DE102015215550A1 - Method for starting an internal combustion engine of a motor vehicle - Google Patents

Abstract

The invention relates to a method for starting an internal combustion engine (105) with a belt-driven starter generator (130) and a pinion starter (110), wherein the internal combustion engine (105) has a crankshaft (151) which is torque-transmitting with the belt-driven starter generator (130) and the A pinion starter (110) is connectable, wherein from the belt-driven starter generator (130) a biasing moment (Mvor1, Mvor2) on the crankshaft (151) is generated (202, 502), which is less than a breakaway torque of the crankshaft (151) the pinion starter (110) alone or the pinion starter (110) and the belt-driven starter generator (130) together generate a starting torque on the crankshaft (151) that is at least as large as the breakaway torque of the crankshaft (151), wherein the crankshaft (151) is rotated by the starting torque (207, 512, 523).

Description

The present invention relates to a method for starting an internal combustion engine of a motor vehicle as well as a computer unit and a computer program for its implementation.

State of the art

Electric machines can be used in motor vehicles as so-called starter generators, on the one hand to start the engine during engine operation of the electric machine and on the other hand to generate power for the electrical system and for charging the motor vehicle battery in the generator mode of the electric machine. Starter generators can be connected via a belt drive with the internal combustion engine or its crankshaft.

For the use as belt-driven starter generators (RSG) are particularly foreign-excited three-phase synchronous machines, since their motor torque is particularly easy to control. A desired torque can be adjusted by appropriately driving the rotor winding (excitation coil) and / or the stator winding (for example, three or five stator phases are common). A temporal modulation of the torque may be preferred in order to achieve as low a noise and low-vibration starting operation as possible.

To start the internal combustion engine, the drive torque of the starter generator is transmitted via the belt to the crankshaft of the internal combustion engine to accelerate the crankshaft to a minimum speed. When the minimum speed is reached, an ignitable mixture is ignited in the combustion chamber at a defined time.

To start the engine, a breakaway torque must be overcome, which can be very large, especially during cold starts. Therefore, powerful starter generators must be used. At very low temperatures, the starter generator can reach its power limit. To avoid this, a conventional pinion starter can be used in particular for the cold start to support the starter generator or alternatively.

The DE 10 2012 203 374 A1 describes a method of pretensioning the belt prior to starting, wherein the starter generator builds up torque gradually rather than jerkily. A pinion starter is not used there.

Disclosure of the invention

According to the invention, a method for starting an internal combustion engine of a motor vehicle as well as a computing unit and a computer program for carrying it out with the features of the independent patent claims are proposed. Advantageous embodiments are the subject of the dependent claims and the following description.

The internal combustion engine has a belt-driven starter generator and a pinion starter. Pinion starter and starter generator may e.g. be installed in a common housing. In the course of starting the internal combustion engine, a biasing torque is generated by the belt-driven starter generator, which is lower than a breakaway torque of the internal combustion engine. However, this biasing torque is sufficient to bias the belt.

After the preload torque has been introduced into the belt drive, a starting torque is generated by the sprocket starter alone or in the course of a so-called combination start by the sprocket starter and the belt-driven starter generator in the course of a so-called sprocket start. This starting torque is at least as large as the breakaway torque of the internal combustion engine. The starting torque is transmitted to the crankshaft of the internal combustion engine, whereby the crankshaft is set in rotary motion and the internal combustion engine starts. After breaking away, if desired, the moment can be further increased.

Basically, especially during warm starts, e.g. a start / stop operation, the starting torque can be generated in particular only by the belt-driven starter generator (so-called RSG start).

The belt-driven starter generator is connected to the crankshaft of the engine via a belt (e.g., V-ribbed belt). In this belt drive (secondary drive), in addition to the belt-driven starter generator, further components may be connected to the belt, e.g. Fans or coolant pumps.

As a starter Ritzel is in particular a starter of the internal combustion engine to understand, which is designed in particular as an electric machine with upstream planetary or spur gear and a release device. A starter pinion driven by the electric machine can be meshed with a ring gear on the crankshaft of the internal combustion engine. If the pinion is sufficiently far in the ring gear, the rotor of the electric machine begins to rotate, whereby torque is transmitted to the internal combustion engine via the starter pinion. This then turns off and finally starts.

In particular, a belt tensioner is further provided to tension the belt, such as a pendulum belt tensioner or two-arm tensioner. A position of the belt tensioner or its pendulum arms can change in particular in the direction of a tensioned or shortened run of the belt.

