DE102016202138A1 - Method for starting an internal combustion engine and drive train for a motor vehicle - Google Patents

Abstract

The invention relates to a method for starting an internal combustion engine (2) having an output shaft (5) of a motor vehicle in which the output shaft (5) is driven to start the internal combustion engine (2), the output shaft (5) being connected via a clutch device (13). is coupled to a flywheel (10) by means of an actuator (14) the initially opened coupling means (13) is closed, thereby for starting the internal combustion engine (2) the output shaft (5) exclusively by means of in the rotating flywheel (10) stored To drive rotational energy.

Description

The invention relates to a method for starting an internal combustion engine according to the preamble of patent claim 1 and to a drive train for a motor vehicle according to the preamble of patent claim 10.

Such methods for starting internal combustion engines of motor vehicles and drive trains for motor vehicles are already well known from the general state of the art. As part of the process, an output shaft of the internal combustion engine is driven to start the internal combustion engine. In particular, it is usually provided to drive the output shaft of the internal combustion engine by means of an electric motor, wherein the output shaft is usually driven until combustion processes take place in the internal combustion engine, in particular in at least one combustion chamber of the internal combustion engine, by means of which the output shaft, in particular without the aid of the electric motor , can be driven. For this purpose, the output shaft is brought by means of the electric motor to a sufficient speed by the output shaft is driven by means of the electric motor.

In its fired operation, the internal combustion engine provides torques for driving the motor vehicle via the output shaft. If the internal combustion engine is designed, for example, as a reciprocating piston engine, the output shaft is usually a crankshaft.

The DE 10 2009 008 599 A1 discloses a flywheel fixedly received on an output shaft of an internal combustion engine and having a starter ring gear for starting the engine by means of a starter. From the WO 2010/130058 A1 is a starter device for starting, that is starting, an internal combustion engine known. Furthermore, the DE 10 2010 012 514 A1 a device for starting an internal combustion engine by means of a starter motor. In addition, the disclosed DE 29 43 554 A1 a hybrid drive for a vehicle. Finally, that is DE 10 2010 054 287 A1 a flywheel for an internal combustion engine known.

Furthermore, it is known from the general state of the art to equip motor vehicles with so-called start-stop automatic systems in order to reduce fuel consumption and pollutant emissions. By means of such a start-stop automatic system, the internal combustion engine under certain conditions or in the presence of predetermined switch-off automatically, that is switched off by means of an electronic computing device of the motor vehicle and automatically started in the presence of predetermined Anschaltbedingungen. The automatic starting or starting of the internal combustion engine after an automatic shutdown of the internal combustion engine is also referred to as restart. One possible condition for initiating an automatic switch-off process is, for example, that the driving speed of the motor vehicle at a certain point in time is below a predetermined limit value. Conversely, an automatic start of the internal combustion engine is initiated as soon as the brake pedal is released or the accelerator pedal or - especially when using a manual gearbox - the clutch pedal and thus the clutch are actuated. Usually, the accelerator pedal is also referred to as an accelerator pedal.

After the internal combustion engine has been switched off, it must, for example, at the end of a start-stop phase, restarted, that is tempered. For this purpose, usually an electric starter, that is, the aforementioned electric motor used. If, for example, a so-called pinion starter is used as the starting system, then meshing or starting of the internal combustion engine is not possible if it is still running, that is, if the output shaft is still rotating, or starting the still running internal combustion engine is associated with loss of comfort, since the pinion starter only with fully shut off internal combustion engine, that is, when the output shaft is at a standstill, can track. This means that a conventional pinion starter can only engage in a starter ring, which is also referred to as starter ring gear, when the internal combustion engine is at a standstill, in order subsequently to initiate the restart, for example. This leads inter alia to a deteriorated response of the internal combustion engine and adds up to a considerably perceived time delay. Above all, the start-up behavior of the internal combustion engine or of the motor vehicle as a whole is judged to be sluggish and annoying, especially when renewed acceleration desired during the shutdown process, a so-called change-of-mind case.

Object of the present invention is therefore to further develop a method and a drive train of the type mentioned in such a way that a particularly advantageous and fast starting or starting the internal combustion engine, in particular after an automatic shutdown of the internal combustion engine, can be realized.

This object is achieved by a method having the features of patent claim 1 and by a drive train with the features of claim 10. Advantageous embodiments of the invention are the subject of the dependent claims.

In order to develop a method specified in the preamble of claim 1 type such that the internal combustion engine particularly advantageous and particularly fast, especially after an automatic shutdown of the internal combustion engine, started, that can be tempered, it is inventively provided that the output shaft via a Coupling device is coupled to the flywheel by means of an actuator, the initially opened coupling device is closed - in particular while the flywheel rotates - thereby to drive to start the internal combustion engine, the output shaft exclusively by means stored in the rotating flywheel rotation energy. This means that the output shaft is driven exclusively by means of the rotating flywheel, that is exclusively by means stored in the rotating flywheel energy and thus without switching an electromotive torque generated due to the closing of the clutch device, so that an electric motor driving the Abtrieswelle is omitted. In other words, when starting the internal combustion engine, an electric motor driving the output shaft is omitted, so that the internal combustion engine is started exclusively by means of the rotating flywheel, without an electromotive torque generated is used to start the internal combustion engine. Expressed again in other words is provided in the context of the method according to the invention that in the context of starting the internal combustion engine caused by an electric motor driving the output shaft is omitted, so there is no torque flow from an electric motor to the drive shaft.

