotation of the crankshaft.

In another embodiment, the rotation of the crankshaft is released after a minimum allowable during application of a negative starting torque

Verdrehwinkel or a predetermined angle of rotation has been achieved and / or a

Sign change of the starting torque took place. The modulation of the starting torque can thus take place until a minimum permissible angle of rotation is reached, and preferably not exceeded, and a sign change of the negative starting torque to a positive starting torque takes place. In this case, the stored in the rotary oscillator potential energy is transmitted to the crankshaft so that a rotation of the crankshaft takes place in the preferred direction of rotation. Thus, the internal combustion engine can be started in an advantageous manner in the preferred direction of rotation.

Preferably, the release of the rotation of the crankshaft, after a minimum permissible angle of rotation or a predetermined minimum angle of rotation has been achieved during a negative starting torque is applied, a change of sign of

Starting moment and during the subsequent exercise of a positive

An amount of a difference between a current angle of rotation and a zero angle below a predetermined threshold. Thus, the release occurs in the vicinity of the zero crossing of the rotation angle.

Further preferably, after release of the rotation of the crankshaft, only a positive starting torque can be generated by the starter motor and via the elastic motor

Coupling element are transmitted to the crankshaft.

As a result, acting on the released crankshaft in an advantageous manner

Torque maximized, whereby the previously described static friction of the

Internal combustion engine and compression and sliding friction moments of elements of the internal combustion engine can be overcome.

In a further embodiment, after the rotation of the crankshaft has been released, ignition of a fuel-air mixture takes place in a combustion chamber of at least one cylinder of the internal combustion engine. Preferably, an ignition occurs when a Piston of the internal combustion engine during a rotation of the crankshaft in the preferred direction of rotation reaches a top dead center in or after a compression stroke.

The ignition can be a spark ignition or auto-ignition. At a

Ignition, for example, an ignition timing of at least one of the at least one cylinder associated spark plug can be adjusted accordingly. At a

Ignition, for example, a temperature and / or pressure in the combustion chamber can be adjusted accordingly.

By the ignition, which takes place in particular at the time of reaching the top dead center in or after a compression stroke, another, acting in the preferred direction, torque is generated on the crankshaft, which supports the starting process.

In this way, a maximum producible torque of the starter motor can be further reduced.

In a further embodiment, before the blockage of the rotation of the crankshaft, an annulatory torque curve of the starting torque is generated such that a rotation of the crankshaft takes place. Here, the rotation of the crankshaft is mechanically released. In particular, an Aniassmomentenveriauf be generated such that a static friction torque of the crankshaft and of elements, e.g. Piston, the internal combustion engine is overcome and a breakaway of the crankshaft takes place. For example, can be the starting point in the

Aniassmomentenveriauf be generated such that the crankshaft is positioned in a predetermined crankshaft position. The predetermined position may for example be a blocking position, wherein the crankshaft is mechanically blocked only in the blocking position. The Aniassmomentenveriauf can be generated such that it has at least one change of sign (modulation of the starting torque).

Alternatively or cumulatively, the Aniassmomentenveriauf, z. B. with at least one

Sign change of the starting torque, carried out such that the crankshaft is pre-positioned in a predetermined crankshaft position. In this way, advantageously, a starting cylinder and / or a volume of the combustion chamber of the starting cylinder can be adjusted before the starting operation. A start-cylinder describes a cylinder of the internal combustion engine, which in a (released) rotation of the crankshaft in

Preferred direction of rotation as the first of several cylinders reaches its upper compression dead center, wherein the upper compression dead center describes the top dead center in or after a compression stroke. Also, the starting torque curve can be generated such that a predetermined fuel pressure is built up. For this purpose, the crankshaft mechanically or indirectly, for example via a camshaft, drive a pump of a fuel injection system. This is the case in particular in so-called common rail Otto or common rail diesel engines. Thus, advantageously by rotation of the crankshaft before starting the actual starting process, a desired fuel pressure can be built up, which is necessary for subsequent injection and ignition, in particular in diesel internal combustion engines.

This is so even before a mechanical blockage of the rotation of the crankshaft, z. B. generated by a modulation of the starting torque a rotational movement of the crankshaft. However, this rotation does not serve to start the internal combustion engine, but a pressure build-up and / or a pre-positioning of the crankshaft.

In a preferred embodiment, the crankshaft is positioned at a predetermined blocking position prior to the starting time. Here, the blocking position may designate a position of the crankshaft in which rotation of the crankshaft may be blocked.

In particular, the blocking position can be predetermined by a mechanical design of the blocking agent. Preferably, therefore, the blocking means is designed such that it can mechanically block the rotation of the crankshaft in more than one crankshaft position.

The blocking position can also be adjusted depending on a desired start cylinder. Here, the crankshaft can be positioned such that, starting from the current position of the crankshaft, a desired cylinder during a rotation of the crankshaft in the preferred direction of rotation as the first of a plurality of cylinders the upper

Compression dead center reached.

Also, the blocking position depending on a desired volume of a

Combustion chamber of the (start) cylinder can be adjusted. Thus, e.g. a small volume of the (start) cylinder at the beginning of the starting process, an overcoming of the following upper compression dead center, however, an ignition of the

Fuel-air mixture difficult, whereby a labor contribution to overcome the second upper compression dead center is difficult. A big volume of

Combustion chamber at the beginning of the tempering process, however, requires a higher energy to overcome the first following upper compression dead center, however, facilitates the first combustion and thus the further starting process due to the higher working contribution due to the ignition.

