DE102019206152A1 - Method and control system for operating a powertrain - Google Patents

Abstract

Method for operating a drive train of a motor vehicle with an internal combustion engine (2), a transmission (5), a starting element (8), an engine control unit (9) for controlling the internal combustion engine (2) and with a transmission control unit (10) for controlling the transmission (5), wherein a driver's desired torque (13) is determined for starting and a target starting speed (16) for the internal combustion engine (2) is determined as a function thereof. The engine control unit (9) determines an internal combustion engine component of the torque required by the driver, which the internal combustion engine (2) should provide for starting. The engine control unit (9) determines the target starting speed (16) for the internal combustion engine (2) as a function of the internal combustion engine and provides it to the transmission control unit (10). To start up, the internal combustion engine (2) is torque-controlled by the engine control unit (9) and the starting element (8) is operated by the transmission control unit (10) with differential speed control.

Description

The invention relates to a method for operating a drive train. The invention also relates to a control system for operating a drive train.

A drive train of a motor vehicle has a drive unit and a transmission connected between the drive unit and an output. The gearbox converts speeds and torques and thus provides the tractive power of the drive unit at the output. The drive unit comprises at least one internal combustion engine. In the case of a hybrid vehicle, the drive unit includes an electric machine in addition to the internal combustion engine. The transmission comprises several shifting elements that can be designed as frictional shifting elements or as positive shifting elements. Furthermore, a drive train has a starting element, in particular a starting clutch, which is operated in a slipping manner for the starting process, that is to say with a speed difference. The starting element can be a starting element that is internal to the transmission or that is external to the transmission. In the case of a starting element inside the transmission, a frictional shifting element of the transmission can be used as the starting element.

From the DE 102 02 520 A1 A drive train control for a motor vehicle is known in which a target starting speed for the internal combustion engine is initially determined as a function of characteristic curves for a starting process, the characteristic curve-based target starting speed being modified on the basis of parameters that reflect an actual acceleration behavior of the motor vehicle. With these parameters, the actual acceleration behavior of the motor vehicle. reflect, it is in particular an output speed gradient, the vehicle speed or a speed gradient.

From the DE 10 2006 053 763 A1 It is known to determine a target starting speed for a starting process as a function of a torque desired by the driver.

After DE 10 2006 052 100 A1 the target starting speed for a starting process is determined depending on the air pressure of the ambient air.

From the DE 10 2013 205 798 A1 a further method for controlling a starting process of a motor vehicle is known. In this case, a transmission control unit regulates the internal combustion engine on the one hand and regulates a starting clutch in parallel on the other. To regulate the internal combustion engine, the transmission control unit determines a target starting speed for the internal combustion engine and provides this to the engine control unit.

There is a need to determine the setpoint starting speed for the internal combustion engine of the motor vehicle more precisely for a starting process, specifically in such a way that a torque desired by the driver can be provided.

Proceeding from this, the invention is based on the object of creating a novel method for operating a drive train and a control system for operating a drive train. This object is achieved by a method for operating a drive train according to patent claim 1.

The engine control unit and, in the case of a hybrid vehicle, the engine control unit or hybrid control unit determine an internal combustion engine component of the driver's desired torque, which the internal combustion engine is to provide for starting while providing the driver's desired torque.

The engine control unit and, in the case of a hybrid vehicle, the engine control unit or hybrid control unit also determine the target starting speed for the internal combustion engine and make it available to the transmission control unit as a function of this internal combustion engine component of the driver's desired torque.

To start up, the internal combustion engine is torque-regulated by the engine control unit and the start-up element is operated by the transmission control unit with differential speed control, in such a way that the internal combustion engine provides the internal combustion engine component of the driver's desired torque and that the activation of the starting element controls the internal combustion engine to run up to the target starting speed.