The invention is based in particular on the finding that the use of a conventional pinion starter, which latches for starting an internal combustion engine in a starter ring gear, has the following disadvantages: limited power of the pinion starter, so that a low towing speed leads to long engine start times; high power consumption of the pinion starter, resulting in an additional load on a vehicle electrical system of the motor vehicle; uncomfortable engine start due to an external torque acting on the internal combustion engine from the pinion starter, extended engine start time in change-of-mind situations, resulting in a low reflex start ability on renewed acceleration request after switching off the internal combustion engine.

The internal combustion engine is also referred to as an engine or internal combustion engine, so that a time required for starting or starting the internal combustion engine is also referred to as start time or engine start time. By means of the method according to the invention, the engine start time can be kept particularly low. Furthermore, the energy required to start the internal combustion engine can be kept low, since only the rotating flywheel or stored in the rotating flywheel rotational energy is used for fast acceleration or driving the output shaft. In other words, all the disadvantages mentioned above in connection with the pinion starter can be avoided by means of the method according to the invention.

The method according to the invention is particularly advantageously used in a start-stop automatic system in which, for example, when at least one predeterminable first criterion is met, the internal combustion engine is automatically switched off, that is to say by means of an electronic computing device of the motor vehicle. The electronic computing device is usually also referred to as a control unit. If at least one predefinable second criterion is met, the internal combustion engine is started automatically, that is to say by means of the electronic computing device, that is, it is started, the method according to the invention being carried out during the starting of the internal combustion engine. The aforementioned change-of-mind situation is to be understood, for example, as a situation in which the driver of the motor vehicle initially behaves in such a way that the at least one first criterion is satisfied, so that an automatic shut-down process, within the scope of which the internal combustion engine automatically shuts off will be initiated. Shortly after fulfillment of the at least one first criterion, however, the driver behaves in such a way that the at least one second criterion is satisfied, so that an automatic startup process is then initiated shortly after the initiation or shortly after the end of the automatic shutdown process, within the scope of which the internal combustion engine the electronic computing device is started automatically.

The automatic starting or starting of the internal combustion engine effected by means of the electronic computing device is also referred to as restarting. In conventional pinion starters, the restart can take place only very slowly shortly after the automatic shutdown, so that the internal combustion engine only can be restarted very slowly. By means of the method according to the invention, however, it is possible to restart the internal combustion engine particularly quickly and quickly, even in a change-of-mind situation, so that the driver, for example, continue the journey very shortly after the end or after the automatic switch-off has been initiated and, for example, that Can accelerate the motor vehicle by means of the internal combustion engine. By means of the method according to the invention, it is thus possible to create a particularly reflexive start-stop automatic system in order, for example, to make a starting operation particularly fast and comfortable in the context of automatic starting of the internal combustion engine. Under the reflexive automatic start-stop system is to be understood in particular that the internal combustion engine in a previously described change-of-mind situation particularly fast, ie in a particularly short time and thus can be quickly restarted without causing excessive delays or Dead times comes.

In particular, the following situation is used in such a restart: Before the automatic shutdown of the internal combustion engine caused by the computing device, the clutch device is closed in order to drive the motor vehicle by means of the internal combustion engine via its output shaft. In this case, the flywheel is driven by means of the internal combustion engine via the output shaft and via the closed coupling device, so that the flywheel rotates.

As part of an automatic shutdown, the coupling device is opened by means of the computing device, so that the internal combustion engine is not stalled uncontrollably, for example, when stopping the motor vehicle. After opening the clutch device, the internal combustion engine is automatically switched off by means of the computing device. The flywheel continues to rotate when the clutch device is opened due to its inertia. In particular, the flywheel rotates due to its high inertia while the clutch device is open. By opening the coupling device, the flywheel or the rotation of the flywheel is not affected by the automatic shutdown of the internal combustion engine. Thus, a high rotational energy is stored in the rotating flywheel, while the clutch device is opened and the internal combustion engine is switched off.

If the driver of the motor vehicle wishes to continue driving after stopping, the internal combustion engine is automatically started during the restart. For this purpose, the stored in the still rotating flywheel rotational energy is used to drive the output shaft in the context of the restart only by means of the rotational energy stored in the rotating flywheel - and not with the help of an electric motor. The coupling device is thereby closed in order to drive the output shaft exclusively by means of the rotational energy stored in the rotating flywheel mass and, as a consequence, to automatically start the internal combustion engine, preferably without the aid of an electric motor and in particular without a torque flow from an electric motor to the output shaft.

Another advantage is that the flywheel does not belong to the internal combustion engine or is not part of the internal combustion engine, but the flywheel is based on a torque flow from the output shaft to the flywheel after or downstream of the clutch device arranged so that the internal combustion engine are designed in cost and weight can.

In an advantageous embodiment of the invention, a first step is provided in which the flywheel is driven by an electric machine, in particular an electric motor, while the coupling device is open, whereby at least the flywheel, in particular the flywheel and the electric machine, decoupled from the output shaft is or is. This is omitted Torque flow from the electric machine to or on the output shaft. In other words, the flywheel is driven by the electric machine, in particular rotated about an axis of rotation, while at least the flywheel, in particular the flywheel and the electric machine is decoupled from the output shaft or are. To drive the flywheel, the electric machine is operated for example in a motor operation and thus as an electric motor.

Furthermore, a second step is provided in which the coupling device is closed by means of the actuator, whereby the output shaft is coupled via the coupling device at least with the flywheel, in particular with the flywheel and the electric machine. Preferably, the second step follows in time to the first step, so that the output shaft is coupled as a result of the closing of the coupling device with the in motion, that is rotating rotating mass via the coupling device. In this case, preferably a torque flow from the electric machine to the output shaft is omitted. The flywheel is in motion, since it is or was driven by means of the electric machine, at least before the closing of the coupling device. The electric machine is therefore preferably used only to drive the flywheel or to keep turning, in particular while the clutch device is open. As a result of the closing of the clutch device, the output shaft is coupled via the closed coupling device at least with the rotating flywheel or connected, in particular rotatably connected, so that the output shaft driven by the rotating coupling means of the rotating flywheel, in particular accelerated, is. In this way, the output shaft can be brought to a sufficiently high speed particularly advantageous and fast, so that the internal combustion engine, especially after an automatic shutdown of the internal combustion engine, particularly quickly restarted, that is, can be started.