Positioning of the crankshaft in a predetermined blocking position can also be achieved with a previous shutdown or shutdown of the internal combustion engine, e.g. by a suitable deceleration of the rotation of the crankshaft. As a result, rotational energy of the crankshaft which is still present when the engine is switched off can advantageously be used to set the desired blocking position.

In another embodiment, a regenerative operation mode of the starter motor is activated when a termination condition of the cranking operation is satisfied after the rotation of the crankshaft is blocked. In the regenerative operating mode is of the

Torsional oscillator generated kinetic energy converted by the operable as a generator starter motor into electrical energy. As a result, the rotational oscillator energy can be withdrawn in an advantageous manner.

If a termination condition of the starting process is satisfied, the blockage of the rotation of the crankshaft can be solved immediately or upon reaching a predetermined counter-torque, wherein the counter-torque denotes the torque exerted by the crankshaft on the elastic coupling torque. As a result, an amplitude of the torsional vibration can be reduced as quickly as possible in an advantageous manner. Alternatively, the mechanical blockade can be solved upon reaching a lower threshold value of a fuel pressure, wherein the lower threshold value defines a fuel pressure, which is a start of the

Internal combustion engine no longer allows safe. Further alternatively, the release of the blockade only at the beginning of a renewed starting operation, but before the proposed start time, take place, for example, when the internal combustion engine is reactivated after a previous shutdown of the internal combustion engine.

A regenerative operation mode of the starter motor may also be activated when the condition (s) for releasing the blockage of the crankshaft is / are satisfied, but the release does not occur due to a malfunction. As a result, the rotary oscillator can be actively deprived of energy, whereby operational reliability is increased.

An abort condition of the starting process can be met, for example, if a defect of the blocking agent and / or its activation is detected. This results in an advantageous manner that a reliability during the

Starting is guaranteed even if energy is already stored in the rotary oscillator, but the starting process must be canceled. This energy can advantageously be converted back into electrical energy by a so-called recuperation, whereby e.g. a battery of the vehicle can be charged.

In a further embodiment, a target torque of the starter motor increases continuously with decreasing difference between a current twist angle and the minimum allowable or the predetermined negative twist angle. Here is a

sign-sensitive consideration of both the desired torque and the difference. This can be done in particular in a half-oscillation from a positive reversal angle to a negative reversal angle, wherein a reversal angle denotes a rotation angle at which a reversal of the direction of rotation of the rotor takes place. If the current angle of rotation approaches the minimum permissible angle of rotation, the difference described above decreases. At the same time, however, the nominal torque of the starter motor increases. Thus, the rotation of the rotor against the preferential direction of rotation, which is caused by a negative target torque, less supported with decreasing difference or, if the target torque is positive, this even counteracted.

As a result, a mechanical damage of the elastic coupling element can be avoided in an advantageous manner, as falling below the minimum allowable or the predetermined negative rotation angle is avoided. Alternatively, the target torque of the starter motor may gradually increase in one or more steps as the difference between the actual twist angle and the minimum allowable or the predetermined negative twist angle decreases. For example, e.g. conceivable that when falling below a predetermined difference, the target torque is suddenly set to a reference value of zero and when reversing the direction of rotation of the rotor or upon reaching the minimum allowable or predetermined negative rotation angle abruptly a positive target torque is set. Another alternative is conceivable that when falling below a predetermined difference, the target torque is suddenly set to a positive or negative target torque.

Alternatively or cumulatively, the target torque of the starter motor decreases with decreasing difference between the maximum permissible angle of rotation or a predetermined positive

Angle of rotation and a current angle of rotation continuously or in one or more Step by step. This can be done in particular in a half-oscillation from a negative angle of return to a positive angle of reversal.

The predetermined negative angle of rotation or the predetermined angle of rotation in this case denote angle of rotation, when it reaches enough energy is stored in the rotary oscillator to start the internal combustion engine.

This results in an advantageous manner an increased reliability in the excitation of the previously described rotary vibrator for starting the internal combustion engine, since permissible angle of rotation is not exceeded or exceeded.

In a further embodiment, a defect of the torsional vibration system is detected if a frequency of the sign change of the starting torque deviates from a predetermined resonance frequency by more than a predetermined amount. Will the sign of the

Starting torque always changed when a reversal of the direction of rotation of the rotor of the starter motor takes place, so times of the sign change can be detected and from this a frequency of the sign change can be determined. If this frequency deviates from a known resonant frequency of the torsional vibration system determined, for example, by tests or modeling, then a defect of the rotary vibrator can be detected.

Alternatively or cumulatively, a defect of the torsional vibration system may be detected when a difference between amounts of the immediately during the starting process

successive reversal angle, for example, the maximum positive and maximum negative rotation angles exceeds a predetermined difference. During the

Starting operation, an amount of the rotation angle may increase continuously. However, this increase is limited by dynamic properties of the rotary oscillator in height.

If the difference of amounts of successive angles of reversal exceeds a predetermined level, the current level during the starting operation increases or decreases

Twist angle so disproportionately on or off. Also in this case, a defect of the torsional vibration system can be detected.

Alternatively or cumulatively, a defect of the torsional vibration system can be detected if a temporal twist angle course deviates from an expected course by more than a predetermined amount. The expected course here denotes a temporal course of the

Twist angle, which will adjust due to the dynamic properties of the rotary vibrator. In a torsionally flexible coupling with linear properties, for example a linear torsion spring, for example, can set as sinusoidal course as expected course.

