DE102018222089A1 - Method and control device for operating a drive train of a motor vehicle - Google Patents

Abstract

Method for operating a drive train of a motor vehicle, with a drive assembly (1) and a transmission (3) connected between the drive assembly (1) and an output (2) with a plurality of shifting elements (4), when, in the case of a transmission (3 ) engaged, non-positive gear is driven with a gear-dependent target gear ratio, it is monitored whether an actual gear ratio deviates from the target gear ratio by more than a limit value despite the gear being engaged, and when it is determined that the actual gear ratio deviates from the target gear ratio by more than the limit value, a flare state of the transmission (3) is detected, and the following steps are carried out when or after the flare state is detected: determining that shift element (4) of the transmission (3 ), which has a low transfer capability. Determining an under-transfer capability torque for the switching element (4) which has the under-transfer capability. Determining a compensation torque for the switching element (4) which has the low transmission capability. Actuation of the switching element (4) which has the reduced transmission capacity, depending on the determined transmission loss torque and in dependence on the determined compensation torque, in order to sew the actual gear ratio to the target gear ratio and thus to leave the flare state of the transmission (3).

Description

The invention relates to a method for operating a drive train of a motor vehicle. Furthermore, the invention relates to a control device for performing the method.

Drive trains of motor vehicles with a transmission connected between a drive unit and an output are well known from practice. Furthermore, it is known that a transmission comprises a plurality of shifting elements, which can be designed as friction-locking shifting elements or also as form-locking shifting elements. When a non-positive gear is engaged in a transmission, a first number of shift elements of the transmission is closed and a second number of shift elements of the transmission is open. If a non-positive gear is engaged in the gearbox, the gearbox is driven with a defined gear ratio. Depending on this gear-dependent gear ratio, speeds and torques are converted and the traction power available from the drive unit is made available by the gearbox on the output. The transmission capability of a switching element may be reduced due to a defect in a switching element. In this case, the transmission may no longer be able to completely transmit a torque offered by the drive unit in the direction of the output, in which case this torque, which can no longer be transmitted, leads to an increase in the speed at the transmission input. In this case, an actual gear ratio is formed when the non-positive gear is engaged, which deviates from the gear-dependent target gear ratio. Such a state of the transmission is referred to as a flare state. It is already known from practice to monitor the transmission capability of shift elements of a transmission with the aid of a so-called gear monitoring. If it is determined on a gearbox that one of the shifting elements must have a reduced transmission capacity, gear shifts are carried out in practice in order to identify the shifting element whose transmission capacity is restricted in the exclusion process. Such unnecessary circuits can cause consequential damage to switching elements and should be avoided.

From the DE 10 2016 212 359 B4 A method for determining transmission internal torques on shifting elements of a transmission is known, by means of which a shifting element of a transmission can be computationally determined, the transmission capacity of which is reduced, ie which has a low transmission capacity.

Although it is already known in principle to computationally determine a shift element of a transmission which has a low transmission capability, it has hitherto been difficult to leave the flare state of the transmission in a defined manner.

There is therefore a need for a method for operating a drive train and for a control device for carrying out the method, with the aid of which, when a flare state of the transmission is detected and that switching element of the transmission which has a low transmission capability is determined, it is properly left of the flare state of the transmission.

Proceeding from this, the object of the invention is to create a novel method and a control device for a drive train of a motor vehicle.

This object is achieved by a method for operating a drive train of a motor vehicle according to claim 1.

According to the invention, when driving in a gear-locked, non-positive gear with a gear-dependent, defined target gear ratio, it is monitored whether an actual gear ratio deviates from the target gear ratio by more than a limit value despite the gear being engaged.

• Ermitteln desjenigen Schaltelements des Getriebes, welches eine Minderübertragungsfähigkeit aufweist.
• Ermitteln eines Minderübertragungsfähigkeitsmoments für dasjenige Schaltelement des Getriebes, welches die Minderübertragungsfähigkeit aufweist.
• Ermitteln eines Kompensationsmoments für dasjenige Schaltelement des Getriebes, welches die Minderübertragungsfähigkeit aufweist.