Preferably, this also omits a driven by the electric machine driving the output shaft, that is, a torque flow from the electric machine to the output shaft, so that the output shaft - in the context of starting the internal combustion engine - is driven exclusively by means of stored energy in the rotating flywheel. As a result, the current consumption of the electric machine can be kept low because the rotating flywheel is used for fast acceleration or driving of the output shaft

In an advantageous embodiment of the invention, the flywheel, in particular the flywheel and the output shaft, after closing the clutch device at least temporarily driven by the electric machine, while the clutch device is closed. As a result, the output shaft, in particular after an automatic shutdown of the internal combustion engine, are brought to a sufficiently high speed particularly fast to start the internal combustion engine particularly advantageous or to accelerate the motor vehicle particularly quickly.

If the electric machine is used, it is preferably a separately formed from the flywheel and in addition to the flywheel provided component, which preferably desachsiert, that is non-coaxial with the flywheel is arranged. In particular, it is provided that the flywheel is not integrated into the optional electric machine used.

The coupling device is adjustable, for example, between at least one open state and at least one closed state, in particular by means of the actuator. The actuator is, for example, an electric or electrically operable, pneumatic or pneumatically operable or hydraulic or hydraulically operable actuator, by means of which the coupling between the open state and the closed state can be adjusted. In the closed state of the clutch device, the output shaft, in particular rotationally fixed, coupled to the flywheel, so that torques between the flywheel and the output shaft, in particular from the flywheel to the output shaft, can be transmitted via the coupling device. In the open state, however, the output shaft is decoupled from the flywheel, so that no torque between the output shaft and the flywheel can be transmitted via the coupling device.

The adjustment of the clutch device from the open state to the closed state is referred to as closing the clutch device, wherein the adjustment of the clutch device from the closed state to the open state is referred to as opening of the clutch device. In the optional use of the electric machine, it is possible to first drive the flywheel by means of the electric machine or to keep it at a sufficiently high speed while the clutch device is open, so that although the flywheel, but not the output shaft is driven by the electric machine.

Under the means of the electric machine caused driving the flywheel is to be understood that the flywheel is rotated by means of the electric machine about a rotation axis. For example, the flywheel is arranged coaxially to the output shaft, so that, for example, the output shaft is rotatable about the axis of rotation about which the flywheel is rotatable. If the coupling device is closed while the flywheel is still rotating as a result of the driven by the electric machine driving the flywheel and / or while the flywheel is still driven by the electric machine, so that the output shaft is particularly fast, that is in a very short time over the coupling device accelerated by the rotating flywheel and brought to a sufficiently high speed to start the internal combustion engine particularly advantageous and fast, that is to say to start.

In the context of the automatic shutdown of the internal combustion engine described above, the coupling device, in particular by means of the actuator, for example, automatically open. Since the clutch device was previously closed, the flywheel was previously driven, for example, by the output shaft, so that the flywheel still rotates after opening the clutch device. After opening the coupling device, the electric machine is used, for example, to keep the still rotating flywheel at a sufficiently high speed. If then the clutch device is closed again as part of the starting of the internal combustion engine, the flywheel on a particularly advantageous and sufficiently high speed to accelerate the output shaft particularly advantageous and start the internal combustion engine very quickly, that is, start to. The optionally used electrical machine thus has to spend only a small amount of energy in order to drive the flywheel and thus to keep it at a sufficiently high speed, so that the energy consumption, in particular the power consumption, of the electric machine can be kept very low. In the context of the method according to the invention, in particular the rotational energy stored in the rotating flywheel, that is to say the kinetic energy of the rotating flywheel, is used to start the internal combustion engine. The electric machine is optionally used in particular to overcome frictional forces and thereby keep the initially rotating flywheel at a sufficiently high or advantageous speed.

The use of the electric machine also allows the realization of a so-called initial start. As part of the initial start, the flywheel is initially silent because the motor vehicle, for example, was already parked for a long time or parked. In the course of the initial start, for example, the initially stationary, that is, not rotating flywheel can be driven by the electric machine, that is rotated and thereby be brought to a predetermined speed, for example, while the coupling device is initially still open. Then the initially opened coupling device is used with rotating flywheel to drive the output shaft exclusively by means of the stored energy in the rotating flywheel and start the internal combustion engine as a result.

In a further embodiment of the invention, the closing of the coupling device is effected by means of the electronic computing device of the motor vehicle. In other words, the coupling device is automatically closed by means of the electronic computing device. As a result, a particularly needs-based closing of the clutch can be realized, so that the internal combustion engine can be started particularly advantageous and fast.

Another embodiment is characterized in that the coupling device is closed when the flywheel has a non-zero, predetermined speed. In other words, for example, a comparison between an actual rotational speed of the flywheel and a desired rotational speed of the flywheel, wherein the actual rotational speed of the flywheel is detected for example by means of at least one sensor. If the comparison reveals that the actual rotational speed of the flywheel mass corresponds to the non-zero desired value or is greater than the desired value, then the clutch device is closed so as to allow the internal combustion engine to start particularly advantageously.

In a further embodiment of the invention, a flywheel, in particular a dual mass flywheel (DMF), is used as the flywheel. As a result, the flywheel has a particularly advantageous inertia, in particular inertia, so that the flywheel, in particular its kinetic energy, can be used particularly well for starting the internal combustion engine. Furthermore, this embodiment is based on the idea of using the flywheel, in particular the dual mass flywheel, as a component which is present in any case, in order to advantageously start the internal combustion engine. As a result, the number of parts, the cost, the weight and the space requirement can be kept low.