Alternatively or cumulatively, a defect of the torsional vibration system can be detected when an amount ratio between reversing angles immediately following each other during the starting operation exceeds or falls below a predetermined amount.

Further alternatively or cumulatively, a defect of the torsional vibration system can be detected if a ratio of the mechanical power generated by the starter motor exceeds the predetermined angle of rotation reaches a predetermined level. For this purpose, a current twist angle and the mechanical power generated by the starter motor can be detected or determined. The mechanical power generated by the starter motor can be determined, for example, as a function of an electric power required by the starter motor.

If a defect of the torsional vibration system is detected, then a termination condition of the starting operation can be fulfilled.

This results in an advantageous manner an increase in reliability during a starting operation, since the functionality of the rotary vibrator can be monitored.

Further proposed is a device for starting an internal combustion engine of a motor vehicle. The device comprises at least one internal combustion engine, at least one crankshaft, at least one starter motor, at least one torsionally flexible coupling element and at least one control device. A rotor of the starter motor is mechanically connected via the torsionally flexible coupling element with the crankshaft. By means of the internal combustion engine is a drive torque in a preferred direction of

Internal combustion engine exercisable on the crankshaft. By the starter motor in a starting process, a starting torque can be generated and transmitted via the elastic coupling element to the crankshaft. By means of the control device, the starting torque is adjustable.

According to the invention the device comprises at least one locking means for the crankshaft, wherein by means of the blocking means a rotation of the crankshaft is mechanically blocked and released. In particular, the blocking agent can, as previously explained, as

Crankshaft brake or be designed as a crankshaft lock. The proposed device allows this advantageously the execution of the previously described method.

In a preferred embodiment, the crankshaft and / or the blocking means is / are configured and / or arranged such that a blockage of the rotation of the crankshaft in several crankshaft positions can be carried out. This can advantageously a desired start cylinder and optionally a desired volume of a

Combustion chamber of the start cylinder to be set at the beginning of the starting process.

The invention will be explained in more detail with reference to an embodiment. The figures show:

1 is a schematic block diagram of a drive train,

Fig. 2 is a schematic diagram of a blocking agent in a first

embodiment,

Fig. 3 is a schematic diagram of a blocking agent in a second

Embodiment.

Fig. 4 is a schematic diagram of a blocking agent in a third

Embodiment and

5 shows a schematic time profile of a starting torque, a rotational speed of an internal combustion engine, a rotational speed of the starter motor and an angle of a torsionally flexible coupling element.

Hereinafter, like reference numerals designate elements having the same or similar technical features.

In Fig. 1 is a schematic block diagram of an inventive device 1 for starting an internal combustion engine 2 is shown. The device 1 comprises, in addition to the internal combustion engine 2, a crankshaft 3 of the internal combustion engine 2, a starter motor 4 and a torsionally elastic coupling element 5, by which the crankshaft 3 is mechanically connected to a rotor 6 of the starter motor 4. The torsionally elastic

Coupling element 5 in this case forms the inventive torsionally flexible coupling and may for example be a torsion spring. Furthermore, the device 1 comprises a blocking means 7, by which a rotation of the crankshaft 3 can be mechanically blocked or released. Also shown is a transmission 8, a drive shaft 9 and a rotatable wheel 10 of a motor vehicle which can be driven by the drive shaft 9.

Not shown is a control device which controls the starter motor 4 such that during a starting operation, the starting torque AM generated by the starter motor 4 (see FIG. 5) has at least one, but preferably several, sign changes. At a starting time of the starting operation or before the starting time, the blocking means 7 can be activated, whereby a rotation of the crankshaft 3 is mechanically blocked.

Mechanically blocked here means that a rotation of the crankshaft 3 is not possible. At the starting time, the starter motor 4, e.g. generates a negative starting moment AM. As a result, the rotor 6 of the starter motor 4 against a preferential direction of rotation, which is represented by an arrow 1 1, rotated. Since a rotation of the crankshaft 3 is blocked, the rotor 6 biases the torsionally flexible coupling element 5. Thus, the starting torque AM acts counter to the restoring torque generated by the torsionally flexible coupling element 5.

This increases with a decreasing, thus increasing in magnitude, angle of rotation W (see FIG. 5). If the restoring torque exceeds the torque generated by the starter motor 4 in terms of magnitude, then a reversal of the rotational acceleration takes place. To this

Time or after this time can also be a reversal of direction. At the time of reversal of rotation then takes place a sign change of the starting torque AM, the starter motor 4 generates from this point on a positive starting torque AM and the rotor 6 in the preferred direction of rotation 1 1 drives. A further change of sign to a negative starting torque AM occurs when a renewed reversal of the direction of rotation of the rotor 6 from a direction of rotation in the preferred direction of rotation in a direction of rotation opposite

Preferred direction of rotation. Thus, a swinging of the blocked by

Crankshaft 3, the torsionally flexible coupling element 5 and the rotor 6 formed

Rotational vibrator. During the excitation energy is stored in the rotary oscillator, wherein at the time of reversal of rotation of the rotor 6, the stored energy in the rotary oscillator is completely stored as potential energy.

