DE102007053706A1 - Friction clutch controlling method for motor vehicle, involves determining actual adjusting characteristic line based on already stored characteristic line for controlling friction clutch based on determined data and/or temperature model - Google Patents

Abstract

The method involves determining temperature of clutch plates, where a friction clutch includes clutch plates, central plate and/or pressure plate. A temperature gradient is determined at an inner side of the respective clutch plate. An actual adjusting characteristic line (3, 4) is determined based on already stored characteristic line for controlling the friction clutch based on the determined data and/or a temperature model. Deformation of the respective clutch plate is determined from the temperature and/or the temperature gradient.

Description

The The invention relates to a method for controlling at least one Friction clutch, in particular a double clutch with two friction clutches, a motor vehicle, wherein the friction clutch vzw. a pressure plate and a central plate and having a Temperature of at least one, vzw. determined several coupling plates becomes.

Dual clutches, in particular double clutches for dual-clutch transmissions, split the torque to be transmitted, namely to two different transmission input shafts of a dual-clutch transmission. The vzw. connectable to the first speed stage of the first input shaft, first friction clutch is generally the thermally higher loaded Friction clutch, because this friction clutch during startup heat that has escaped particularly here must dissipate. The power flow is transmitted between the motor shaft and two friction clutches. Friction clutches, especially dry clutches transmitted a torque frictionally by friction forces from the motor shaft to one - or in the case of double clutches - on two transmission input shafts.

From the DE 101 34 118 A1 is a double clutch with two dry friction clutches known. Each friction clutch has vzw. a plurality of clutch plates, in which case a clutch disc is arranged between two adjacent clutch plates. The coupling plates are vzw. rotatably connected to a motor shaft. The clutch discs are vzw. rotatably connected to a transmission input shaft. In the open state of the friction clutch, the clutch disc or the clutch discs are spaced by an air gap of the clutch plates. By means of an adjusting mechanism, the air gap can be closed and the clutch disc pressed against the adjacent clutch plates. For example. one of the clutch plates fixed and the other clutch plate can be axially movable formed as a pressure plate, so that the movable clutch plate can be pressed against the arranged between the clutch plates clutch disc, so that the clutch closes. The control of the actuating mechanism can take place by means of a characteristic curve, for example. In the form of the dependence of the transmitted torque from the travel. There are also known friction clutches, which are used, for example, in a double clutch, in which case the first friction clutch has a first pressure plate and the second friction clutch a second pressure plate, however, both friction clutches have a common central plate. The formation of a specific friction clutch is therefore dependent on the particular application.

From Disadvantage of dry friction clutches is that by the operation occurring frictional heat, in particular the clutch plates, heat the clutch disc or the central plate and these themselves can deform due to frictional heat. By the deformation may be the air gap or the gripping point of the coupling and thus change the travel. The real actuating characteristics of friction clutches change depending on from the temperature, the slip, the contact pressure and / or the speed Etc.

From the DE 102 36 540 A1 a method for driving a clutch management and / or an automatic transmission is known, wherein a gripping point of the friction clutch is determined as a function of the clutch temperature and taken into account in the control of the friction clutch. Here, the clutch temperature is then determined by a model, in particular, the gripping point of the clutch is moved accordingly. But even this known model is not yet optimally trained.

Of the The invention is therefore based on the object, a method of control a friction clutch in such a way and further develop, so that Deformation of coupling components due to temperature influences in the control of the friction clutch, in particular a double clutch with two friction clutches, considered in a cost effective manner can be.