In a further embodiment of the invention, a hydrodynamic torque converter of a transmission, in particular an automatic transmission, of the motor vehicle is used as the flywheel. It has been found that the hydrodynamic torque converter has a particularly high mass inertia, so that it can be used particularly well as a flywheel for starting the internal combustion engine.

In a further embodiment of the invention, it is provided that the coupling device is closed in a first operating state at a, in particular by means of the electric machine, the first rotational speed of the flywheel. In a second operating state, the coupling device is closed at a, in particular by means of the electric machine and, compared to the first speed higher, second speed of the flywheel. Thus is the second speed an over the first speed excessive speed. Under the effect of the speed is to be understood that the flywheel is driven by the electric machine, whereby the flywheel is brought by the electric machine to a respective speed. The said first speed is sufficient, for example, to be able to start the internal combustion engine advantageous. The opposite of the first speed excessive second speed allows the realization of a particularly rapid and thus sporting start of the internal combustion engine, so that, for example, a particularly rapid and athletic start of the motor vehicle is feasible.

In a further embodiment of the invention can be provided that the output shaft is driven as a result of the closing of the coupling device via the flywheel of the electric machine, in particular after the internal combustion engine has been started using the rotational energy stored in the rotating flywheel. This means that the flywheel is arranged relative to a force and / or torque flow from the electric machine via the, in particular closed, coupling device to the output shaft between the electric machine and the output shaft, so provided by the electric machine torques first on the flywheel and then transferred to the coupling device or the output shaft. As a result, the flywheel can be driven particularly efficiently by means of the electric machine or kept at speed.

Finally, it has proved to be particularly advantageous if, as the coupling device, one of a starting element, via which the motor vehicle can be driven by the internal combustion engine, is used different coupling device provided in addition to the starting element. The starting element is, for example, different from the coupling device, provided in addition to the coupling device and designed for example as a friction clutch, by means of which, for example, a transmission of the motor vehicle with the output shaft and / or flywheel coupled and decoupled from the output shaft or the flywheel. Furthermore, it is conceivable that the starting element is the abovementioned hydrodynamic torque converter.

To further develop a drive train specified in the preamble of claim 10 type such that the internal combustion engine, especially after an automatic shutdown of the internal combustion engine, particularly advantageous and fast tempered, that is, can be started, it is inventively provided that the drive train at least one flywheel and at least one coupling device, which between at least one closed position, in which the flywheel via the coupling device ( 13 ) is connected or coupled to the output shaft, and at least one open position is adjustable, in which the flywheel is decoupled from the output shaft. In this case, the flywheel, in particular in terms of their mass and thus formed with respect to their inertia to drive the internal combustion engine due to an adjustment of the clutch device from the open position to the closed position, the output shaft exclusively by means stored in the rotating flywheel rotational energy. Advantages and advantageous embodiments of the method according to the invention are to be regarded as advantages and advantageous embodiments of the drive train according to the invention and vice versa.

Further details emerge from the following description of preferred embodiments with the accompanying drawings. Showing:

1 a schematic representation of a first embodiment of a drive train for a motor vehicle, with an output shaft having an internal combustion engine, and with a flywheel, by means of which for starting the internal combustion engine, the output shaft is driven;

2 a schematic representation of a second embodiment of the drive train; and

3 a diagram illustrating a method for starting the internal combustion engine.

In the figures, the same or functionally identical elements are provided with the same reference numerals.

1 shows in a schematic representation of a first embodiment of the whole with 1 Designated powertrain for a motor vehicle, which is designed for example as a motor vehicle, especially passenger cars. The powertrain 1 includes an internal combustion engine 2 , which is also referred to as an internal combustion engine. The internal combustion engine 2 is designed for example as a diesel engine, gasoline engine or as another internal combustion engine. In the present case is the internal combustion engine 2 designed as a reciprocating engine and includes a cylinder housing 3 through which a plurality of combustion chambers in the form of cylinders 4 is formed.

Furthermore, the internal combustion engine comprises 2 an output shaft which is present as a crankshaft 5 is trained. The crankshaft 5 is on a housing element of the internal combustion engine 2 rotatably mounted about an axis of rotation relative to the housing member. The housing element is for example integral with the cylinder housing 3 educated. Alternatively, it is conceivable that the housing element as separate from the cylinder housing 3 trained and with the cylinder housing 3 connected housing element is formed.

During a fired operation of the internal combustion engine 2 be the cylinders 4 Fuel, especially liquid fuel, and air supplied, so in the respective cylinder 4 a fuel-air mixture is created. This fuel-air mixture is burned, causing the crankshaft 5 driven, that is rotated about its axis of rotation. By driving the crankshaft 5 represents the internal combustion engine 2 in their fired operation torques ready by means of which at least one wheel of the motor vehicle and thus the motor vehicle are driven in total.

Furthermore, the drive train includes 1 a gearbox 6 which can be designed, for example, as an automatic transmission or as a manual transmission, in particular as a manual transmission. As will be explained in more detail below, that of the internal combustion engine 2 over the crankshaft 5 provided torques in the transmission 6 initiated, that is on the transmission 6 be transmitted. This includes the gearbox 6 a transmission input shaft 7 to which the internal combustion engine 2 over the crankshaft 5 provided torques are transferable. About the transmission input shaft 7 can the from the internal combustion engine 2 provided torques in the transmission 6 be initiated. By means of the gearbox 6 Be the over the transmission input shaft 7 in the transmission 6 introduced torques converted, for example, in contrast, higher or lower torques, wherein the transmission 6 the converted torques, for example via a transmission output shaft 8th provides. The of the transmission 6 over the transmission output shaft 8th provided torques are transmitted for example to the aforementioned wheel, in particular to a plurality of wheels of the motor vehicle, whereby the wheel or the wheels and thus the motor vehicle are driven in total. The transmission output shaft 8th is also referred to as output or is part of an output, which related to a torque flow from the transmission 6 on the output after the transmission input shaft 7 is arranged.