The present invention proposes that the engine control unit and, in the case of a hybrid vehicle, the engine control unit or the hybrid control unit determine the internal combustion engine component of the driver's desired torque that the internal combustion engine should provide for starting while providing the driver's desired torque. The greater the proportion of the driver's desired torque that can be provided via the electric machine in a hybrid vehicle, the lower the internal combustion engine component of the driver's desired torque. Furthermore, the engine control unit and, in the case of a hybrid vehicle, the engine control unit or the hybrid control unit determines the target starting speed as a function of the specific internal combustion engine component of the driver's desired torque, in particular as a function of a torque curve of the Internal combustion engine. The engine control unit and, in the case of a hybrid vehicle, the engine control unit or the hybrid control unit thus provide the determined target starting speed of the internal combustion engine to the transmission control unit. To start up, the internal combustion engine is then torque-controlled by the engine control unit and the starting element is operated by the transmission control unit in a differential speed control. Here, the internal combustion engine provides the internal combustion engine component of the torque requested by the driver. The start-up element controls the acceleration of the internal combustion engine to the set start-up speed.

A particularly advantageous start-up process is possible with the invention.

The target starting speed can be precisely determined by the engine control unit or hybrid control unit. The transmission control unit uses the set starting speed determined in this way to regulate and thus control the starting element. Without the corresponding activation of the starting element, the internal combustion engine operated in the torque control would assume any speed, for example the maximum speed of the internal combustion engine. Only through the interaction of torque control of the internal combustion engine and differential speed control of the starting element is a comfortable starting process achieved.

According to an advantageous development, the target starting speed for the internal combustion engine, which is provided to the transmission control unit by the engine control unit and, in the case of a hybrid vehicle, by the engine control unit or hybrid control unit, is filtered by the transmission control unit while providing a filtered target starting speed. By filtering the target starting speed, driving comfort can be increased when starting off.

According to an advantageous development, in the differential speed control of the starting element, the same is initially controlled by the transmission control unit in such a way that its transmission capacity is initially less than a torque provided on the drive side, so that acceleration of the internal combustion engine to the target starting speed is facilitated. The transmission capacity of the starting element is then increased by the transmission control device in order to reduce a speed difference between a speed on the drive side and a speed on the output side. The start-up element is then completely closed by the transmission control unit. Preferably, if the speed difference at the starting element is less than a limit value, and then if the output-side speed at the starting element is greater than a closing speed threshold, which in turn is lower than the target starting speed for the internal combustion engine, the differential speed-controlled operation of the Starting element terminated by the transmission control unit and the same completely closed. This further development of the invention allows the internal combustion engine to run up comfortably to its setpoint starting speed. The torque that can be transmitted by the starting element is initially less than the torque provided by the drive unit. This makes it easier to run up the engine speed. As soon as no or only a small torque is required to run up the internal combustion engine, the transferable torque of the starting element is raised to the level of the torque provided by the drive unit. Here, slip or the speed difference on the starting element is reduced. At the end of the start-up process, the start-up element is then completely closed. This allows a particularly advantageous and comfortable start-up.

According to an advantageous development, the engine control unit and, in the case of a hybrid vehicle, the engine control unit or hybrid control unit determine the target starting speed for the internal combustion engine as a function of the internal combustion engine component of the driver's desired torque via a torque curve of the internal combustion engine. The torque curve of the internal combustion engine is preferably dependent on an ambient air pressure and / or an ambient temperature. In this way, the target starting speed for the internal combustion engine can be determined particularly advantageously.

The control system according to the invention is defined in claim 7.

• 1 ein Antriebstrangschema eines Kraftfahrzeugs;
• 2 ein Zeitdiagramm zur Verdeutlichung des erfindungsgemäßen Verfahrens zum Betreiben eines Antriebsstrangs eines Kraftfahrzeugs.

Preferred developments emerge from the subclaims and the following description. Embodiments of the invention are explained in more detail with reference to the drawing, without being restricted thereto. It shows:

• 1 a powertrain scheme of a motor vehicle;
• 2 a time diagram to illustrate the method according to the invention for operating a drive train of a motor vehicle.