The previously indicated object is now achieved in that at least one temperature gradient within the respective coupling plate is determined and based on the data obtained and / or a Temperature model a current actuating characteristic in dependence an already stored characteristic for controlling the friction clutch determined becomes. Of special

The advantage is that not only temperatures, but also temperature gradients, in particular the temperature differences within a coupling plate, are determined in this model. In this way, the current control characteristic can be easily determined, in particular derived from the stored characteristic curve or adapt. The comfort of coupling is thereby increased. The control or feedforward control, in particular the determination of the current actuating characteristic is vzw. divided into an axial displacement of the stored characteristic and a change in the waveform. It influences the temperature, the temperature gradient within the clutch plates or generally within the clutch components and the slip S, the contact pressure F, the rotational speed n and the transmitting torque M are detected and / or determined. In particular, the transmitting torque after be determined according to the following formula: M = μ · r · z · F

The coefficient of friction is referred to here as μ. The mean friction radius is r. The number of. Friction surfaces is designated as z. The contact force is F and the slip is S. In particular, this can be expressed by the following formula: M (T, dT, S, F, n, M) = μ (T, S, F) · r (dT) · z · F (T, dT, n, M)

• • die Erwärmung der Kupplung, da heiße Kupplungsplatten aufeinander zu wandern;
• • eine Fliehkraftverformung, wobei die Fliehkraftverformung proportional zur Motordrehzahl n und abhängig vom übertragenden Drehmoment ist; und
• • durch einen Temperaturgradienten, innerhalb der Kupplungsplatten, da die heiße Seite der Kupplungsplatten sich stärker ausdehnt als die kalte Seite, wodurch sich die Kupplungsplatte verbiegt. Dieser Effekt kann als Topfung bezeichnet werden.

Axial displacements arise, for example, by

• • the heating of the clutch, as hot clutch plates migrate towards each other;
• • a centrifugal deformation, wherein the centrifugal deformation is proportional to the engine speed n and dependent on the transmitted torque; and
• • by a temperature gradient inside the clutch plates, as the hot side of the clutch plates expands more than the cold side, causing the clutch plate to bend. This effect can be called Topfung.

The stored characteristic can be transmitted torque depending on the travel of the clutch. The current actuating characteristic is vzw. from the temperature model, in particular from the temperature-dependent deformation of the coupling plates, certainly. Vzw. is determined by the temperature and / or the temperature gradient by means of the temperature model, a deformation of the clutch plates certainly. In the temperature model in particular data of the deformation, in particular the bending, depending on the temperature gradient and / or the temperature used. As input variables the temperature model can determine the temperatures and the temperature gradients or temperature differences obtained and as output variable provide the deformations and / or Stellkennlinienverschiebungen. This depends on the particular application.

Especially the temperature and / or the temperature gradient can be constant be counted in a control device. This temperature data provide input data for tables in which the deformation the coupling plates is described. The table entries can use test bench measurements or simulations come from a calculation using a finite element method (FEM). The table then delivers as output variable vzw. the axial displacement of the characteristic curve, resulting in a better match between the real and the stored characteristic curve is achieved. The entrance described disadvantages are therefore avoided and corresponding advantages achieved.

It now gives a variety of ways, the invention To design and develop methods in an advantageous manner. For this purpose may first on the claim 1 subordinate claims are referenced. Hereinafter Now, a preferred embodiment of the invention with reference to the following drawing and the associated description explained. In the drawing shows:

1 in a schematic diagram, the torque capacity of a friction clutch in response to a travel or the axial displacement of the characteristic curve to realize the current actuating characteristic,

2 2 is a schematic diagram of the torque capacity of a friction clutch as a function of a travel or change in the shape of a characteristic curve for realizing the current actuating characteristic;

3 in a schematic flow chart, the calculation of the axial displacement of the characteristic to obtain the current actuating characteristic, and

4 in a schematic flow chart, the calculation of the current actuating characteristic from an existing characteristic.

In the 1 to 4 is - at least partially - a not shown in its entirety shown method for controlling two unillustrated friction clutches. The method can be used in particular in a double clutch with two friction clutches, which is likewise not explicitly shown.

Such dual clutches are used in particular in motor vehicles and can be part of a dual-clutch transmission. Dual-clutch transmissions divide the flow of torque by means of the double clutch on two different drive shafts, namely a first drive shaft and a second drive shaft. The double clutch has vzw. two friction clutches on. As friction clutches wet clutches or vzw. Dry clutches are used. The present "control method" relates in particular to dry clutches, ie the friction clutches are not cooled by cooling oil The friction clutches each have clutch plates to transmit torque, in particular to one or more arranged clutch discs a second friction clutch with at least one first and one second pressure plate and, respectively, in each case a so-called central plate open state of the respective friction clutch exists an air gap between the plate. The air gap determines the travel to close the clutch.