The powertrain 1 further comprises an electric machine 9 which is operable for example in a motor operation and thus as an electric motor. In engine operation, the electric machine stops 9 , in particular via a rotor of the electric machine 9 , Torques ready, which can be used.

The powertrain 1 also includes a flywheel 10 on a wave 11 arranged or rotationally fixed to the shaft 11 connected is. The flywheel 10 and the wave 11 are coaxial with the crankshaft 5 arranged and thus rotatable about the aforementioned axis of rotation. At the in 1 shown first embodiment is the flywheel 10 as a flywheel, in particular as a dual mass flywheel (ZMS) formed.

As further out 1 recognizable is the flywheel 10 not in the electric machine 9 integrated, but the flywheel 10 and the electric machine 9 are separately formed, independent components of the powertrain 1 so that, for example, the electric machine 9 disassembled, that is from the drive train 1 could be removed without the flywheel 10 to dismantle or remove. Further, the electric machine 9 desachsiert, so non-coaxial with the flywheel 10 arranged.

Furthermore, the drive train includes 1 a starting element 12 , which is designed as a starting clutch, in particular as a friction clutch. The starting element 12 is adjustable between at least one open state and at least one closed state. In the closed state, the transmission input shaft 7 via the starting element 12 with the wave 11 and thus with the flywheel 10 coupled so that between the transmission input shaft 7 and the wave 11 or the flywheel 10 via the starting element 12 Torques can be transmitted. In the opened state of the starting element 12 is the transmission input shaft 7 from the wave 11 or from the flywheel 10 decoupled, so no torque between the transmission input shaft 7 and the wave 11 or the flywheel 10 via the starting element 12 can be transmitted. In a torque flow from the internal combustion engine 2 over the flywheel 10 to the transmission input shaft 7 is the starting element 12 between the flywheel 10 and the transmission input shaft 7 arranged. In the closed state of the starting element 12 is the momentum 10 for example via the starting element 12 with the over the transmission output shaft 8th coupled drivable wheel. In the opened state of the starting element 12 however, the momentum is 10 decoupled from the wheel.

Furthermore, the powertrain includes 1 a coupling device in the form of a starting clutch 13 , Out 1 it is recognizable that the starting clutch 13 one of the starting element 12 different, in addition to the starting element 12 provided coupling device, wherein the starting clutch 13 is designed for example as a friction clutch. Also the starting clutch 13 is, in particular by means of a in 1 particularly schematically illustrated actuator 14 , Between at least one open state, that is, at least one closed position, and at least one closed state, that is, at least one open position, adjustable. In the open state of the starting clutch 13 is the crankshaft 5 from the wave 11 and thus of the flywheel 10 decoupled, so that in the open state of the starting clutch 13 no torques between the flywheel 10 and the crankshaft 5 over the starting clutch 13 can be transmitted. In the closed state of the starting clutch 13 however, the crankshaft 5 with the wave 11 and thus with the flywheel 10 , in particular rotationally fixed, coupled, so that in the closed state of the starting clutch 13 Torques between the flywheel 10 and the crankshaft 5 over the starting clutch 13 can be transmitted. The actor 14 is, for example, an electric or electrically operable, a hydraulic or hydraulic operable or a pneumatic or pneumatically operable actuator, so that the starting clutch 13 for example, is electrically or pneumatically or hydraulically adjustable between the open state and the closed state.

The powertrain 1 further comprises an electronic computing device 15 , which is also referred to as a control unit. The actor 14 is controlled by the control unit, so that the actuator 14 by means of the control device (electronic computing device 15 ), in particular regulated or controlled, can be. This allows the starting clutch 13 by means of the control unit via the actuator 14 be adjusted between the open state and the closed state, in particular automatically, so that a need-based adjustment of the starting clutch 13 can be displayed between the closed state and the open state.

The electric machine 9 , the flywheel 10 , the starting clutch 13 and the actor 14 are, for example, components of a whole with 16 designated starter device, by means of which the internal combustion engine 2 in the manner described below, particularly quickly started, that is, can be started. This means that the starter device 16 for carrying out a method for starting the internal combustion engine 2 is being used. In an unfired operation run in the cylinders 4 that is in the internal combustion engine 2 , no combustion processes, by means of which the crankshaft 5 could be driven. To the internal combustion engine 2 to start or to start, that is, to transfer from the unfired operation to the fired operation, becomes the crankshaft 5 driven and thereby to a sufficient speed, in particular starting speed, brought up in the cylinders 4 or in the internal combustion engine 2 Burning processes can proceed by means of which the crankshaft 5 then, in particular without the aid of the starter device 16 , driven, that is to say can be rotated about its axis of rotation.

In the context of the aforementioned method, the crankshaft 5 over the starting clutch 13 Coupled with the flywheel by means of the actuator 14 the initially opened starting clutch 13 - especially if the flywheel 10 turns - is closed, thereby starting the internal combustion engine 2 the crankshaft 5 exclusively by means of the rotating or rotating flywheel 10 to drive stored rotational energy. Thus omitted for starting the internal combustion engine 2 a torque flux from the electric machine 9 on the drive shaft 5 , In other words, to start the internal combustion engine 2 the crankshaft 5 without further connection of an electric motor generated and on the crankshaft 5 transmitted torque started.