If it is determined that the actual gear ratio deviates from the target gear ratio by more than the limit value, a detection is made of a flare state of the transmission, the following steps being carried out when or after the flare state of the transmission is recognized:

• Determine the shift element of the transmission that has a reduced transmission capability.
• Determination of a torque transmission capability for that shift element of the transmission that has the transmission capability.
• Determining a compensation torque for that shift element of the transmission which has the reduced transmission capacity.

Activation of the shift element of the transmission which has the reduced transmission capacity, depending on the determined transmission loss torque and in dependence on the determined compensation torque, in order to sew the actual gear ratio to the target gear ratio and thus to leave the flare state of the transmission.

The present invention proposes, on the one hand, for the switching element that has a reduced transmission capability when the transmission is in a flare state to determine a torque transmission capability and, on the other hand, a compensation torque and then, depending on these two moments, to actuate the shifting element which has the transmission capability to approximate the actual gear ratio of the gearbox to the target gear ratio of the engaged, non-positive gear and thus the flare state of the gearbox defined to leave.

According to an advantageous further development, a first dynamic torque is determined for the shift element of the transmission which has the reduced transmission capacity, depending on a temporal actual gradient and target gradient of the transmission input speed and a mass inertia related to the drive unit, from which the reduced transmission capacity torque is determined. The torque transmission capability torque is preferably determined from this first dynamic torque as a function of a gear-dependent and / or shift element-dependent support factor. The torque transfer capability torque can hereby be determined particularly advantageously.

According to an advantageous further development, a second dynamic torque is determined for that shift element of the transmission that has the reduced transmission capability, depending on a time-based compensation gradient of the transmission input speed and a mass inertia related to the drive unit, from which the compensation torque is determined. The compensation torque is preferably determined from this second dynamic torque as a function of a gear-dependent and / or shift element-dependent support factor. The compensation torque can hereby be determined particularly advantageously.

According to an advantageous further development, the desired-time compensation gradient of the transmission input speed is preferably dependent on a temperature of the shifting element which has the low transmission capability and / or on a torque of the shifting element which has the low transmission capability and / or depending on a differential speed of the shifting element which which has reduced transmission capability, and / or determined depending on a transmission input torque. This is preferred in order to determine the desired time compensation gradient of the transmission input speed.

The control device according to the invention is defined in claim 10.

• 1 ein Blockschaltbild eines Antriebsstrangs eines Kraftfahrzeugs;
• 2 ein Signalflussdiagramm zur Verdeutlichung des erfindungsgemäßen Verfahrens;
• 3 ein Zeitdiagramm zur weiteren Verdeutlichung des erfindungsgemäßen Verfahrens.

Preferred further developments result from the subclaims and the following description. Exemplary embodiments of the invention are explained in more detail with reference to the drawing, without being restricted to this. It shows:

• 1 a block diagram of a drive train of a motor vehicle;
• 2nd a signal flow diagram to illustrate the inventive method;
• 3rd a timing diagram to further illustrate the method according to the invention.

The invention relates to a method and a control device for operating a drive train of a motor vehicle.

1 shows a highly schematic block diagram of a drive train of a motor vehicle, the drive train being a drive unit 1 and one between the drive unit 1 and an output 2nd shifted transmission 3rd includes. With the transmission 3rd is an automated or automatic manual transmission that converts speeds and torques and thus the traction power offered by the drive unit 1 on the output 2nd provides.

The gear 3rd includes several switching elements 4th , where in 1 just a switching element 4th is shown. With the switching elements 4th of the transmission 3rd it is a matter of frictional shifting elements and, if necessary, positive shifting elements, in each inserted, non-positive gear of the transmission 3rd a first number of switching elements 4th closed and a second number of switching elements 4th is open. To carry out a gear change in the transmission 3rd a previously closed switching element is opened and a previously opened switching element is closed. According to 1 is between the drive unit 1 and the gear 3rd a disconnect clutch 5 switched.