If a minimum permissible angle of rotation W, that is to say a maximum permissible angle of rotation W, is attained in a rotation of the rotor 6 contrary to the preferential direction of rotation, a sign change of the starting torque AM takes place, as described above. In the following on this change of sign as temporally next zero crossing of the rotation angle W, the blocking means 7 is deactivated, so that the rotation of the crankshaft 3 is released. Thus, in the rotary oscillator at this time as kinetic and Potential energy stored energy at least partially cause a rotation of the crankshaft 3 in the preferred direction of rotation 1 1. The torque transmitted to the crankshaft 3 at this time can advantageously be greater than a breakaway torque and in the

Internal combustion engine 2 be existing compression and sliding friction moments. Thus, the crankshaft 3 can be driven so that the internal combustion engine 2 can be started.

Even before blocking the crankshaft 3, the released crankshaft 3 by a generation of a suitable course of the starting torque AM in a predetermined

Blocking position are positioned. For this purpose, for example, a modulation of the

Starting torque AM occur, so a temporal course of the starting torque AM are generated with at least one change of sign.

The described method for starting the internal combustion engine 2 may be combined with other methods of starting. So it is possible at one

operating warm combustion engine a well-known tow start method

perform the starter motor 4 without activation of the blocking means 7 and without sign change a starting torque AM in the preferred direction of rotation 1 1, that is, a positive starting torque AM, and thus starts the internal combustion engine 2.

Also, the proposed method can be combined with a method in which energy of a rolling vehicle to start or to start the

Internal combustion engine 2 is used by a torque-transmitting connection between a wheel 10 of the vehicle and the internal combustion engine 2 is activated. For example, a control device may determine which method of starting is carried out as a function of input variables such as a temperature of the internal combustion engine 2, a state of the blocking means 7, a vehicle speed, a pedal position and / or a selector lever position. The control device can also monitor the selected method and, if appropriate, stop it and subsequently carry out a different method.

It is also possible that before the blocking of the crankshaft 3 by the blocking means 7, a modulation of the starting torque generated by the starter motor 4 AM is carried out such that a desired fuel pressure is built up. In order to store a maximum possible energy in the rotary oscillator, this will

Starting torque AM controlled such that in a last half period with a negative starting torque AM just a minimum allowable angle of rotation W is achieved, but to avoid damage to the elastic coupling element 5 is not exceeded. If the minimum permissible angle of rotation W of the elastic coupling element 5 is reached, there is a change of sign of the starting torque AM, which is now positive. If now, due to a malfunction, no deactivation of the blocking agent 7, so remains the

Locked crankshaft 3, the starting torque AM can be changed immediately after detection of the malfunction to a minimum value and a regenerative operating mode of

Starter motor 4 are activated. Thus, the starter motor 4 is operated until reaching a maximum angle of rotation W as a generator, whereby the rotary oscillator is actively deprived of energy. In this case, for example, a predetermined number of further deactivation attempts of the blocking agent can take place or it can be the starting process

be canceled.

If, for example, in the case of a failure of the rotary vibrator, the starter motor 4 or the

Blocking means 7, a minimum allowable or a predetermined negative angle of rotation W is not reached after a predetermined period of time, a termination condition of the starting operation can be met. An abort condition can also be met, for example, if an amount ratio of successive reversal angles is one or more times below a predetermined minimum value.

Is the blocking means 7 formed such that the crankshaft 3 only in predetermined

Crankshaft positions can be blocked, so the number of cylinders can be limited, which can be used as a starting cylinder. In this case, a start cylinder is understood to be the one cylinder whose upper compression dead center is first overcome from a predetermined crankshaft position during a rotation of the crankshaft 3 in the preferred direction of rotation 1 1. This can usually, but not necessarily, be the cylinder that is also ignited first. For a four-stroke engine with an even number of cylinders, the number of starting cylinders may be two, for a three-cylinder engine the number is usually one. Is, e.g. due to an embodiment of the blocking means 7, not every cylinder can be used as a start cylinder, so can already when turning off the

Internal combustion engine 2 are positioned by a corresponding crankshaft position control, the crankshaft 3 such that a desired starting cylinder is set. Advantageously, the blocking means 7 is designed or designed such that it can block the rotation of the crankshaft 3 in more than one crankshaft position. For example, the blocking means 7 may be formed so as to equidistant the crankshaft 3 in FIG

Crankshaft positions can block, so every 10 ° crankshaft angle. In this case, the blocking means 7 may be e.g. by a housing, not shown in the

Internal combustion engine 2 fastened radially displaceable bolt may be formed, which can be inserted into bores or recesses, which are introduced into the crankshaft 3.

It is also possible that the blocking means 7 does not directly block a rotation of the crankshaft 3, ie interacts directly with the crankshaft 3, but instead acts on a further shaft, which is coupled to the crankshaft 3, of the internal combustion engine 2, e.g. on a camshaft, acts.

For a reliable cold start of diesel engines is usually a preheating of sucked air and e.g. of parts of a combustion chamber by respective heating or annealing means, e.g. Glow plugs, performed. The proposed method for starting the internal combustion engine 2 in this case advantageously allows a content of a combustion chamber of a cylinder in contrast to conventional

Starting procedure before the first compression does not need to be replaced. This results in an advantageous manner that the heating or annealing means have a longer period over which they can act on the contents of the combustion chamber. Of course, it is conceivable that a cylinder-dependent control of the heating or Glühmittel takes place, so that e.g. a preheating of the starting cylinder or in the combustion chamber of the

Starting cylinder introduced air is more intense or starts earlier. In a spark ignition engine, e.g. in an Otto engine, an ignition energy can be increased in an ignition of the starting cylinder to achieve a reliable ignition. Furthermore, as compared to conventional starting methods, very early fuel pilot injections can take place in the starting cylinder, since, as explained above, the contents of the combustion chamber are no longer exchanged during the starting process and thus a longer time is available for vaporization of the fuel.