In particular, in the method, a first step is provided in which the flywheel 10 by means of the electric machine 9 , in particular in its engine operation, is driven while the starting clutch 13 open, causing at least the flywheel 10 , in particular the flywheel 10 and the electric machine 9 , from the crankshaft 5 is decoupled or are. This means that in the first step, the flywheel 10 by means of the electric machine 9 driven, that is rotated about the axis of rotation, while the at least flywheel 10 from the crankshaft 5 is decoupled. This will cause the crankshaft 5 not in the first step of the flywheel 10 or from the electric machine 9 driven. For example, in a second step of the method subsequent to the first step in time, the starting clutch is activated 13 by means of the actuator 14 closed, causing the crankshaft 5 at least with the flywheel 10 is coupled.

As a result of closing the starting clutch 13 is the crankshaft 5 at least with the flywheel 10 connected and thus at least, in particular exclusively, from the flywheel 10 driven and thereby, for example, accelerated and thus brought to a sufficiently high speed, which for starting the internal combustion engine 2 that is, sufficient to perform the fired operation. Since only the flywheel 10 for driving the crankshaft 5 is used, the electric machine 9 be designed particularly space and weight.

As a result of closing the starting clutch 13 is the crankshaft 5 over the starting clutch 13 with the flywheel 10 connected, so in the rotating flywheel 10 stored rotational energy or kinetic energy and thus torques of the flywheel 10 on the crankshaft 5 be transmitted. This will cause the crankshaft 5 , in particular exclusively, of the flywheel 10 driven and, for example, brought to a sufficiently high speed for the fired operation. At the in 1 shown first embodiment, it is provided that the flywheel 10 with the electric machine 9 , in particular rotationally fixed, is coupled.

In the first embodiment, for example, a belt drive 17 with a wrapping element 18 provided, the electric machine 9 over the belt drive 17 with the flywheel 10 is coupled. The belt drive 17 is designed for example as a belt drive or chain drive, so that as an endless drive means, in particular traction means, trained wrap 18 is designed as a belt or chain. About the belt drive 17 can torques from the electric machine 9 on the flywheel 10 be transmitted, causing the flywheel 10 over the belt drive 17 from the electric machine 9 can be driven. Instead of the belt drive 17 Other coupling devices are conceivable over which the flywheel 10 with the electric machine 9 coupled or can be coupled.

Basic idea of the powertrain 1 is, the internal combustion engine 2 over the rotating flywheel 10 , that is exclusively using in the rotating flywheel 10 stored kinetic energy to start. The method or the starter device 16 Can be used with manual transmissions as well as with automatic transmissions or other transmissions. In particular, in a manual transmission is called the flywheel 10 used a dual mass flywheel (DMF), which in this case as part of the internal combustion engine 2 and the transmission 6 is installed. The flywheel 10 is used as a flywheel to the crankshaft 5 in a particularly short time, that is to bring particularly fast to a sufficiently high speed, so that the internal combustion engine 2 can be started very quickly. Present is the flywheel 10 between the starting clutch 13 and the starting element designed as a starting clutch 12 arranged. There by means of the starter device 16 the crankshaft 5 Speeds up quickly and quickly and can be brought to speed, the starter device 16 also known as instant-boost or instant-boost system. Preferably, it is provided that the electrical machine 9 with the flywheel 10 about the present as Umschlingungstrieb 17 trained coupling device with one of 1 different translation is coupled. The starter device 16 is space-saving designed as a module disc and can without excessive design effort between the gearbox 6 and the internal combustion engine 2 to get integrated. Preferably, the starter device is a module element 16 Flanged and bolted directly on the engine side or on the gearbox side. In other words, the starter device 16 for example, to the internal combustion engine 2 , in particular to the housing element of the internal combustion engine 2 , and / or to the transmission 6 , in particular to the housing element of the transmission 6 , directly flanged and preferably screwed.

2 shows a second embodiment of the drive train 1 , The second embodiment differs in particular from the first embodiment that the transmission 6 is designed as an automatic transmission and as a starting element 12 a hydrodynamic torque converter, which in the second embodiment as the flywheel 10 is being used. In the second embodiment, the powertrain includes 1 one of the starting element 12 and from the starting clutch 13 different, additionally provided second coupling device iAE, which in a torque flow of the starting element 12 to the about the transmission output shaft 8th drivable wheel between the starting element 12 and the wheel or the transmission output shaft 8th , in particular between the flywheel 10 and the wheel or the transmission output shaft 8th , is arranged.

Analogous to the starting element 12 and to the starting clutch 13 is the coupling device iAE adjustable between at least one closed state or a closed position and at least one open state or an open position. In the closed position is the flywheel 10 via the coupling device iAE with the transmission output shaft 8th and thus coupled with the wheel. In the open position, however is the momentum 10 from the transmission output shaft 8th and thus decoupled from the wheel.

The starter device 16 is used in the second embodiment for an automatic transmission. In this case, the hydrodynamic torque converter is a core component of the transmission 6 and acts, in particular in a closed state of the hydrodynamic torque converter, as the flywheel 10 , For example, the closed state of the hydrodynamic torque converter is understood to mean that a torque converter lockup clutch of the hydrodynamic torque converter is closed. In contrast to the manual transmission provided in the first embodiment 6 deleted in the second embodiment due to the operation of the automatic transmission, for example, designed as a friction clutch starting clutch.

In the second embodiment, the electric machine 9 For example, a higher performance than in the first embodiment, since the hydrodynamic torque converter in comparison to the dual mass flywheel has a larger moment of inertia. Due to the inertia of the hydrodynamic torque converter and due to drag torques of the gearbox 6 is the electric machine 9 for example, designed for automatic transmission higher or more powerful than for manual transmission. Basic is the starter setup 16 applicable for all engines, cylinder numbers and gear types. Before and in the following, the function of the starter device will be described 16 , as described, explained for manual transmission and automatic transmission.