1 shows a highly schematic drive train diagram of a motor vehicle. The motor vehicle has a drive unit 1 , which at least one internal combustion engine 2 and in the illustrated embodiment of a hybrid vehicle, an additional electrical machine 3 includes. Between the drive unit 1 and a downforce 4th is a gear 5 switched. The gear 5 converts speeds and torques and thus provides the tractive power of the drive unit 1 at the output 4th ready. Between the internal combustion engine 2 and the electric machine 3 is shown in Exemplary embodiment a separating clutch 6th switched. With the separating clutch open 6th is the internal combustion engine 2 disconnected.

According to 1 includes the transmission 5 several switching elements 7th , of which in 1 a switching element 7th is shown as an example. With the switching elements 7th of the transmission 5 it can be frictional shifting elements, such as brakes or clutches, and positive shifting elements, such as claws. Also shows 1 a starting element 8th , which is designed as an internal starting clutch in the illustrated embodiment. Instead of an internal start-up element 8th can also be an external starting element 8th are used. 1 also shows an engine control unit 9 for controlling and / or regulating the operation of the internal combustion engine 2 . Operation of the transmission 5 is controlled by a transmission control unit 10 controlled and / or regulated.

In the case of the in 1 The hybrid vehicle shown is in addition to the engine control unit 9 as well as transmission control unit 10 a hybrid control unit 11 available. The hybrid control unit 11 controls and / or regulates the operation of the electrical machine 3 and in 1 the disconnect clutch 6th .

According to 1 replace the control units 9 , 10 and 11 on the one hand, data from one another and, on the other hand, data with the modules to be controlled and / or regulated.

The present invention relates to a start-up process for such a motor vehicle in which the drive unit 1 at least the internal combustion engine 2 and in the case of a hybrid vehicle, the electric machine as well 3 includes. In the initial state, the vehicle stands still, that is, one speed at the output 4th is zero. The starting element 8th is fully open and the internal combustion engine 2 is operated at its idle speed.

The start-up process is carried out by the driver actuating an accelerator pedal 12th , which is also known as the accelerator pedal, is triggered. Depending on the driver's actuation of the accelerator pedal 12th a torque desired by the driver for the starting process can be determined. The determination of the driver's desired torque depending on the driver's actuation of the accelerator pedal 12th can for example from the transmission control unit 10 or from the engine control unit 9 and in the case of a hybrid vehicle also from the hybrid control unit 11 be made.

According to the invention it is now provided that the engine control unit 9 and in the case of a hybrid vehicle, the engine control unit 9 or the hybrid control unit 11 depending on the driver's desired torque, a combustion engine component of the driver's desired torque determines that the combustion engine 2 for moving off with provision of the torque requested by the driver at the output 4th should provide. The higher a proportion is the electric machine 3 can provide the driver's desired torque, the lower the internal combustion engine portion of the driver's desired torque.

Furthermore, it is provided according to the invention that the engine control unit 9 and in the case of a hybrid vehicle, the engine control unit 9 or the hybrid control unit 11 depending on the internal combustion engine component of the torque requested by the driver, the target starting speed for the internal combustion engine 2 determined and the gearbox control unit 10 provides, either directly or with the interposition of another control unit.

The internal combustion engine is used to start up 2 from the engine control unit 9 operated with torque control. The starting clutch 8th is used to start up the gearbox control unit 10 operated with differential speed control. The torque-controlled operation of the internal combustion engine 2 via the engine control unit 9 takes place in such a way that to start up the internal combustion engine 2 provides the combustion engine component of the driver's request torque. The differential speed-controlled operation of the starting clutch 8th via the gearbox control unit 10 takes place as a function of the specified target starting speed in such a way that the starting clutch 8th a run-up of the internal combustion engine 2 controls to its target starting speed. In this way, not only can the target start-up speed be determined precisely, but a comfortable start-up process is also possible. During the start-up process, the combustion engine can 2 accelerate defined to its target starting speed.

Further details of the invention are provided with reference to the timing diagram of FIG 2 described, whereby in 2 Several curves over time are shown over time t.