The proposed method for starting the internal combustion engine 2 advantageously allows a maximum starting torque AM of the starter motor 4 to be generated to be as small as possible. Under these conditions, it may be advantageous for the internal combustion engine 2 to be as early as possible during the starting process makes its own contribution to torque, possibly already with overcoming the first upper compression dead center.

To determine an injection or ignition timing is usually required that a crankshaft or camshaft angle is known. For example, (absolute) angle sensors can be used to detect such an angle. These can be improved at low resolution by existing incremental sensors. While maintaining conventional incremental sensors on the crankshaft 3 and / or camshaft, a number and a location of signal edges on an early detection of injection angles or

Zündwinkeln be optimized. Such a detection can also take place in an opposite to the preferred direction of rotation 1 1 rotating starter motor 4. When parking the

Internal combustion engine 2 may have information present at that time, e.g. a present crankshaft angle, are used as initial values for a new startup, possibly even after a non-volatile storage when the controllers were switched off in the meantime. It is also possible for information present locally in a control unit to be transmitted via a bus system, e.g. a CAN bus, transmitted

Information of other control units can be compared and only then

Initial values are used if there is no deviation.

If the blocking means 7 is already actuated when the internal combustion engine 2 is switched off and the blocking means 7 remains activated until the next starting of the internal combustion engine 2, the crankshaft angle set at the time of activation of the blocking means 7 can be used as the initial value at the next start.

A rotor angle of the rotor 6, together with a specific crankshaft angle, can be used to determine the angle of rotation W between the crankshaft 3 and the rotor 6 and thus to determine the rotation of the elastic coupling element 5. In this case, the angle of rotation W can be made plausible by predetermined and / or determined torques and / or detected rotational accelerations using mathematical models.

Further, it is possible that means for valve train, such as camshaft phaser, a cylinder shutdown additionally or alternatively to set a predetermined

Control crankshaft position with activated blocking agent 7 such that a predetermined filling of a combustion chamber is set. Furthermore, a defect of the blocking means 7 and / or its activation can be detected. In this case, it can be detected, for example, whether in an activated state of the blocking means 7

Movements of the crankshaft 3 take place. These movements may e.g. be detected by the aforementioned crankshaft or camshaft sensor. In this case, an impermissible movement of the crankshaft 3 can be detected when an amplitude of the movement is above a predetermined value, wherein the predetermined value takes into account an elasticity of the crankshaft 3 and the blocking means 7.

Alternatively, the blocking means 7 may be provided with means for detecting an engagement path, e.g. of pins or a locking bar 18 (see, for example, Fig. 2), wherein in an engaged state, the rotation of the crankshaft 3 is blocked. Changes one

Output of the means for detecting the Einrückweges in an activation not in a predetermined manner, so a defect can be detected.

In the case of an electromagnet used as an actuator for the blocking means 7, a current waveform in windings of the electromagnet or a variation of an inductance of the electromagnet, e.g. depending on a current gradient for a given

Voltage jump to be detected, wherein a defect is detected when these sizes deviate from predetermined sizes.

In the case of an electric motor as an actuator for the blocking means 7 can be detected whether a rotation of the rotor of the electric motor corresponds to a desired rotation upon activation of the blocking means 7, whether a voltage is induced in the electric motor or a current consumption of the electric motor deviates from a predetermined current consumption. It is also possible to detect whether there is no commutation in the case of a BLDC motor.

A defect of the blocking means 7 can also be detected if, after a deactivation of the blocking means 7, no or only a slight movement of the crankshaft 3 occurs for a predetermined period of time.

Fig. 2 shows a schematic diagram of a blocking means 7 in a first

Embodiment. The blocking means 7 comprises a gear 12, which is rotatably mounted about a central axis of rotation 13. The gear 12 may be fixed in a torsionally rigid manner on the crankshaft 3 (see FIG. 1). In this case, the gear 12 teeth 14, each having a rounded portion 15 and a straight portion 16. Here, the teeth 14 in a cross section with a sectional plane perpendicular to the central axis of rotation 13 a quarter-circular cross-section. The straight sections 16 in this case run in the radial direction with respect to a center 17 of the gear 12.

Further, the blocking means 7 comprises a locking bar 18 which is rotatable about a

Rotation axis 19 of the locking bar 18 is mounted. The latching bar 18 has at a gear-side end a latching lug 20, wherein the latching lug 20 can interact with the teeth 14. The rounded portions 15 of the teeth 14 are in this case designed such that when the gear 12 rotates in the counterclockwise direction, which is relative to the central axis of rotation 13 rotates, a tip 21 of the locking tooth 20 along the rounded tooth surface of the teeth 14 can slide without latching with your teeth. In this case, a rotational movement of the gear 12 and thus also the crankshaft 3 is released. The straight portions 16 of the teeth 14 are in this case designed such that when the gear 12 rotates clockwise, formed by the locking lug 20 abutment surface 22 abuts the straight portion 16, whereby the gear 12 is locked to the locking bar 18. In this case, a rotational movement of the gear 12 and thus also the crankshaft 3 is locked.