3 shows a diagram on the abscissa 19 the time is up. On the basis of in the 3 the diagram shown is the method for starting the internal combustion engine 2 explained in more detail. For example, the method is carried out in combination with a start-stop automatic system, by means of which, in particular via the control unit, the internal combustion engine 2 automatically switched off and then automatically started, that is started, is. In the in 3 Diagram shown are three gradients n _J , n _VM and V _Fzg registered. The curve n _J illustrates the speed of the flywheel 10 over time, where the curve n _{VM is} the speed of the internal combustion engine 2 , in particular the crankshaft 5 , illustrated over time. Furthermore, the course v _{Fzg illustrates} the speed of the motor vehicle over time. Furthermore, in 3 a traffic signal system 20 which controls the traffic flow on a roadway along which the motor vehicle is moved by the driver. The traffic signal system 20 is also called a traffic light. The driver and thus the motor vehicle approach, for example, the traffic light initially as part of a cruise 21 ,

If, for example, the driver recognizes that the traffic light is red, the driver brakes the motor vehicle in such a way that the motor vehicle comes to a standstill. Thus closes to the constant drive 21 a delay phase 22 of the motor vehicle. This is done in the context of a first phase 23 a so-called dropping the internal combustion engine 2 , As part of this dropping an automatic shutdown of the internal combustion engine is after a certain requirement such as after falling below a certain speed and / or after pressing a clutch pedal 2 , in particular by means of the control unit, activated and thus, for example, the starting element 12 open. Depending on the gear, the starting element 12 either by the driver manually via a switching element (manual transmission) or software-controlled via the control unit (automatic transmission) opened. In particular, in the automatic transmission, it is provided to open the clutch device iAE, wherein the clutch device iAE example, by means of the control device, in particular automatically, open, that is from its closed state (closed position) in its open state (open position) is adjusted.

By opening the starting element 12 or the lockup clutch becomes the internal combustion engine 2 at a certain time from the gearbox 6 , in particular of the transmission input shaft 7 , or from the output, in particular from the drivable wheel, separated so that the internal combustion engine 2 is not undesirably strangled. By opening the starting element 12 or the coupling device iAE is also the flywheel 10 separated from the wheel, so that the rotating flywheel 10 not or at least not overly slowed down.

In the first phase, for example, parallel to the starting clutch 13 also open and the internal combustion engine 2 is automatically switched off, so that also referred to as engine speed speed of the internal combustion engine 2 , in particular the crankshaft 5 , drops to 0. By opening the starting element 12 or the coupling device iAE is the flywheel 10 from the transmission output shaft 8th decoupled, with the transmission output shaft 8th an output shaft is, which is also referred to as output. By opening the starting element 12 or the coupling device iAE can the flywheel 10 rotate at least substantially free, so that a particularly high rotational energy in the rotating flywheel 10 is stored.

To the first phase 23 closes a second phase 24 of the method, wherein the second phase 24 a so-called maintenance phase is. Out 3 It can be seen that in the first phase 23 subsequent, second phase 24 that is after the starting clutch 13 was opened, the speed of the flywheel 10 not or only slightly decreases, as the flywheel 10 before opening the starting clutch 13 from the crankshaft 5 was driven, with the flywheel 10 due to its high inertia even after opening the starting clutch 13 and after opening the starting element 12 or the clutch device iAE at least substantially retains its speed or only slightly reduced. By opening the starting clutch 13 is the momentum 10 from the internal combustion engine 2 , in particular of the crankshaft 5 , decoupled. Furthermore, the flywheel is 2 from the transmission input shaft 7 or from the output, in particular from the transmission output shaft 8th , decoupled, since the starting element 12 or the coupling device iAE was also opened. Through this decoupling of the flywheel 10 from the internal combustion engine 2 and from the output, the flywheel can 10 at least essentially free to turn. To overcome frictional forces and to further drive the flywheel 10 becomes the flywheel 10 during the second phase 24 from the electric machine 9 driven, with the flywheel 10 for example, with the electric machine 9 is coupled or is. The electric machine 9 is thus for a basic speed of the flywheel 10 responsible and can even increase the speed of the flywheel in the best case 10 compared to one before opening the starting clutch 13 take place.

In this context, it is possible to significantly increase the driving dynamics of the motor vehicle, because the electric machine 9 can the speed of the flywheel 10 increase so much that, if desired, a particularly dynamic start-up is possible. In this case, certain starting states are brought into harmony with a respective driving mode (eco, comfort, sport) and, at the driver's discretion, for example, set, in particular controlled, via a switch or via an operating element. In this context, for example, when activated sport mode, the speed of the flywheel 10 correspondingly higher than in Comfort or Eco mode, in order to subsequently couple the flywheel 10 with the crankshaft 5 to achieve an increased synchronous speed. Thus, a boost effect by an overshoot of the speed of the internal combustion engine 2 reached.

To the second phase 24 closes a third phase 25 which is also called the start phase. As part of the starting phase, the starting or starting the internal combustion engine takes place 2 , After the switch-on request, the starting clutch becomes 13 closed, especially during the starting element 12 or the coupling device iAE is still open. By a force or frictional connection when starting the speed of the flywheel 10 with the speed of the crankshaft 5 synchronized. Thus, the speed of the crankshaft increases 5 from 0 to the synchronous speed. As a result, an ignition for igniting the respective fuel-air mixture is released and the starting or starting is completed. At one of the third phase 25 subsequent, fourth phase 26 a starting process of the motor vehicle takes place. This starting process takes place via the starting element 12 or the coupling device iAE. When the starting element 12 or the coupling device iAE and the starting clutch 13 are closed, for example, when accelerating the crankshaft 5 and thus the motor vehicle and the flywheel 10 accelerates, for example, in one of the fourth phase 26 subsequent acceleration phase 27 he follows. Further, the wheel of the motor vehicle on the transmission output shaft 8th driven. To the acceleration phase 27 then joins one again 28 designated Constantfahrt on.