Due to the biasing torque generated, the internal combustion engine or the crankshaft is not yet set in rotary motion. However, the strap of the belt drive, in this case in particular the load strand with respect to the starting process (referred to below as the starting load line), can be prestressed by the prestressing moment produced. By virtue of the method, forces and stresses which act on the belt and the components connected thereto and on the crankshaft when the internal combustion engine is started can be kept as low as possible. The lifetimes of the belt-driven starter generator and the other components of the belt drive can thus be increased. Furthermore, the starting process by the method can be carried out quietly and with great comfort.

When the internal combustion engine is deactivated and when no torque is applied in the belt drive, the belt and in particular the belt tensioner is in a rest position. The load span and slack side of the belt relative to a motorized operation of the RSG have the same tension. In a conventional sprocket start, when the pinion starter applies torque to the crankshaft and breaks it, the load train is extended relative to the engine operation of the RSG (hereinafter referred to as the motorized load RGG) and the idleness related to the engine operation of the RSG (FIG. in the following referred to as motor RSG empty strand) shortened or tensioned. Until the motorized RSG slack side is fully tensioned, the crankshaft turns at a certain speed. When the engine RSG slip is sufficiently tensioned and the engine transmits a sufficiently large torque to the belt-driven starter generator to overcome its comparatively high (rotational) inertia, the belt-driven starter generator (or its rotor) is set in rotational motion. The belt-driven starter generator and the other components of the belt drive are thereby accelerated comparatively strong, which can be regarded as a shock process. Large forces or high loads act on the belt-driven starter generator and the belt as well as on the other components of the belt drive.

In the case of a combination starter, the crankshaft is released by the meshed pinion starter, thereby initially lengthening or relaxing the motorized RSG load space. In such a Kombistart of the belt-driven starter generator is then generated in addition to the moment of the pinion starter high torque to accelerate the engine quickly. The previously relaxed strand is now stretched accordingly strong. Here, large forces and high loads act on the belt and the other components of the belt drive.

As a result of the generated prestressing torque in the course of the method for starting the internal combustion engine, such high loads and high accelerations of belt, belt-driven starter generator and the further belt drive components can be reduced. Shock and load peaks can be avoided. In particular, by the biasing moment, in particular, the startup load space, i. with sprocket start the motorized RSG empty section and with Kombistart the motorized RSG load section, respectively shortened or tensioned, before the crankshaft breaks loose. Subsequently, the starting moment required for starting the internal combustion engine is generated by the pinion starter, possibly in combination with the belt-driven starter generator.

According to a preferred embodiment of the method, a pinion start of the internal combustion engine is performed. The starting torque is generated solely by the pinion starter. In this case, a braking torque is advantageously generated by the belt-driven starter generator as a prestressing torque. In this context, a braking torque is to be understood as meaning a torque which counteracts the direction of rotation of the crankshaft or which counteracts a torque of the pinion starter.

The pinion start can be carried out, for example, if, due to various boundary conditions, starting with the belt-driven starter generator would not be possible, for example because of too low a current output of a corresponding battery or because of a limited torque of the belt-driven starter generator.

The biasing moment is in particular below what the belt-driven starter generator is able to deliver in the light of the present boundary conditions. In particular, the starting load is shortened or biased by the biasing torque and the belt tensioner pivots in particular in the direction of the starting load. As soon as the starting load is sufficiently biased, the pinion start is initiated. The starting load remains in particular biased at least until the crankshaft breaks. Size Accelerations and load peaks in the belt drive are thus avoided.

Advantageously, the biasing torque is no longer generated or turned off after the crankshaft is broken by the starting torque generated by the pinion starter. Thus, it can be prevented that the braking biasing torque of the rotating crankshaft counteracts and slows down the start of the internal combustion engine unnecessarily or obstructed. For example, the shutdown of the biasing torque may be arranged by a higher-level control device (e.g., engine control unit), for example, by a corresponding torque (zero) default to the belt-driven starter generator.

Preferably, the shutdown of the biasing torque can also be implemented as an independent function in the belt-driven starter generator or in its control unit. For this purpose, a rotational movement of the internal combustion engine and / or of the belt-driven starter generator is preferably detected by the latter itself and the torque generation is terminated immediately after detection.

According to another advantageous embodiment of the method, a Kombistart the internal combustion engine is performed. The starting torque is generated in this case by the pinion starter and the belt-driven starter generator together. Advantageously, a driving torque is generated by the belt-driven starter generator as a prestressing torque. As a driving moment in this context, a torque to understand, which acts in the direction of rotation of the crankshaft and which supports a torque of the pinion starter.

