DE102011011921B4 - Method for monitoring a clutch and transmission - Google Patents

Abstract

Method for monitoring a clutch, in particular a powershift clutch (15) of a drive train (3) of a motor vehicle (5), the clutch (15) being preceded by an engine output shaft (13) and a transmission input shaft (23) of a transmission (1) of the drive train (3) ) is connected downstream, with the following steps: - keeping the clutch (15) open, - determining a rotational acceleration variable ((ω'accelerate, ω'deceleration), - disengaging or disengaging a gear of the transmission (1), - double determination of the angular acceleration variable ((ω'accelerate, ω'deceleration) for a positive and for a negative speed difference between the engine output shaft (13) and the transmission input shaft (23), - determination of a clutch drag torque (47,49 ) as a function of the twice determined angular acceleration variable ((ω'accelerate, ω'deceleration) using the formula: M coupling = Jinput shaft * (| ω'deceleration n | + | ω'accelerate |) / 2, where M clutch is the clutch drag torque, J input shaft is a mass moment of inertia of the transmission input shaft (23), ω 'decelerates a determined or determinable rotational acceleration of the transmission input shaft (23) with a negative speed difference between the engine output shaft (13) and the 23) and ω 'accelerate an ascertained or ascertainable angular acceleration of the transmission input shaft (23) at a positive speed difference between the engine output shaft (13) and the transmission input shaft (23), characterized by: - determining a temperature of the transmission (1), - determining the clutch drag torque ( 47.49) additionally depending on the temperature.

Description

The invention relates to a method for monitoring a clutch, in particular a powershift clutch, of a drive train of a motor vehicle, the clutch being preceded by an engine output shaft and a transmission input shaft of a transmission of the drive train as well as a transmission according to the method.

The DE 10 2010 024 941 A1 discloses a method of controlling a dual clutch transmission. The DE 199 31 160 A1 discloses a method for clutch characteristic curve adaptation. The DE 10 2006 019 824 A1 discloses a method for determining a torque characteristic of an automated friction clutch.

Methods for monitoring a clutch, in particular a power shift clutch, of a drive train of a motor vehicle are known. For example, an engagement point of the powershift clutch can be determined with the aid of a speed gradient of the transmission input shaft. It is known to engage the powershift clutch and thereby observe a speed behavior of the transmission input shaft in order to deduce from this the touch point of the powershift clutch. The DE 10 2007 025 253 A1 relates to a method for determining the point of engagement of a clutch of an automated dual clutch transmission of a vehicle while the drive unit is running. The DE 199 39 818 C1 relates to a method for controlling a drive train of a vehicle, in which a powershift clutch is engaged for torque transmission while driving and the point of engagement of a parallel disengaged powershift clutch is determined by an unsteady engagement process. The EP 1 741 950 A1 relates to a method for determining a gripping point of a clutch. The process starts with a fully closed clutch and determines two clutch positions that are closely related in time and both are included in the calculation of the gripping point. While the clutch position is determined when the clutch is closing, the clutch is opened when the clutch position is determined. Methods for adapting the characteristic curve of the clutch are also known. The DE 103 08 517 A1 relates to a method for adapting the clutch characteristics of an automated double clutch transmission, in particular of a motor vehicle, with the engine running. The EP 1 067 008 B1 relates to a method for adapting the clutch characteristics of an automated double clutch transmission, in particular of a motor vehicle, wherein in particular a speed gradient of a free transmission input shaft is determined.

The object of the invention is to enable improved monitoring of a clutch, in particular a power shift clutch, of a drive train of a motor vehicle, in particular to identify a state of the clutch.