In 1 and 2 are schematically different characteristics 1 . 2 . 3 and 4 illustrated, which will be explained in more detail. In each case the torque capacity is listed 5 , ie the theoretically transmitted torque, depending on the travel 6 a friction clutch.

A disadvantage of dry friction clutches is that due to the frictional heat occurring during operation, in particular the clutch plate, the central plate and / or the clutch disc heat up and can expand and / or deform due to the frictional heat. Due to the expansion, the air gap or the gripping point of the friction clutch and thus also the travel 6 to change. The real actuating characteristics of friction clutches therefore change depending on the temperature, the slip, the contact pressure and / or the rotational speed etc.

These aforementioned disadvantages are now avoided by determining at least one temperature gradient within the respective clutch plate and, based on the determined data and / or a temperature model, determining a current actuating characteristic as a function of an already stored characteristic curve for controlling the friction clutch. By determining the temperature gradient, a bending, in particular a so-called Topfung the clutch plates are determined because the hot sides of the clutch plates expand more than the cold sides of the clutch plates. This leads, for example, to an axial displacement of the "normal" stored characteristic curve 1 towards a current characteristic 2 as indicated by the arrow P1 in the 1 is indicated. The already stored characteristic 1 is moved axially, so that then the current actuating characteristic 2 results, with the help of which now the friction clutch can be controlled or precontrolled.

The calculation of the axial displacement is in 3 shown and takes place separately for the two friction clutches of the double clutch. The starting point are the temperatures in the first pressure plate, the first friction clutch, the second pressure plate, the second friction clutch and the central plate. The first pressure plate, the second pressure plate and the central plate have vzw. each have a base body and a friction surface. The temperature 7 is measured on or in the main body of the first pressure plate. The temperature 8th is measured on the friction surface of the first pressure plate. The temperatures 9 and 10 are assigned according to the main body and the friction surface of the central plate. The temperatures 11 and 12 are assigned to the main body and the friction surface of the second pressure plate. These temperatures then become the respective temperature gradient in subsequent steps 13 . 14 . 15 and 16 calculated within each plate. There are constantly the temperatures 7 . 9 . 11 the body and the temperatures 8th . 10 and 12 the friction surfaces are read in or measured and from this the temperature difference / gradient 13 . 14 . 15 . 16 educated. The temperature differences 13 to 16 and the temperatures of the main body 7 . 9 and 11 are then evaluated.

From the temperatures 7 . 9 and 11 as well as the temperature gradient 13 . 14 . 15 and 16 becomes a deformation by means of a temperature model 17 . 18 . 19 and 20 the respective coupling plate, in particular the central plate and the first and the second pressure plate, determined. The temperature model describes the temperature- and temperature-difference-dependent deformations 17 . 18 . 19 . 20 the respective coupling plates. The temperature model can vzw. in the form of a table. The entries in this table can come from FEM simulations or from test bench measurements.

With a higher temperature, z. B. the coupling plates. If there is a temperature difference in the coupling plate, in this case between the main body and the friction surface, then a "cupping" of the coupling plate can occur 17 . 18 . 19 and 20 be vzw. described by the temperature model or can be determined by this.

Subsequently, the deformations 17 and 18 , ie the central plate and the first pressure plate, to a total deformation 21 the first friction clutch combined. The total deformation 21 does not have to be the sum of the individual values. The deformations 19 and 20 , ie the central plate and the second pressure plate, become a total deformation 22 the second friction clutch combined.

In a further step, vzw. a clutch torque 23 the first friction clutch and the associated speed 24 to a resulting centrifugal deformation 25 the first friction clutch combined. This centrifugal deformation 25 then becomes the temperature-dependent overall deformation 21 the first friction clutch added. There are also negative values of the centrifugal force deformation 25 and / or the temperature-dependent total deformation 21 possible.