Also by this driving biasing moment, the starting load can be biased or shortened before the crankshaft breaks. The belt tensioner swings especially in the direction of the starting load. The crankshaft is still at rest, the starter pinion can be in the standing sprocket of the crankshaft. Preferably, as soon as the meshed starter pinion of the pinion starter starts to rotate and generates torque, the driving torque generated by the belt-driven starter generator is increased. Alternatively, it is also advantageous that the belt-driven starter generator increases the biasing torque only when the internal combustion engine breaks down. The increase in bias torque may be triggered by a higher-level controller (e.g., engine controller) or by the belt-driven starter generator controller.

The starting load is thus already sufficiently stretched when the belt-driven starter generator and the pinion starter, a sufficiently large starting torque for breaking the crankshaft is generated. Even in this case, large accelerations and load peaks in the belt drive can thus be avoided.

An arithmetic unit according to the invention, e.g. a control device of a motor vehicle is, in particular programmatically, configured to perform a method according to the invention.

Also, the implementation of the method in the form of a computer program is advantageous because this causes very low costs, especially if an executive controller is still used for other tasks and therefore already exists. Suitable data carriers for providing the computer program are in particular magnetic, optical and electrical memories, such as e.g. Hard drives, flash memory, EEPROMs, DVDs, etc. It is also possible to download a program via computer networks (Internet, intranet, etc.).

Further advantages and embodiments of the invention will become apparent from the description and the accompanying drawings.

The invention is illustrated schematically by means of embodiments in the drawing and will be described below with reference to the drawing.

Brief description of the drawings

1 schematically shows an arrangement of an internal combustion engine, a belt drive, a belt-driven starter generator and a pinion starter, as the invention may underlie.

2 schematically shows a preferred embodiment of the method according to the invention as a block diagram.

3 schematically shows the arrangement 1 when starting the internal combustion engine according to the embodiment of the method according to the invention 2 ,

4 schematically shows a diagram of a belt force of a belt drive of a motor vehicle plotted against time.

5 schematically shows a further preferred embodiment of the method according to the invention as a block diagram.

6 schematically shows the arrangement 1 when starting the internal combustion engine according to the embodiment of the method according to the invention 5 ,

Embodiment (s) of the invention

In 1 is a schematic arrangement 100 from an internal combustion engine 105 of a motor vehicle, a belt-driven starter generator (RSG) 130 , a pinion starter 110 and a belt drive connecting said elements, as may be the basis of the invention.

The internal combustion engine 105 of the motor vehicle has a crankshaft 151 on, the non-rotatable with a crankshaft drive wheel 150 connected is. The crankshaft drive wheel 150 is designed for example as a pulley. Furthermore, the crankshaft 151 in particular rotatably connected to a sprocket (not shown).

The pinion starter 110 For example, an electric motor and a starter pinion 111 exhibit. The starter pinion 111 can be in the sprocket on the crankshaft 151 be meshed or indented. For this purpose, for example, starter relay and lever can be provided. Is the starter pinion 111 sufficiently far in the ring gear, can be a rotor of the electric motor of the pinion starter 110 be set in rotational motion and a torque to the crankshaft 151 transfer.

About a belt 120 , for example via a V-ribbed belt, is the crankshaft drive wheel 150 with the RSG 130 connected torque transmitting. The belt 120 engages in particular non-positively and / or positively in the crankshaft drive wheel 150 and in a drive wheel 131 of the RSG 130 one. The drive wheel 131 is non-rotatable with a rotor of the RSG 130 connected. The internal combustion engine 105 can over the belt 120 with other components 160 , such as fans, air conditioning compressors or coolant pumps, be connected.

The RSG can be operated both motorically and generically. The belt 120 must therefore be able to transmit torque in both directions. The belt is therefore designed, for example, as a V-ribbed belt. Depending on whether the starter generator 130 operated by a motor or generator, change the load side and slack side of the belt 120 , In the engine (the internal combustion engine driving) operation of the starter generator 130 forms a belt section 121 the motorized RSG load strand and a belt section 122 the motoric RSG-leertrum.