The object is achieved in a method for monitoring a clutch, in particular a power shift clutch, of a drive train of a motor vehicle, the clutch being preceded by an engine output shaft and a transmission input shaft of a transmission of the drive train being connected by the characterizing features of claim 1. These include keeping the power shift clutch open, determining a rotational acceleration variable that characterizes the rotational acceleration behavior of the transmission input shaft of the transmission, disengaging or maintaining a gear of the transmission, thereby double determination of the rotational acceleration variable for a positive and a negative speed difference between the motor output shaft and the transmission input shaft and determination a clutch drag torque is provided as a function of the twice determined rotational acceleration variable. If necessary, the disengagement and / or the disengagement holding can take place several times, with the angular acceleration variable being determined for the respective speed difference. If necessary, the speed difference can also be changed during the determination for double determination. The clutch drag torque for characterizing a state of the clutch can advantageously be determined. In principle, knowledge of the clutch drag torque is advantageous because, particularly in the case of double clutch transmissions, a clutch drag torque is always associated with a power loss and thus also with a thermal load on the clutch. The clutch drag torque can advantageously be used for further regulation and / or control processes as an influencing variable, for example a disturbance variable. This can be done, for example, to determine the force required when synchronizing gears of the transmission, for example in the form of a load spectrum for a transmission actuator and / or a synchronization device of the transmission. If the clutch drag torque assumes undesirably large values, countermeasures can advantageously be taken, for example to prevent excessive energy input into the clutch and the associated wear of the power shift clutch. In principle, this can advantageously improve the efficiency of the clutch and / or the downstream transmission as well as the comfort behavior of the clutch and the transmission.

In a preferred exemplary embodiment of the method, the rotational acceleration variable is determined by means of a sensor device assigned to the transmission input shaft. The rotational acceleration variable can advantageously be determined by means of the sensor device. For this purpose, the sensor device can, for example, have a rotation rate sensor and, downstream of this, a differentiating element for determining a speed gradient. The angular acceleration variable can have a speed gradient of the transmission input shaft. The clutch can be a dry or wet running friction clutch, for example a multi-disc clutch.

In a further preferred exemplary embodiment of the method, the rotational acceleration variable is determined as an angular acceleration. With knowledge of the angular acceleration, the clutch drag torque can advantageously be determined for the positive speed difference and for the negative speed difference. A positive speed difference can be understood, for example, to mean that the engine output shaft rotates faster than the transmission input shaft. Correspondingly, a negative speed difference can be understood to mean that the engine output shaft rotates more slowly than the transmission input shaft.

wobei

• M_Kupplung das Kupplungsschleppmoment,
• J_{Eingangswelle} ein Massenträgheitsmoment der Getriebeeingangswelle,
• ω'_Verzögern die Winkelbeschleunigung bei der negativen Drehzahldifferenz und
• ω'_{Beschleunigen} die Winkelbeschleunigung bei der positiven Drehzahldifferenz sind,

vorgesehen. Vorteilhaft können die Beträge der Winkelbeschleunigungen für die positive Drehzahldifferenz und die negative Drehzahldifferenz gemittelt werden, also addiert und anschließend halbiert, wobei vorteilhaft übrige Störmomente herausfallen und als Ergebnis das Kupplungsschleppmoment zur Verfügung steht.According to the invention, the clutch drag torque is determined using the formula: $${\text{M.}}_{\text{coupling}}{\text{= J}}_{\text{Input shaft}}*\left(\left|\mathrm{\omega }{\text{'}}_{\text{Delay}\ddot{\text{O}}\text{gladly}}\right|+\left|\mathrm{\omega }{\text{'}}_{\text{Accelerate}}\right|\right)/\mathrm{2,}$$

in which

• M _{clutch is} the clutch drag torque,
• J _{input shaft} a mass moment of inertia of the transmission _input shaft,
• ω ' _Decelerate the angular acceleration with the negative speed difference and
• ω ' _{Accelerate are} the angular acceleration at the positive speed difference,

intended. Advantageously, the amounts of the angular accelerations for the positive speed difference and the negative speed difference can be averaged, that is, added and then halved, the remaining disturbing torques advantageously being eliminated and the clutch drag torque being available as a result.

According to the invention, determining a temperature of the transmission and determining the clutch drag torque are additionally provided as a function of the temperature. Temperature influences on the transmission can advantageously be compensated. It is possible, for example, to also use a temperature model of the transmission. Alternatively and / or in addition, it is possible to use the method only within certain, predetermined temperature bands, for example if an operating temperature has been reached.