Accordingly, vzw. a clutch torque 26 the second friction clutch and the associated speed 27 to a resulting centrifugal deformation 28 the second friction clutch kombi ned. This centrifugal deformation 28 then becomes the temperature-dependent overall deformation 22 added to the second friction clutch.

In one step, if necessary, for testing purposes, alternatively via a switch 29 respectively. 30 especially after activation of a manual specification 31 respectively. 32 a manual value 33 respectively. 34 be sent.

The output variables for each of the two friction clutches are each a calculated axial displacement 35 respectively. 36 sent when the manual specifications 31 and 34 are inactive. The axial displacements 35 and 36 can have the unit mm. Due to the calculated axial displacement can now, for example, as in 1 Obviously a stored characteristic 1 be moved axially, so that from this a current actuating characteristic 2 results.

The calculation of the curve of the characteristic curves 3 and 4 gem. 2 , in particular the calculation of the friction factors 37 and 38 the first and second friction clutch, is in 4 shown. The calculation is again done separately for the two friction clutches. As in 3 is in 4 the calculation for the first friction clutch in the upper half of 4 and for the second friction clutch in the lower half of 4 shown.

Input variables for the first friction factor 37 are the temperature 39 the first pressure plate, the temperature 40 the central plate, the slip 41 the first friction clutch and the current contact pressure 42 the first friction clutch. Input variables for the second friction factor 38 are the temperature 43 the second pressure plate, the temperature 44 the central plate, the slip 45 the second friction clutch and the current contact pressure 46 the second friction clutch.

From the temperature 39 the pressure plate and the temperature 40 The central plate is separated from the friction sides of the lining, a temperature-dependent coefficient of friction μ (T) is formed, wherein the coefficient of friction μ (T) with the reference numerals 47 and 48 are provided. From the coefficients of friction 47 and 48 then becomes an average 49 the temperature-dependent coefficient of friction of the first friction clutch calculated. Corresponding temperature-dependent coefficients of friction 50 and 51 as well as their mean value 52 are determined for the second friction clutch in an analogous manner.

In addition, in each case in particular a slip-dependent coefficient of friction μ (S) 53 and 54 determined for each of the two friction clutches. Furthermore, vzw. depending on the contact pressure F dependent coefficient of friction μ (F) 55 and 56 determined for each of the friction clutches. The temperature-dependent average friction coefficient μ (T) 49 respectively. 52 and the slip-dependent coefficient of friction μ (S) 53 respectively. 54 as well as the coefficient of friction μ (F) dependent on the contact force 55 respectively. 56 is _{ges ges} in a further step to a total frictional μ 57 respectively. 58 added - each again separately for each of the friction clutches. The total friction _values μ _ges 57 respectively. 58 are then by division with an unspecified Normalierwert normalized coefficients of friction μ _norm 59 respectively. 60 normalized. By this friction coefficient μ _norm 59 respectively. 60 is a qualitative change of the curve over the normal state of the curve 3 expressed to the current actuating characteristic 4 to obtain. This standardization ensures that when changing the friction linings no change in the parameters must be made because different friction linings can behave in part the same. In addition, the clutch control is simplified when friction factors are transferred from the (pre-) control. The current actuating characteristic obtained as described above 4 , as in 2 is shown by the change of the curve depending on the already known characteristic curve 3 realized. The characteristic 3 can be a stored characteristic curve, or, for example, with the in 1 represented actuating characteristic 2 , which has already been moved axially, be identical. So it is possible to combine the axial displacement and the change of the curve shape to a current actuating characteristic 2 to obtain.

For testing purposes vzw. by means of two switches 61 and 62 a manual specification 63 respectively. 64 be activated and a manual value 65 respectively. 66 be sent. Alternatively and as a rule, the normalized friction coefficients μ _norm 59 respectively. 60 as output variables or as friction factors 37 and 38 Posted. The friction factors 37 and 38 own vzw. through standardization the unit 1 , Normalized friction factors 37 and 38 greater than 1 are z. B. reached at high temperatures and give a steeper course of the control curve (see, for example. Stellkennlinie 4 in 2 ) again. Normalized total friction values less than 1 give a flatter course of the "actuating characteristic" (see, for example, characteristic curve 3 in 2 ) again. The change of the "actuating characteristic 3 "to setting characteristic 4 by rising temperatures is in 2 indicated by the arrow P2.