This is how a curve is visualized 13 a driver desire moment. A curve 14th visualizes a from the drive unit 1 Torque provided at the transmission input, which is a sum of the torque from the internal combustion engine 2 provided torque and that of the electrical machine 3 provided torque acts. The curve progression 15th illustrates the transmission capability of the starting clutch 8th and therefore one of the starting clutch 8th transmitted actual torque.

A curve 16 illustrates a target starting speed for the internal combustion engine 2 , one Curve progression 17th a filtered target starting speed for the internal combustion engine 2 . With the curves 18th and 19th it concerns speeds at the starting clutch 8th , namely in the course of the curve 18th a speed of the starting clutch on the drive side 8th and the curve 19th by an output-side speed of the starting clutch 8th . Then when between the drive-side speed 18th and the speed on the output side 19th the starting clutch 8th If there is a difference, the starting clutch is activated 8th operated in slip.

Before time t1, the motor vehicle is at a standstill. The speed at the output 4th that depends on the speed on the output side 19th at the starting clutch 8th depends, is zero before time t1. The speed on the drive side 18th on the starting element 8th corresponds to the idling speed of the internal combustion engine 2 .

At the point in time t1, the driver actuates the accelerator pedal 12th before, with a driver request and thus driver request torque from this driver-side accelerator pedal operation 13 is determined.

As already stated, the engine control unit determines 9 or the hybrid control unit 11 depending on the driver's request 13 the combustion engine portion of the driver's request torque that the combustion engine 2 for moving off with provision of the torque requested by the driver 13 should provide.

The engine control unit 9 or the hybrid control unit 11 determined as a function of this internal combustion engine component of the driver's desired torque 13 the target starting speed 16 for the internal combustion engine 2 and provides this to the transmission control unit 10 ready.

The transmission control unit 10 determined from the engine control unit 9 or hybrid control unit 11 provided target starting speed 16 the filtered target starting speed 17th for the internal combustion engine 2 to increase the driving experience and driving comfort for the start-up process.

The determination of the target starting speed 16 from the engine control unit 9 or hybrid control unit 11 from the internal combustion engine component of the driver's desired torque takes place via an in the engine control unit 9 or hybrid control unit 11 stored torque curve of the combustion engine 2 . In such a torque curve of the internal combustion engine 2 is above the speed of the internal combustion engine 2 a torque that can be provided depending on the speed is stored. The target starting speed can easily be determined from this torque curve as a function of the internal combustion engine component of the driver's desired torque. The torque curve of the internal combustion engine 2 is preferably dependent on the ambient air pressure and / or the ambient temperature.

As already stated, the transmission control unit filters 10 preferably the target starting speed 16 , to the filtered target starting speed 17th for the internal combustion engine 2 to determine.

The internal combustion engine is used to start up 2 from the engine control unit 9 operated with torque control in such a way that the internal combustion engine 2 provides the combustion engine component of the driver's request torque. The starting element 8th is from the gearbox control unit 10 operated with differential speed control, so that the internal combustion engine starts up 2 takes place on its filtered target starting speed.

In differential speed controlled operation of the starting element 8th is the transmission capability of the same initially from time t1, at which the transmission capability of the starting element 8th Is zero, increased according to the curve shape 15th that of the starting element 8th transmittable and thus transmitted torque is smaller than that according to the curve shape 14th at the transmission input or on the drive-side half of the starting element 8th total torque provided 14th so that a torque difference between torque 14th and the torque 15th to run up the internal combustion engine 2 starting from its idling speed in the direction of the target starting speed, namely the filtered target starting speed 17th , can be done.

This is how the curve shows 18th that the above control of the starting element 8th the speed on the drive side 18th of the starting element 8th based on the idling speed of the internal combustion engine 2 increased, namely the filtered target starting speed 17th following.