Furthermore, a corresponding belt tensioner 140 provided to the belt 120 to stretch. The belt tensioner 140 For example, it may be formed as a pendulum belt tensioner, for example, two pendulum arms 141 and 141b includes, which in particular via a spring mechanism 143 connected to each other. Rotary axes of these two pendulum arms 141 and 141b For example, they are collinear with a rotation axis 132 of the drive wheel 131 of the starter generator 130 , Other embodiments of pendulum belt tensioners or two-arm tensioners with non-collinear axes of rotation of the starter are also possible. This rotation axis 132 of the drive wheel 131 thus simultaneously represents a rotation axis of the pendulum belt tensioner 120 dar. Each pendulum 141 respectively. 141b is each with a tensioner 142a respectively. 142b connected.

The internal combustion engine 105 is in 1 shown in their deactivated state. belt 120 and pendulum belt tensioner 140 is located in a respective rest position or middle position and are not deflected in each case.

A control unit 170 (Engine control unit) is in particular for controlling the internal combustion engine 105 , the sprocket starter 110 and the starter generator 130 set up. The control unit 170 is particularly adapted to the internal combustion engine 105 to start. For this purpose, the control unit 170 adapted to carry out a preferred embodiment of a method according to the invention.

A preferred embodiment of the method according to the invention is in 2 schematically illustrated as a block diagram. In 3 is the arrangement 100 when starting the internal combustion engine 105 according to this preferred embodiment of the method according to the invention shown schematically.

In the course of this preferred embodiment, a pinion start of the internal combustion engine 105 carried out. In step 201 a start request is made, for example by actuating an ignition key or start button of the motor vehicle. In step 202 is from the RSG 130 a braking moment M _{vor1 generated} as a biasing moment. This braking moment M _vor1 acts opposite to the direction of rotation 152 the crankshaft 151 the internal combustion engine 105 ,

The preload torque is less than a breakaway torque of the crankshaft 151 , For example, the preload torque may have a value of 2 Nm. The crankshaft 151 is thus not yet set in rotational motion by the generated biasing moment. However, is generated by the Preload moment in step 203 the belt 120 curious; excited. In particular, the motor RSG is empty 122 tensioned or shortened as take-off load trum, and the motorized RSG loadtrum 121 relaxed as start-up Leertrum or extended. The position of the pendulum belt tensioner changes 140 and the belt 120 , The arms of the pendulum belt tensioner 140 turn around the axis of rotation 132 by the angle φ ₁ in the direction of the starting load.

As soon as the startup load space is sufficiently tensioned, in step 204 the starter pinion 111 meshed with the ring gear on the crankshaft. In step 205 sets the electric motor of the pinion starter 110 the meshed starter pinion 111 in rotational motion and from the pinion starter 110 a starting torque is generated, which is greater than the breakaway torque of the crankshaft 151 is. The crankshaft 151 then breaks loose and the internal combustion engine 105 is set in rotary motion. Once the crankshaft has broken loose, it will step in 206 the biasing _moment M _vor1 off. The internal combustion engine 105 stays in rotation and starts in step 207 ,

By the tensioning of the start-up Lasttrums by means of the generated biasing torque M _before loads and forces in the belt drive 100 be reduced. In 4 is a schematic diagram of the belt force F plotted against time t.

Curve 401 describes a force curve of the belt force during a conventional sprocket start, without a biasing torque is generated. Curve 402 describes a force curve of the belt force in the course of the preferred embodiment of the inventive method described above. F ₀ is a static belt force in an idling of the internal combustion engine 105 ,

As in 4 can be seen occur in conventional pinion start according to curve 401 much larger forces or force peaks, as in the method for starting the internal combustion engine according to curve 402 , By generating the preload torque can on the belt drive 100 At startup forces acting to be reduced. The belt 120 , the starter generator 130 as well as the remaining components 160 are not accelerated as much as in the conventional case. Shock processes and load or force peaks can be avoided or at least reduced.

A further preferred embodiment of the method according to the invention is disclosed in 5 schematically illustrated as a block diagram. In 6 is the arrangement 100 when starting the internal combustion engine 105 shown schematically according to this preferred embodiment.

In the course of this preferred embodiment, a Kombistart the internal combustion engine 105 carried out. In step 501 there is a start request. In step 502 is from the RSG 130 generates a driving moment M _vor2 as a biasing torque, which is lower than the breakaway torque of the crankshaft 151 is. This driving moment M _vor2 acts in particular in the direction of rotation 152 the crankshaft 151 and is for example 2 Nm. The belt 120 is thus in step 503 biased.

The motorized RSG loadtrum 121 in this case also forms the starting load, the motorized RSG slipstream 122 the startup empty run. When preloading the position of the pendulum belt tensioner change 140 and the belt 120 , The arms of the pendulum belt tensioner 140 turn around the axis of rotation 132 by the angle φ ₂ in the direction of the starting load.