The blocking means 7 further comprises a first spring 23 and a further spring 24. In this case, the further spring 24 is attached to a latching nose side portion of the locking bar 18, wherein the first spring with respect to the axis of rotation 19 of the locking bar 18 on a detent side portion opposite portion of Rastbalkens 18 is attached. Furthermore, the blocking means 7 comprises an actuator 25, which can move the further spring 24 in or against a vertical direction, which is represented by an arrow 26. In a

Release position, the other spring 24 is positioned by the actuator 25 in a vertical direction 26 upper position. In this release position exercises, in particular exclusively, the first spring 23 a force on the locking bar 18, so that the locking lug 20 moves due to the rotation of the locking bar about the rotation axis 19 against the vertical direction 26 shown in FIG. 3 upwards and thus the Rotary movement of the gear 12 releases in both directions of rotation.

In a blocking position, the further spring 24 by the actuator 25 in an in

Vertical direction 26 positioned lower position. In this case, both the first spring 23 and the further spring 24 exerts a force in the vertical direction 26 on the latching bar 18. Since both forces, with respect to the axis of rotation 19, act on opposite portions of the locking bar 18, there is no rotation of the locking bar 18 and thus no release of

Rotary movement in both directions of rotation. Rather, in this blocking position is the Rotary movement of the gear 12 locked in a clockwise direction. Counterclockwise, the rotational movement, as previously described, against the spring force of the other spring 24 is possible.

Fig. 3 shows a schematic diagram of a blocking means 7 in a second

Embodiment. The blocking means 7 comprises a gear 12, which is rotatably mounted about a central axis of rotation 13. The gear 12 may be fixed in a torsionally rigid manner on the crankshaft 3 (see FIG. 1). Here, the gear 12 teeth 14, wherein the teeth 14 in a cross section with a sectional plane perpendicular to the central axis of rotation 13 have a trapezoidal cross-section.

Next, the blocking means 7 comprises a locking bar 18 which is rotatably mounted about a rotation axis 19 of the locking bar 18. The latching bar 18 has at a gear-side end on a locking lug 20 with also trapezoidal cross-section, wherein the latching lug 20 can interact with the teeth 14. The blocking means 7 further comprises a first spring 23 and a further spring 24. In this case, the further spring 24 is attached to a latching nose side portion of the locking bar 18, wherein the first spring 23 with respect to the axis of rotation 19 of the locking bar 18 on a detent side portion opposite section of the locking bar 18 is attached. Furthermore, the blocking means 7 comprises an actuator 25, which can move the further spring 24 in a vertical direction, which is represented by an arrow 26. In a release position, the further spring 24 is positioned by the actuator 25 in a vertical direction 26 upper position. In this release position, in particular exclusively, the first spring 23 exerts a force on the latching bar 18, so that the latching lug 20 moves upward due to the rotation of the latching bar 18 about the rotation axis 19 against the vertical direction 26 shown in FIG. 3 and thus the rotational movement of the gear 12 releases in both directions of rotation.

In a blocking position, the further spring 24 by the actuator 25 in an in

Vertical direction 26 positioned lower position. In this blocking position, both the first spring 23 and the further spring 24 exert a force in the vertical direction on the latching bar 18. Since both forces act on, with respect to the axis of rotation 19, opposite portions of the locking bar 18, there is no rotation of the locking bar 18 and thus no release of both rotational movement. Rather, the rotational movement of the gear 12 is locked in both directions of rotation in this blocking position. 4 shows a schematic diagram of a blocking means 7 in a third

Embodiment. The blocking means 7 comprises two brake pads 27, the on

opposite sides of the crankshaft 3 (see Fig. 1) are arranged. Furthermore, the blocking means 7 comprises an actuator 25, which can be moved in and against a longitudinal direction, which is symbolized by an arrow 28. Furthermore, the blocking means 7 comprises the respective brake pads 27 associated lever arms 29 which are each rotatably mounted about rotation axes 30. In this case, the axes of rotation 30 extend perpendicular to the longitudinal direction 28. FIG. 4 shows that the lever arms 29 have two arm sections. A first

Arm portion 31 extends from the axis of rotation 30 to the corresponding brake pad 27. A second arm portion 32 extends away from the brake pad 27 and encloses an angle α with the first arm portion. At a free end of the second

Arm portion 32, the lever arm 29 mechanically with the actuator 25, e.g. via a pull rope, connected. Furthermore, the blocking means 7 comprises a spring 33 which is arranged between the brake pads 27. In an initial position of the spring 33, in which the spring is not biased, the brake pads 27 are not in mechanical contact with the crankshaft 3. If now the actuator 25 moved in the longitudinal direction 28, the brake pads 27 due to the mechanical connection of the actuator 25th pressed with the lever arms 29 and due to the formation and storage of the lever arms 29 against the spring force generated by the spring 33 to the crankshaft 3, whereby a mechanical contact between the brake pads 27 and the crankshaft 3 is made and the crankshaft 3 is braked. In this

Blocking state, a rotational movement of the crankshaft 3 is not possible. If the actuator 25 is moved counter to the longitudinal direction 28, the brake pads are moved away from the crankshaft 3 by the spring force generated by the spring 33. As a result, a release state is achieved in which a rotational movement of the crankshaft 3 is released.

Fig. 5 shows a schematic course of a starting torque AM by a

a solid line, a rotational speed DV of an internal combustion engine 2 (see Fig. 1) by a dashed line, a rotational speed DA of the starter motor 4 by a dash-dot line and a rotation angle W of a torsionally flexible coupling element 5 by a dotted line over a time t.