According to 2 is between times t1 and t3 via a corresponding pressure control of the starting element 8th the transferability 15th the same increased linearly. The torque-regulated operation of the internal combustion engine is also used between times t1 and t2 2 the total torque of the drive unit increases linearly, namely up to time t2 the total torque of the drive unit 1 the driver's request moment 13 corresponds. As soon as the total torque of the drive unit at time t2 1 the driver's request moment 13 reached, the total torque is subsequently 14th kept constant. The transmission capability becomes between times t2 and t3 15th of the starting element 8th further increases, namely the starting element at time t3 8th according to the curve 15th transmits an actual torque, which is the total torque 14th of the drive unit 1 corresponds. To the The internal combustion engine has time t3 2 reaches its target starting speed, so that no more torque is needed to run up the internal combustion engine 2 is needed. Between times t3 and t4, the speed difference at the starting element is 8th reduced so that at time t4 the speed on the drive side 18th of the starting element 8th the speed on the output side 19th of the starting element 8th corresponds. At time t4, the slip is accordingly on the starting element 8th reduced. Then when the speed difference at the starting element 8th is less than a limit value, and then if the output-side speed continues 19th of the starting element 8th is greater than a closing speed threshold, which in turn is smaller than the target starting speed or the filtered target starting speed 17th for the internal combustion engine 2 is, the differential speed-controlled operation of the starting clutch 8th from the gearbox control unit 10 finished and then the starting element 8th then completely closed at time t4, namely brought into overpressure, so that the starting clutch 8th can transmit more torque than the drive unit 1 provides on the drive side. The starting element is accordingly after time t4 8th completely closed and brought into overpressure.

The invention further relates to a control system of a motor vehicle which is set up to carry out the above-described method on the control side. The control system comprises at least the engine control unit 9 and the transmission control unit 10 and in the case of a hybrid vehicle, the hybrid control unit as well 11 . The engine control unit 9 and in the case of a hybrid vehicle, the engine control unit 9 or the hybrid control unit 11 determines, on the one hand, the internal combustion engine component of the driver's desired torque as a function of a driver's desired torque and, on the other hand, the target starting speed for the internal combustion engine as a function of the internal combustion engine component of the driver's desired torque 2 . The target starting speed determined in this way for the internal combustion engine 2 uses the transmission control unit 10 as an input variable, so that the transmission control unit 10 the target starting speed of the internal combustion engine 2 from the engine control unit 9 and in the case of a hybrid vehicle, from the engine control unit 9 or from the hybrid control unit 11 receives. The engine control unit operates for the actual start-up 9 the internal combustion engine 2 torque controlled so that the internal combustion engine 2 provides the combustion engine component of the driver's request torque. The transmission control unit 10 operates the starting element 8th Differential speed control to allow the internal combustion engine to run up 2 to control its target starting speed. The control devices that are involved in the execution of the method according to the invention have data interfaces in order to exchange corresponding data with one another and with assemblies to be controlled and / or regulated. The control devices also include a processor for data processing and a memory for data storage. Software-side program modules that are stored in the control units are used for the software-side execution of the method according to the invention on the respective control unit.

List of reference symbols

1

Drive unit

2

Internal combustion engine

3

electric machine

4th

Downforce

5

transmission

6th

Disconnect clutch

7th

Switching element

8th

Starting element

9

Engine control unit

10

Transmission control unit

11

Hybrid control unit

12

Accelerator pedal

13

Driver request moment

14th

Total torque of the drive unit

15th

Actual torque starting element

16

Target starting speed

17th

filtered target starting speed

18th

drive-side speed starting element

19th

output-side speed starting element

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was 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.

Patent literature cited

• DE 10202520 A1 [0003]
• DE 102006053763 A1 [0004]
• DE 102006052100 A1 [0005]
• DE 102013205798 A1 [0006]

Claims (8)