Operation of the drive unit 1 is from an engine control unit 6 controlled and / or regulated. Operation of the transmission 3rd is from a transmission control unit 7 controlled and / or regulated. To do this, replace the engine control unit according to the double arrows shown 6 with the drive unit 1 and the transmission control unit 7 with the gear 3rd Data from. Also replace engine control unit 6 and transmission control unit 7 data from one another.

Then when the in 1 shown drive train in the transmission 3rd A non-positive gear is firmly engaged and the vehicle is driven with a defined target gear ratio that is dependent on the non-positive gear, it is monitored whether an actual gear ratio deviates from a target gear ratio by more than a limit value, despite the fact that a non-positive gear is engaged. If this is the case, it is concluded that for the transmission 3rd there is a so-called flare state.

• Ermitteln desjenigen Schaltelements 4 des Getriebes 3, welches eine Minderübertragungsfähigkeit aufweist.
• Ermitteln eines Minderübertragungsfähigkeitsmoments für dasjenige Schaltelement 4 des Getriebes 3, welches die Minderübertragungsfähigkeit aufweist.
• Ermitteln eines Kompensationsmoments für dasjenige Schaltelement 4 des Getriebes 3, welches die Minderübertragungsfähigkeit aufweist.

When or after detection of such a flare condition in the transmission 3rd the following steps are carried out:

• Determine that switching element 4th of the transmission 3rd , which has a low transfer capability.
• Determination of a transfer capability torque for that switching element 4th of the transmission 3rd , which has the shortage transfer capability.
• Determining a compensation torque for that switching element 4th of the transmission 3rd , which has the shortage transfer capability.

Driving that switching element 4th of the transmission 3rd , which has a reduced transmission capacity, depending on the determined transmission loss torque and in dependence on the determined compensation torque, in order to approximate the actual gear ratio of the gearbox to the target gear ratio of the engaged, non-positive gear and the flare state of the gearbox 3rd to leave.

Further details of the invention are described below with reference to the signal flow diagram of FIG 2nd described.

In one block 8th , 12 there is a check whether the gearbox 3rd a flare condition occurs when driving in a fixed, non-positive gear. To do this, the block 8th several input variables 9 , 10th and 11 provided, namely with the input variable 9 the target ratio of the fixed, non-positive gear of the transmission 3rd , with the input variable 10th the actual speed of the gearbox output and with the input variable 11 the actual speed of the gearbox input. In the block 8th an actual gear ratio is then calculated depending on the actual speed of the gearbox output and the actual speed of the gearbox input 12 is compared with the target translation. In one block 12 it is checked whether the actual translation deviates from the target translation by more than a limit.

If this is not the case, it starts from block 12 on block 8th branched back. However, is in block 12 If the fact that the actual gear ratio deviates from the target gear ratio by more than the limit value is determined, then a detection of a flare state of the transmission is made and starting from block 12 on block 13 branches.

In the block 13 becomes the switching element of the transmission 3rd determined that is closed when driving in the engaged, non-positive gear and has a low transmission capacity.

This switching element, which has the low transmission capability, is preferably determined on the basis of the DE 10 2016 212 359 B4 known way. Details of how a switching element that has a low transmission capability can be determined mathematically on the basis of a system of equations are accordingly known to those skilled in the art from DE 10 2016 212 359 B4 known, so at this point on the DE 10 2016 212 359 B4 is referred.

The block is the output variable 13 that switching element of an inserted, non-positive gear, which is closed in the inserted, non-positive gear and has a reduced transmission capacity.

In a subsequent block 14 is for that switching element of the transmission 3rd which is in block 13 was determined as a switching element with reduced transfer capability, a reduced transfer capability torque was determined.