In a first phase P1, a modulation of the starting torque AM takes place such that the crankshaft 3 breaks loose. This takes place at the end time E_P1 of the first phase P1. In a second phase P2, the starting torque AM is modulated in such a way that the crankshaft 3 is moved in a predetermined angular range in such a way that a fuel pump coupled to the crankshaft 3 can build up a desired injection pressure. From the End time E_P2 the second phase P2, the starting torque AM is controlled such that the crankshaft 3 is positioned in a crankshaft position in which a blockage of the crankshaft 3 is possible. At a blocking time B, the rotational movement of the crankshaft 3 is blocked. In a fourth phase P4 energy is now accumulated in the above-explained rotary oscillator, with maximum and minimum amplitudes of the speed DA and the angle W increase. After an end time E_P4 the fourth phase P4 takes place in a fifth phase P5, a release of the blockade, which increases at a release time L, the speed DV of the internal combustion engine 2 temporally fast, for example, jump-like.

It is also possible to control the blocking means 7 before the blocking time 3 and / or before the release time L.

Thus, side surfaces of the teeth 14 and the detent 20 (see Figs. 2 and 3) may be frictionally engaged when a force acts on these surfaces, e.g. during a blockage of the crankshaft 3. This force is essentially dependent on a twist angle W of the elastic coupling element 5. In particular, the frictional force generated by the frictional connection can prevent release, for example when the frictional force is greater than the lifting force exerted by the springs 23, 24 on the detent bar 18. However, the frictional force will be low when the elastic coupling element 5 is relaxed, that is, has a magnitude small angle of rotation W.

Thus, the time interval in which the blocking means 7 should release the rotation of the crankshaft 3 is small. During the fourth phase P1, a period duration, that is to say a time duration between two successive identical sign changes of the direction of rotation, can be for example approximately 120 ms. Thus, even temporally successive magnitude maxima of the angle of rotation W are only about 60 ms apart. As a result, a time interval for release can include periods of time from 0 ms to 20 ms.

In general, the cost and space requirements of an actuator, e.g. of the actuator 25 shown in FIGS. 2 and 3, of the blocking means 7 with increasing maximum power, which is determined from the product of force and travel per actuating time. Thus, if a positioning time, which in this case corresponds to the duration of the release of the rotation, increased, so costs and space can be reduced.

In an advantageous design of the blocking means 7 so instead of a direct mechanical coupling of the actuator 25 with the locking bar 18 is a mechanical coupling realized via the further spring 24. This further spring 24 serves as a temporary storage for a generated by the actuator 25 point energy.

If the actuator 25 is e.g. designed as an electric motor, possibly with a gear, so this actuator 25 can be controlled even before the release time L, at the latest to the release time L, a movement of the locking bar 18 should be made. This control can be maintained until the end of the movement of the locking bar 18 or even beyond.

If the adjusting device of the blocking means 7, thus e.g. the actuator 25, via a spring, for example the further spring 24, with a release element, e.g. the locking bar 18, the actuator 25 may be actuated at a driving time which is a predetermined period, e.g. 70 ms, before the desired release time L is controlled such that a Aktorseitiges end of the other spring 24 in a release direction, which is oriented in this case against the vertical direction 26, is moved. From this point on, e.g. a motor of the actuator 25 accelerates. The spring force which builds up during this movement in the release direction, which accelerates the release element, that is to say the latching bar 18, likewise in the release direction, does not exceed the previously explained frictional force until a further point in time, which is later than the actuation time and before the release time L, which is generated by the angle of rotation W of the elastic coupling element 5 dependent frictional connection between the teeth 14 and the locking tooth 20. Here, the driving time and the driving force generated by the actuator 25 is selected in dependence on a time course of the angle of rotation W of the elastic coupling element 5, that the spring force exceeds the frictional force for the previously explained further time and thus accelerates the locking bar 18 in the release direction and thus moved. In such a method, the release time L is thus set virtually automatically.

In this case, only the locking bar 18 and a part of the other spring 24 must be accelerated, and in the case of a direct mechanical coupling of the actuator 25 with the locking bar 18 also has an optionally connected via a gear with the other spring 24 rotor of the actuator 25 and accelerate thus a comparatively larger moment of inertia would have to be overcome. This would require a higher performance of the actuator 25.

In the illustrated in Fig. 3 trapezoidal cross-sections of the teeth 14 and the locking lug 20 decreases with increasingly traveled path of the locking bar 18 in the release direction of Distance between a tooth 14 and the locking lug 20 to continuously, so that after the start of the movement of the locking bar 18, the probability of undesirable re-contact of the side surfaces, which would cause a frictional force-based braking of the locking bar 18 decreases. The locking bar 18 is thus accelerated unrestrained. The spring force hardly decreases here, since the actuator 25 now moves the actuator-side end of the further spring 24 correspondingly faster.

Accordingly, a control of the blocking means 7 take place before the blocking time B, wherein the frictional force when moving the latching lug 20 against the release direction, ie in the vertical direction 26, is overcome.

The increasing angle of rotation W of the elastic coupling element 5 causes an increasing torque on the crankshaft 3, which is accelerated. The locking bar 18 is now so far moved in the release direction 18 that no mechanical contact between the teeth 14 and the locking lug 20 may occur more.

After this, the activation of the actuator 25 can be switched off.