As soon as the startup load space is sufficiently tensioned, in step 504 the starter pinion 111 meshed with the ring gear on the crankshaft.

Once the starter pinion 111 can be used immediately, either from the RSG 130 generated moment can be increased. According to step 511 becomes the meshed starter pinion 111 rotated and simultaneously the torque of the RSG 130 elevated. Together generate RSG 130 and pinion starter 110 that to break loose the crankshaft 151 required starting torque. The crankshaft then breaks loose and the internal combustion engine 105 will be in step 512 started.

Once the starter pinion 111 according to step 504 can be used alternatively by the RSG 130 initially, the biasing torque continues to be generated. In step 521 becomes the meshed starter pinion 111 rotated. It is from the pinion starter 110 and the RSG 130 together the moment of inertia on the crankshaft 151 transfer, which is greater than the breakaway torque. In step 522 breaks the crankshaft. Then in step 523 that of the RSG 130 generated moment increased. Together generate RSG 130 and pinion starter 110 now a larger acceleration torque to start the engine 105 , The internal combustion engine 105 will be started.

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 102012203374 A1 [0006]

Claims (11)

Method for starting an internal combustion engine ( 105 ) with a belt-driven starter generator ( 130 ) and a pinion starter ( 110 ), wherein the internal combustion engine ( 105 ) a crankshaft ( 151 ), the torque transmitting with the belt-driven starter generator ( 130 ) and the pinion starter ( 110 ), wherein - of the belt-driven starter generator ( 130 ) a biasing _moment (M _vor1 , M _vor2 ) on the crankshaft ( 151 ) is produced ( 202 . 502 ), which is less than a breakaway torque of the crankshaft ( 151 ), wherein by the pinion starter ( 110 ) alone or by the pinion starter ( 110 ) and the belt-driven starter generator ( 130 ) together a starting torque on the crankshaft ( 151 ) is produced ( 205 . 521 . 522 ), which is at least as large as the breakaway torque of the crankshaft ( 151 ), wherein the crankshaft ( 151 ) is set into rotary motion by the starting moment ( 207 . 512 . 523 ). The method of claim 1, wherein for a pinion start of the belt-driven starter generator ( 130 ) a braking moment (M _vor1 ) as a preload torque on the crankshaft ( 151 ) is produced ( 202 ) and wherein the starting torque of the pinion starter ( 110 ) is generated alone ( 205 ). The method of claim 2, wherein the biasing torque on the crankshaft ( 151 ) is no longer generated ( 206 ), after the crankshaft ( 151 ) was set in rotary motion. Method according to claim 3, wherein a rotational movement of the crankshaft ( 151 ) of the belt-driven starter generator ( 130 ) is detected and wherein upon detection of rotational movement, the biasing torque on the crankshaft ( 151 ) is no longer generated ( 206 ). Method according to one of the preceding claims, wherein for a Kombistart of the belt-driven starter generator ( 130 ) a driving moment (M _vor2 ) as a biasing torque on the crankshaft ( 151 ) is produced ( 502 ) and wherein the starting torque of the pinion starter ( 110 ) and the belt-driven starter generator ( 130 ) is generated together ( 511 . 521 . 522 ). The method of claim 5, wherein the belt-driven starter generator ( 130 ) as long as the biasing _moment (M _vor2 ) on the crankshaft ( 151 ) is generated until the crankshaft ( 151 ) ( 521 ), and that of the belt-driven starter generator ( 130 ) torque is increased after the crankshaft ( 151 ) ( 522 ). The method of claim 5, wherein the belt-driven starter generator ( 130 ) as long as the biasing _moment (M _vor2 ) on the crankshaft ( 151 ) is generated until the pinion starter ( 110 ) generates a torque, and that of the belt-driven starter generator ( 130 ) is increased as soon as the pinion starter ( 110 ) generates a torque ( 511 ). Method according to one of the preceding claims, wherein, by the generated prestressing _moment (M _vor1 , M _vor2 ), a starting load-length of the belt ( 120 ) ( 203 . 503 ). Arithmetic unit ( 170 ), which is adapted to perform a method according to any one of the preceding claims. Computer program comprising a computing unit ( 170 ) to perform a method according to any one of claims 1 to 8, when it on the computing unit ( 170 ) is performed. A machine-readable storage medium having a computer program stored thereon according to claim 10.

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