This is the block 14 on the one hand as an input variable 15 an actual gradient of the transmission input speed and as a further input variable 16 one on the drive unit 1 related inertia provided, depending on those for that switching element 4th , which has the shortage transfer capability, a first dynamic moment is determined. In the case of inertia, the block 14 as input variable 16 is provided, it is the inertia of the drive train that the same between the drive unit 1 and the switching element 4th with the transferability.

The first dynamic moment, which is in block 14 is determined, is also dependent on a temporal target gradient of the transmission input speed. This time target gradient of the transmission input speed is determined as a function of the target transmission input speed, the product of the target gear ratio and the actual output speed at the output 2nd corresponds.

The first dynamic moment corresponds to the product of the inertia and the difference between the difference between the actual gradient and the target gradient of the transmission input speed. The first dynamic moment is with a support factor of the transmission 3rd calculated to calculate the transfer capability torque from this first dynamic torque, the support factor of the transmission 3rd is dependent on the engaged non-positive gear and on the switching element that has the low transmission capacity.

The block 14 outputs the reduced transfer torque as an output variable.

In a subsequent block 17th takes place analogously to the block 12 again a check to see if the flare condition of the transmission 3rd is present.

Below is in a block 18th the compensation torque for that switching element 4th of the transmission 3rd determined which has the transfer capability. This compensation moment 18th is determined depending on the input variables, namely the input variables 19th and 16 . With the input size 16 it is again the mass inertia of the drive train starting from the drive unit 1 towards the switching element 4th with the transferability. With the input size 19th it is a temporal target compensation gradient of the transmission input speed.

From the product of these input quantities 16 and 19th a second dynamic torque is determined, which is initially related to the drive and by offsetting with the support factor of the transmission 3rd is converted into the compensation torque, the support factor of the transmission 3rd in turn is gear-dependent. The block 18th therefore outputs the compensation torque as the output variable.

In one block 20th the switching element is then activated 4th of the transmission 3rd , which has the shortage transfer capability, depending on the in block 14 ascertained reduced transfer capacity moment as well as depending on the in block 18th Compensation torque determined in order to bring the actual gear ratio closer to the target gear ratio as a result of this control, and thus the flare condition on the transmission 3rd to leave.

As a result, takes place in block 17th continuous monitoring for a flare condition on the gearbox 3rd is present, if then still on the transmission 3rd there is a flare state in block 18th the compensation torque is continuously recalculated to control the switching element 4th adapt. For controlling the switching element 4th with less transferability, this remains in block 14 Undetected transmission capacity torque unchanged, that in block 18th The compensation torque determined is continuously adjusted.

The adjustment of the compensation torque in block 18th is from the target compensation gradient 19th depending on the gearbox input speed, the in block 21st of the 2nd is determined. The determination of the target compensation gradient 19th the transmission input speed in block 21st takes place depending on the input variables 22 and or 23 and or 24th and or 25th , which is the input variable 22 by a current actual differential speed on the switching element 4th , which has the transfer capability, is the input variable 23 around a current temperature of the switching element 4th acts, which has the transfer capability, where it is the input variable 24th a current transmitted torque on the switching element 4th which has the transfer capability, and which is the input variable 25th is a current moment of the transmission input. The target compensation gradient is preferably used 19th the transmission input speed depending on these four input variables 22 , 23 , 24th and 25th determined. However, it is also possible to use only a few of these input variables for determining the target compensation gradient 19th the gearbox input speed or taking additional input variables into account.

In one block 26 of the signal flow diagram of the 2nd the block is saved 14 determined transmission capacity torque, in this regard, an adaptation value for the control of that switching element of the transmission 3rd to determine which one has the lower transferability.

When using the method described above, the in 3rd form the temporal signal curves shown. So are in 3rd Three temporal signal curves are shown over time t, namely with one signal curve 27th a course of a target transmission input speed of the transmission 3rd which is a product of the target translation of the in the gearbox 3rd engaged gear and a measured actual output speed at the output 2nd corresponds. A curve 28 visualizes an actual curve of the transmission input speed. The waveforms 27th and 28 can be seen that the actual course of the transmission input speed deviates from the gear-dependent target course, so that in 3rd at time t1 to a flare state in the transmission 3rd is closed.