The starting of the internal combustion engine 2 by means of the starter device 16 has in particular the following advantage: angular momentum conservation, whereby by the use of the flywheel mass 10 as a hub no external moment acts, which is at engine bearings for storing the internal combustion engine 2 supported; by using an internal moment and a torque compensation no tumbling of the internal combustion engine takes place 2 so that the internal combustion engine 2 can be started or started without starting shaking; Vibration loads can be kept particularly low, so that a comfort behavior for occupants of the motor vehicle is improved; the starting device 16 is a particularly reflexive system, which allows the realization of short start times, since a torque for starting the internal combustion engine 2 directly applied and no tracking of a pinion starter is required; improved response, especially in so-called change-of-mind situations in which the internal combustion engine 2 is restarted automatically a short time after initiating an automatic shutdown; low load on a vehicle electrical system of the motor vehicle when starting the internal combustion engine 2 because the energy to start the Internal combustion engine 2 at least substantially or exclusively of the flywheel 10 provided; Modular construction of the starter device 16 so that a particularly simple integration of the internal combustion engine and the transmission 6 can be realized without additional flange constructions and novel fittings, so that the starter device 16 can be integrated directly into existing systems; the method by the starter device 16 are applicable to all engines with different numbers of cylinders and types of transmissions; Starting or entry speeds are adjustable for different driving modes.

LIST OF REFERENCE NUMBERS

1

powertrain

2

Internal combustion engine

3

cylinder housing

4

cylinder

5

crankshaft

6

transmission

7

Transmission input shaft

8th

Transmission output shaft

9

electric machine

10

Inertia

11

wave

12

starting element

13

starting clutch

14

actuator

15

electronic computing device

16

starter device

17

belt drive

18

wrapping

19

abscissa

20

Traffic signal

21

constant travel

22

deceleration phase

23

first phase

24

second phase

25

third phase

26

fourth phase

27

acceleration phase

28

constant travel

prs

coupling device

_ny

 rotation speed

n _VM

rotation speed

v _vehicle

rotation speed

QUOTES INCLUDE IN THE DESCRIPTION

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

Cited patent literature

• DE 102009008599 A1 [0004]
• WO 2010/130058 A1 [0004]
• DE 102010012514 A1 [0004]
• DE 2943554 A1 [0004]
• DE 102010054287 A1 [0004]

Claims (10)

Method for starting an output shaft ( 5 ) having internal combustion engine ( 2 ) of a motor vehicle, in which for starting the internal combustion engine ( 2 ) the output shaft ( 5 ), characterized in that the output shaft ( 5 ) via a coupling device ( 13 ) with a flywheel ( 10 ) is coupled by means of an actuator ( 14 ) the initially opened coupling device ( 13 ) is closed, thereby to start the internal combustion engine ( 2 ) the output shaft ( 5 ) exclusively by means of the rotating flywheel ( 10 ) to drive stored rotational energy. Method according to claim 1, characterized by the steps: - driving the flywheel ( 10 ) by means of an electric machine ( 9 ), while the coupling device ( 13 ) is opened, whereby at least the flywheel ( 10 ) from the output shaft ( 5 ) is decoupled; and closing the coupling device ( 13 ) by means of the actuator ( 14 ), whereby the output shaft ( 5 ) via the coupling device ( 13 ) at least with the flywheel ( 10 ) is coupled. A method according to claim 2, characterized in that the flywheel ( 10 ) after closing the coupling device ( 13 ) at least temporarily by means of the electric machine ( 9 ) are driven while the coupling device ( 13 ) closed is. Method according to one of the preceding claims, characterized in that the closing of the coupling device ( 13 ) by means of an electronic computing device ( 15 ) of the motor vehicle is effected. Method according to one of the preceding claims, characterized in that the coupling device ( 13 ) is closed when the flywheel ( 10 ) has a predetermined speed. Method according to one of the preceding claims, characterized in that as the flywheel ( 10 ) A flywheel, in particular a dual mass flywheel, is used. Method according to one of the preceding claims, characterized in that as the flywheel ( 10 ) a hydrodynamic torque converter ( 12 ) of a transmission ( 6 ) of the motor vehicle is used. Method according to one of the preceding claims, characterized in that the coupling device ( 13 ) in a first operating state at a first rotational speed of the flywheel ( 10 ) and in a second operating state at a second speed of the flywheel ( 10 ) is closed. Method according to one of the preceding claims, characterized in that the output shaft ( 5 ) due to the closing of the coupling device ( 13 ) at least temporarily via the flywheel ( 9 ) of the electric machine ( 9 ) is driven. Powertrain ( 1 ) for a motor vehicle, with an output shaft ( 5 ) having internal combustion engine ( 2 ), characterized by: - at least one inertial mass ( 10 ); and at least one coupling device ( 13 ), which between at least one closed position in which the flywheel ( 10 ) via the coupling device ( 13 ) with the output shaft ( 5 ) is connected, and at least one open position is adjustable, in which the flywheel ( 10 ) from the output shaft ( 5 ) is decoupled, the flywheel ( 10 ) is adapted to start the internal combustion engine ( 2 ) as a result of an adjustment of the coupling device ( 13 ) from the open position into the closed position, the output shaft ( 5 ) exclusively by means of the rotating flywheel ( 10 ) to drive stored rotational energy.

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