All parameters of the calculation are easily adaptable in the present method, so that a quick adaptation to different friction linings or clutch plate materials can be done. The calculation of the control values, in particular the normalized total friction values 37 and 38 and the axial displacements 35 and 36 , vzw. in a control device, in particular a transmission control device. In the control device are vzw. stored in a memory unit, the temperature model, for example. In tabular form. The control device comprises vzw. in addition a read-in unit and a Arithmetic unit for carrying out the control method and the other usual components.

The Control method is vzw. characterized in that dry friction clutches, in particular double clutches with two dry friction clutches be controlled. The method may be in the control device be constantly running, so that online current actuating characteristics are currently calculated. The control parameters, especially those of the temperature model, come vzw. from a model calculation or a test bench measurement. The tax procedure will run separately for each of the friction clutches. The control method separately calculates coefficients of friction which are the waveform affect the respective characteristic, and an axial displacement the respective characteristic from the temperature differences or temperature gradients realized. The tax procedure takes particular account the dependence of the actuating characteristic on the current parameters, especially the temperature, the temperature gradient, the slip, the speed, the contact pressure and the transmitted torque.

1

curve

2

Control characteristic

3

Control characteristic

4

Control characteristic

5

torque capacity

6

Travel Range

7

temperature of a basic body

8th

temperature a friction surface

9

temperature of a basic body

10

temperature a friction surface

11

temperature of a basic body

12

temperature a friction surface

13

temperature gradient

14

temperature gradient

15

temperature gradient

16

temperature gradient

17

deformation the central plate

18

deformation the first pressure plate

19

deformation the central plate

20

deformation the second pressure plate

21

total deformation the first friction clutch

22

total deformation the second friction clutch

23

clutch torque the first friction clutch

24

rotation speed the first friction clutch

25

centrifugal deformation the first friction clutch

26

clutch torque the second friction clutch

27

rotation speed the second friction clutch

28

centrifugal deformation the second friction clutch

29

switch

30

switch

31

activation manual specification

32

activation manual specification

33

manual value

34

manual value

35

axial Displacement of the first friction clutch

36

axial Displacement of the second friction clutch

37

friction factor the first friction clutch

38

friction factor the second friction clutch

39

temperature the first pressure plate

40

temperature the central plate

41

slippage

42

contact force

43

temperature the second pressure plate

44

temperature the central plate

45

slippage

46

contact force

47

Coefficient of friction μ (T)

48

Coefficient of friction μ (T)

49

middle Friction value of the first friction clutch

50

Coefficient of friction μ (T)

51

Coefficient of friction μ (T)

52

middle Friction coefficient of the second friction clutch

53

Coefficient of friction μ (S)

54

Coefficient of friction μ (S)

55

Coefficient of friction μ (F)

56

Coefficient of friction μ (F)

57

Total friction value the first friction clutch

58

Total friction value the second friction clutch

59

normalized Friction value of the first friction clutch

60

normalized Friction coefficient of the second friction clutch

61

switch

62

switch

63

activation manual specification

64

activation manual specification

65

manual value

66

manual value

P1

arrow

P2

arrow

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 10134118 A1 [0003]
• - DE 10236540 A1 [0005]

Claims (16)