The waveform 29 visualizes a torque curve in the transmission 3rd , on that switching element 4th of the transmission 3rd , which has a reduced transmission capacity when the gear is firmly engaged. So visualized 3rd with the reference number 30th a reduced transmission capacity torque, which indicates the flare state in the transmission 3rd caused. With detection of the flare status in the transmission 3rd at time t1 for that switching element 4th of the transmission 3rd , which has the reduced transfer capability, as described above, determines the reduced transfer capability torque and the compensation torque in order to control the switching element, which the Has reduced transferability to change. So is the transfer capability torque with the reference number 31 and the compensation torque with the reference number 32 visualized. With increasing flare reduction and increasing reduction in a differential speed on the switching element 4th the compensation moment becomes known when the transfer capability is recognized 32 in the sense of the blocks 17th , 18th and 20th continuously reduced.

The invention further relates to a control device for operating the drive train of the motor vehicle, the control device executing the method described above on the control side. The control device according to the invention is in particular the transmission control device 7 .

The transmission control unit 7 has hardware-side means and software-side means for executing the method on the control side, the hardware-side means being data interfaces, a processor and a memory. The data interfaces are used to exchange data with the modules involved in the implementation of the method according to the invention. The processor is used for data processing and the memory for data storage. The software-side means include program modules for carrying out the method according to the invention.

The control unit 7 then monitors when in the transmission 3rd a non-positive gear is engaged and the non-positive gear is driven in how the target gear ratio relates to the actual gear ratio of the transmission, when the control unit 7 determines that the actual gear ratio deviates from the target gear ratio by more than a limit value to a flare state of the transmission 3rd recognizes. Then when the control unit 7 the flare condition of the transmission 3rd recognizes, the same carries out the following steps: determining that switching element 4th of the transmission 3rd , which has the shortage transfer capability. Determining the transfer capability torque for that switching element 4th of the transmission 3rd , which has the shortage transfer capability. Determining the compensation torque for that switching element 4th of the transmission 3rd , which has the shortage transfer capability. Control of that switching element 4th of the transmission 3rd , which has the reduced transmission capacity, namely as a function of the determined transmission loss torque and the determined compensation torque, in order to approximate the actual gear ratio to the target gear ratio and thus the flare state of the transmission 3rd to leave.

Reference symbol list

1

Drive unit

2nd

transmission

3rd

Downforce

4th

Switching element

5

Separating clutch

6

Engine control unit

7

Transmission control unit

8th

Block target translation determination

9

Input variable target translation

10th

Input variable actual speed gearbox output

11

Input variable actual speed transmission input

12

Block query flare state

13

Block switching element determination

14

Block of transferability torque determination

15

Input variable actual gradient gearbox input speed

16

Mass inertia

17th

Block query flare state

18th

Compensation torque determination block

19th

Input variable target compensation gradient transmission input speed

20th

Block switching element control

21st

Block target compensation gradient determination

22

Input variable actual differential speed switching element

23

Input variable temperature switching element

24th

Input variable moment switching element

25th

Input variable torque transmission input

26

Block adaptation value

27th

Target curve shape of transmission input speed

28

Actual curve shape of transmission input speed

29

Curve torque

30th

Reduced transfer torque

31

Reduced transfer torque

32

Compensation moment

QUOTES INCLUDE IN THE DESCRIPTION

This list of documents listed by the applicant has been generated automatically and is only included 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 102016212359 B4 [0003, 0028]

Claims (11)