Method for operating a drive train of a motor vehicle with at least one internal combustion engine (2) and, in the case of a hybrid vehicle, an additional drive unit (1) with an electric machine (3), with a transmission connected between the drive unit (1) and an output (4) (5), and with a starting element (8), with an engine control unit (9) for controlling and / regulating the operation of the internal combustion engine (2) and, in the case of a hybrid vehicle, additionally with a hybrid control unit (11) for controlling and / regulating the operation of the electric machine (3), and with a transmission control unit (10) for controlling and / or regulating the operation of the transmission (5), whereby a driver's desired torque (13) is determined and dependent on the driver's actuation of an accelerator pedal (12) for starting the vehicle Driver request torque a target starting speed (16) for the internal combustion engine (2) is determined, characterized in that the engine control unit ät (9) and, in the case of a hybrid vehicle, the engine control unit (9) or hybrid control unit (11) determines an internal combustion engine component of the driver's desired torque that the internal combustion engine (2) is to provide for starting while providing the driver's desired torque, from the engine control unit (9) and in the case of a In the hybrid vehicle, the engine control unit (9) or hybrid control unit (11) determines the target starting speed (16) for the internal combustion engine (2) as a function of this internal combustion engine component of the torque requested by the driver and is provided to the transmission control unit (10) for starting the internal combustion engine (2) from the engine control unit ( 9) is torque-controlled and the start-up element (8) is operated by the transmission control unit (10) in a differential speed control, in such a way that the internal combustion engine (2) provides the internal combustion engine component of the driver's desired torque, and the start-up element (8) accelerates the internal combustion engine (2) to the Target starting speed is controlled. Procedure according to Claim 1 , characterized in that the target starting speed (16) for the internal combustion engine (2), which is provided to the transmission control unit (10), is filtered by the transmission control unit (10) while providing a filtered target starting speed (17). Procedure according to Claim 1 or 2 , characterized in that in the differential speed control of the starting element (8) the same is initially controlled by the transmission control unit (10) in such a way that the actual torque (15) transmitted by the same and thus a transmission capacity of the starting element (8) is initially lower than that on the drive side provided torque (14) to facilitate an acceleration of the internal combustion engine (2) to the target starting speed (16, 17) that subsequently the transmission capacity of the starting element (8) is increased by the transmission control unit (10) by a speed difference between a drive-side Speed (18) and an output-side speed (19) on the starting element (8), and that the starting element (8) is then completely closed by the transmission control unit (10). Procedure according to Claim 3 , characterized in that when the speed difference on the starting element (8) is smaller than a limit value, and when the output-side speed on the starting element (8) is still greater than a closing speed threshold, which in turn is smaller than the target starting speed (16, 17) for the internal combustion engine (2), the differential speed-controlled operation of the starting element (8) is terminated by the transmission control unit (10) and the same is completely closed. Method according to one of the Claims 1 to 4th , characterized in that from the engine control unit (9) and, in the case of a hybrid vehicle, from the engine control unit (9) or hybrid control unit (11), the target starting speed (16) for the internal combustion engine (2) is dependent on the internal combustion engine component of the driver's desired torque via a torque curve of the internal combustion engine ( 2) is determined. Procedure according to Claim 5 , characterized in that the torque curve of the internal combustion engine (2) is dependent on an ambient air pressure and / or an ambient temperature. Control system of a drive train of a motor vehicle, with an engine control unit (9) for controlling and / regulating the operation of an internal combustion engine (2) and, in the case of a hybrid vehicle, additionally with a hybrid control unit (11) for controlling and / regulating the operation of an electric machine (3), and with a transmission control unit (10) for controlling and / or regulating the operation of a transmission (5), characterized in that the engine control unit (9) and, in the case of a hybrid vehicle, the engine control unit (9) or hybrid control unit (11) determines a combustion engine component of a driver's desired torque, which the internal combustion engine (2) is to provide for starting while providing the torque requested by the driver, the engine control unit (9) and, in the case of a hybrid vehicle, the engine control unit (9) or hybrid control unit (11) depending on this Combustion engine component of the driver's desired torque determines the set starting speed (16) for the combustion engine (2) and provides it to the transmission control unit (10), for starting the engine control unit (9) regulates the internal combustion engine (2) and the transmission control unit (10) regulates the starting element (8) with differential speed regulation operates in such a way that the internal combustion engine (2) provides the internal combustion engine component of the driver's desired torque and the start-up element (8) controls the internal combustion engine (2) to run up to the target starting speed. Tax system according to Claim 7 , characterized in that the same is set up, the method according to one of the Claims 1 to 6th to be carried out on the control side.

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