Method for controlling at least one friction clutch, in particular a dual clutch with two friction clutches, a motor vehicle, wherein the friction clutch clutch plates, vzw. a pressure plate and a central plate and having a temperature ( 7 . 8th . 9 . 10 . 11 . 12 ) at least one, vzw. a plurality of coupling plates is determined, characterized in that at least one temperature gradient ( 13 . 14 . 15 . 16 ) is determined within the respective coupling plate and based on the determined data and / or a temperature model, a current actuating characteristic ( 2 . 3 . 4 ) as a function of an already stored characteristic curve ( 1 ) is determined to control the friction clutch. A method according to claim 1, characterized in that from the temperature and / or the temperature gradient by means of the temperature model, a deformation ( 17 . 18 . 19 . 20 ) of the respective coupling plate is determined. A method according to claim 1 or 2, characterized in that in the temperature model data of the type or the formation of the deformation ( 17 . 18 . 19 . 20 ) as a function of the temperature gradient ( 13 . 14 . 15 . 16 ) and / or the temperature ( 7 . 9 . 11 ) are used or available. Method according to one of the preceding claims, characterized in that the determination of the actuating characteristic ( 2 . 4 ) is divided into an axial displacement (P1) of the characteristic ( 1 ) and a change in the curve shape (P2), wherein the displacement (P1) due to the deformation ( 17 . 18 . 19 . 20 ) and the change (P2) due to friction coefficients ( 47 . 48 . 49 . 50 . 51 . 52 . 53 . 54 . 55 . 56 ) is calculated. Method according to one of the preceding claims, characterized in that the characteristic curve or current actuating characteristic ( 1 . 2 . 3 . 4 ) the torque to be transmitted ( 5 ) depending on the travel ( 6 ) represents the friction clutch and the current actuating characteristic ( 2 . 3 . 4 ) by the temperature model, in particular from the temperature-dependent deformation ( 17 . 18 . 19 . 20 ) of the clutch plates, and by friction factors ( 37 . 38 ) is determined. Method according to one of the preceding claims, characterized in that on both sides of each coupling plate, in particular on the friction surface and the side facing away from the friction surface of the coupling plate, a temperature ( 7 . 8th u. 9 . 10 u. 11 . 12 ) and from each of these two temperatures ( 7 . 8th u. 9 . 10 u. 11 . 12 ) the temperature gradient ( 13 . 14 . 15 . 16 ) is determined. Method according to one of the preceding claims, characterized in that the friction factor ( 35 . 36 ) from a temperature-dependent coefficient of friction ( 47 . 48 . 50 . 51 ), a slip-dependent coefficient of friction ( 53 . 54 ) and / or a friction value dependent on the contact force ( 55 . 56 ) is calculated. Method according to one of the preceding claims, characterized in that in determining a total deformation ( 21 ) additionally a centrifugal deformation ( 25 . 28 ) as a function of the rotational speed ( 24 . 27 ) and the transmitting torque ( 23 . 26 ) is taken into account. Method according to one of the preceding claims, characterized in that the actuating characteristic ( 2 . 3 . 4 ) as a function of the temperature ( 7 to 12 ) of the respective coupling plate, the temperature gradient ( 13 . 14 . 15 . 16 ) of the respective clutch plate, the slip ( 41 . 45 ), the contact pressure ( 42 . 46 ) and the speed ( 24 . 27 ) is detected. Method according to one of the preceding claims, characterized in that the temperature ( 7 to 12 . 41 . 42 . 43 . 44 ) and / or the temperature gradient ( 13 . 14 . 15 . 16 ) is updated, in particular measured. Method according to one of the preceding claims, characterized in that the friction clutch as a dry clutch is trained. Method according to one of the preceding claims, characterized in that a double clutch with a first and a second dry-running friction clutch is driven. Method according to one of the preceding claims, characterized in that each friction clutch as clutch plates a pressure plate and a central plate, wherein the central plate is common to both friction clutches. Method according to one of the preceding claims, characterized in that for both friction clutches each have a characteristic curve ( 1 ) or a current actuating characteristic ( 2 . 3 . 4 ) is calculated. Method according to one of the preceding claims, characterized in that for the actuating characteristic ( 2 . 3 . 4 ) a friction factor ( 35 . 36 ) as a function of the temperature ( 39 . 40 . 43 . 44 ) of the respective clutch plate, the slip ( 41 . 45 ) in the friction clutch and the current contact force ( 42 . 46 ) is determined. Method according to one of the preceding claims, characterized in that a read-in unit, an output unit, a memory unit and a computing unit for carrying out the method is provided for.