Method for operating a drive train of a motor vehicle, with a drive unit (1) and a transmission (3) connected between the drive unit (1) and an output (2) with a plurality of shifting elements (4), If, in a non-positive gear engaged in the gearbox (3), a gear-dependent, defined target gear ratio is used, it is monitored whether an actual gear ratio deviates from the target gear ratio by more than a limit value despite the gear being engaged, If it is determined that the actual gear ratio deviates from the target gear ratio by more than the limit value, a detection of a flare state of the transmission (3) is detected, the following steps being carried out when or after recognizing the flare state of the transmission (3): Determining that shift element (4) of the transmission (3) which has a reduced transmission capacity, Determining a torque transmission capability for that shift element (4) of the transmission (3) which has the transmission capability, Determining a compensation torque for that shift element (4) of the transmission (3) which has the reduced transmission capability, Actuation of the shift element (4) of the transmission (3) which has the reduced transmission capacity, depending on the determined transmission loss torque and in dependence on the determined compensation torque, in order to sew the actual gear ratio to the target gear ratio and thus the flare state of the transmission (3) to leave. Procedure according to Claim 1 , characterized in that for the shift element (4) of the transmission (3) which has the reduced transmission capability, depending on a time-actual gradient of a transmission input speed, a time-desired gradient of the transmission input speed and a mass inertia related to the drive unit (1) dynamic moment is determined, from which the transfer capability torque is determined. Procedure according to Claim 2 , characterized in that the reduced transmission capacity torque is determined from this dynamic moment depending on a gear-dependent and / or shift element-dependent support factor. Procedure according to Claim 2 or 3rd , characterized in that the target gradient of the transmission input speed is determined from the target transmission input speed, which corresponds to the product of the target gear ratio and the output speed. Procedure according to one of the Claims 1 to 4th , characterized in that for the shift element (4) of the transmission (3) which has the reduced transmission capacity, a dynamic torque is determined from which the .depending on a temporal target compensation gradient of the transmission input speed and a mass inertia related to the drive unit (1) Compensation moment is determined. Procedure according to Claim 5 , characterized in that the compensation torque is determined from this dynamic torque depending on a gear-dependent and / or shift element-dependent support factor. Procedure according to Claim 5 or 6 , characterized in that the temporal target compensation gradient of the transmission input speed depends on a temperature of the switching element (4), which has the low transmission capability, and / or depending on a moment of the switching element (4), which has the low transmission capability, and / or depending on a differential speed of the shift element (4), which has the reduced transmission capability, and / or is determined as a function of a transmission input torque. Procedure according to one of the Claims 1 to 7 , characterized in that for the actuation of that switching element (4) of the transmission (3) which has the reduced transmission capability, the determined transmission loss torque is kept unchanged and the compensation torque is continuously determined anew. Procedure according to one of the Claims 1 to 8th , characterized in that the determined low transmission capacity torque is used as an adaptation value for the control of that switching element (4) of the transmission (3) which has the low transmission capacity. Control device (7) for operating a drive train of a motor vehicle, with a drive unit (1) and a transmission (3) connected between the drive unit (1) and an output (2) with a plurality of switching elements (4), the control unit (7) then If, in a non-positive gear engaged in the gearbox (3), a gear-dependent, defined target gear ratio is used, the system monitors whether an actual gear ratio deviates from the target gear ratio by more than a limit value despite the gear being engaged, whereby the control unit (7) when it determines that the actual gear ratio deviates from the target gear ratio by more than the limit value, recognizes a flare state of the transmission (3), The control unit (7) executes the following steps when or after recognizing the flare state of the transmission (3): determining that shift element (4) of the transmission (3) which has a reduced transmission capacity, determining a reduced transmission capacity torque for that shift element (4) of the Gearbox (3) which has the low transfer capability, determining a compensation torque for that shift element (4) of the gearbox (3) which has the low transfer capability, actuating that shift element of the gearbox (3) which has the low transfer capability depending on the determined transfer capability torque and of the compensation torque determined in order to sew the actual gear ratio to the target gear ratio and thus to leave the flare state of the transmission (3). Control unit after Claim 10 , characterized in that the same the method according to one of the Claims 1 to 9 executed on the control side.

Images