In the foregoing, the method of prematurely driving an actuator of the blocking means 7 for the embodiments shown in FIGS. 2 and 3 has been explained. Of course, the described method is also executable for further embodiments of the blocking means 7, in particular for embodiments in which the adjusting device of the blocking means 7 is connected via an elastic element with a release element. In this case, in time before a blocking time B and / or before a desired release time L, the adjusting device can be controlled such that a device-side end of the elastic member is moved towards or in a release direction. In this case, a control time and / or the force generated by the adjusting device can be selected depending on a time profile of the angle of rotation W of the elastic coupling element 5, that at a further time the force of the elastic element on the release element a frictional force between the release element and a crankshaft side corresponding element of the blocking agent exceeds. LIST OF REFERENCE NUMBERS

contraption

Internal combustion engine

crankshaft

starter motor

elastic coupling element

rotor

blocking agent

transmission

drive shaft

wheel

Preferred direction of rotation

gear

rotation axis

tooth

rounded section

straight section

Focus

Rest bar

axis of rotation

locking lug

top

stop surface

first spring

another spring

actuator

vertical direction

brake pads

longitudinal direction

lever arm

axis of rotation

first arm section

another arm section

feather

starting torque DA speed of the starter motor

DV speed of the internal combustion engine

W twist angle

P1 first phase

P2 second phase

P3 third phase

P4 fourth phase

P5 fifth phase

E_P1 End time of the first phase

E_P2 End time of the second phase

B blocking time

E_P4 End time of the fourth phase

L release date

t time

Claims

claims

Method for starting an internal combustion engine (2), wherein a

Crankshaft (3) is torsionally elastic coupled to a rotor (6) of a starter motor (4), wherein in a starting operation of the starter motor (4) generates a starting torque (AM), which is transmitted via the torsionally flexible coupling to the crankshaft (3) at a starting time of the starting process a negative or positive

Anchor torque (AM) is generated, wherein at least one change of sign of the starting torque (AM) takes place during the starting process,

characterized in that

Before or at the start time, a rotation of the crankshaft (3) is mechanically blocked, wherein the rotation of the crankshaft (3) is released, if or after an energy stored in a torsional vibration system, a maximum allowable energy or an energy required for starting the internal combustion engine (2) achieved, wherein the torsional vibration system consists of at least the torsionally flexible coupling and the rotor (6) of the starter motor (4).

A method according to claim 1, characterized in that the rotation of the

Crankshaft (3) is released after during a negative starting torque (AM) a minimum allowable twist angle (W) or a predetermined negative twist angle (W) has been reached and / or a change in sign of the starting torque (AM).

Method according to one of claims 1 or 2, characterized in that after release of the rotation of the crankshaft (3) ignition of a fuel-air mixture in a combustion chamber of at least one cylinder of the

Internal combustion engine (2) takes place.

Method according to one of claims 1 to 3, characterized in that before the blockage of the rotation of the crankshaft (3) a starting torque curve of

Starting torque (AM) is generated such that a rotation of the crankshaft (3) takes place.

Method according to one of claims 1 to 4, characterized in that the

Crankshaft (3) is positioned in a predetermined blocking position before the start time. Method according to one of claims 1 to 5, characterized in that when a termination condition of the starting operation is satisfied after the rotation of the

Crankshaft (3) was blocked, a generator operating mode of the starter motor (4) is activated.

Method according to one of claims 1 to 6, characterized in that a

Nominal torque of the starter motor (4) with decreasing difference between a current twist angle (W) and the minimum allowable or the predetermined negative twist angle (W) continuously increases or gradually increases in one or more steps and / or that the target torque of the starter motor (4)

decreasing difference between the maximum allowable twist angle (W) or a predetermined positive twist angle (W) and a current twist angle (W) continuously decreases or gradually decreases in one or more steps.

Method according to one of claims 1 to 7, characterized in that a defect of the torsional vibration system is detected if a frequency of the sign change of the starting torque (AM) by more than a predetermined amount deviates from a predetermined resonant frequency and / or a difference between the amounts during of the starting process immediately consecutive positive and negative

Reversing angle exceeds a predetermined difference and / or a deviation of a temporal twist angle course of an expected course exceeds a predetermined level and / or an amount ratio between during the starting process immediately consecutive positive and negative reversal angles below or exceeds a predetermined amount and / / or a ratio of the

Starter motor generated mechanical power to the achieved twist angle (W) exceeds a predetermined level.

Device for starting an internal combustion engine (2) of a motor vehicle, comprising at least one internal combustion engine (2), at least one

Crankshaft (3), at least one starter motor (4), at least one torsionally flexible coupling element (5) and at least one control device,

wherein a rotor (6) of the starter motor (4) is mechanically connected to the crankshaft (3) via the torsionally flexible coupling element (5),

wherein by means of the internal combustion engine (2) has a drive torque in a

Preferred direction of the internal combustion engine (2) on the crankshaft (3) is exercisable, wherein by the starter motor (4) in a starting process, a starting torque (AM) can be generated and via the elastic coupling element (5) on the crankshaft (3) is transferable, said means the control device the starting torque (AM) is controllable, characterized in that

the device (1) comprises at least one blocking means (7) for the crankshaft (3), wherein by means of the blocking means (7), a rotation of the crankshaft (3) is mechanically blocked and releasable.

Apparatus according to claim 9, characterized in that the crankshaft (3) and / or the blocking means (7) is configured and / or arranged such that a

Blockage of the rotation of the crankshaft (3) in several crankshaft positions

is feasible.