In a further preferred exemplary embodiment of the method, the clutch drag torque is determined during a neutral phase of the transmission. During the neutral phase of the transmission, the transmission input shaft can advantageously run freely when the clutch is held open, so that the speed gradient advantageously enables an indication or calculation of the clutch drag torque.

In a further preferred exemplary embodiment of the method, multiple implementation of the method for different gear changes of the transmission in different directions is provided. For example, a gear change from a first gear into a neutral position into a third gear and backwards from a third gear into a neutral position into a first gear can be provided. In this way, further influences, for example originating from the synchronization device of the transmission, can advantageously be averaged out.

In a further preferred exemplary embodiment of the method, a threshold value for the clutch drag torque is specified and the powershift clutch is displayed if the clutch drag torque determined exceeds the threshold value. The monitoring of the clutch drag torque can advantageously be included in what is known as an on-board diagnosis, with faulty components of the vehicle, in particular the drive train, being indicated to a driver of the motor vehicle, for example by lighting up a warning lamp, by recommending a visit to a workshop and / or similar. Alternatively and / or in addition, it is also possible to display the transmission simply by making an entry in a fault memory of the motor vehicle.

In a further preferred exemplary embodiment of the method, it is provided that the transmission is a sub-transmission of a double clutch transmission. The method can advantageously also be used in dual clutch transmissions, it being possible for this to be carried out separately for each partial transmission, which is preceded by its own clutch. This can take place, for example, during gear changes, freewheeling phases and / or during a load-free phase of the respective sub-transmission.

The object is also achieved with a transmission, in particular a dual clutch transmission, set up to carry out a method described above. The advantages described above result.

Further advantages, features and details emerge from the following description, in which an exemplary embodiment is described in detail with reference to the drawing. Identical, similar and / or functionally identical parts are provided with the same reference symbols.

The only attached figure shows a torque flow diagram of a double clutch transmission of a drive train of a motor vehicle.

1 shows a torque flow diagram of a transmission 1 , the part of a drive train only partially shown 3 of a motor vehicle also only partially shown 5 is. The gear 1 is designed as a dual clutch transmission and has a first partial transmission 7th and a second partial transmission 9 on. The drive train has one by means of the reference number 11 only indicated drive source. The drive source 11 drives an engine output shaft 13th on who has a powershift clutch 15th is downstream. The powershift clutch 15th has a first partial clutch 17th and a second partial clutch that can be controlled separately from it 19th on. With the partial couplings 17th , 19th it can in particular be dry or liquid clutches, in particular multi-disk clutches. in particular, the powershift clutch 15th be designed to be partially automated or automated.

The first partial coupling 17th the powershift clutch 15th is the first partial transmission 7th downstream. The second partial coupling 19th the powershift clutch 15th is the second partial transmission 9 downstream. By means of the partial transmission 7th , 9 of the transmission 1 speed steps can be engaged, for example by means of the first partial transmission 7th odd speed steps and by means of the second sub-transmission 9 straight speed steps and possibly a reverse gear. To change the driving steps or gears of the transmission 1 can the partial couplings 17th , 19th the powershift clutch 15th are alternately closed or opened.

The partial transmissions 7th , 9 is a common transmission output shaft 21st downstream, by means of the drive wheels of the motor vehicle 5 are drivable.

Between the powershift clutch 15th and the transmission 1 is a transmission input shaft 23 switched. The transmission input shaft is designed as a double shaft in the form of a hollow shaft, with the first partial coupling between 17th and the first partial transmission 7th an inner shaft 25th the transmission input shaft 23 and between the second partial coupling 19th and the second partial transmission 9 an outer shaft 27 the transmission input shaft 23 are switched.

On the engine output shaft 13th there is an engine torque 29 Mmot on. The engine torque 29 For example, Mmot can come from the drive source 11 be generated or applied to this as a drag torque. The transmission 1 an output torque 31 Mab up.

The transmission input shaft 23 is on the outer shaft 27 via a housing bearing 33 and the inner shaft 25th via a housing bearing 51 stored on the housing. The outer shaft 27 is against the inner shaft 25th via an interim storage facility 34 stored. On the outer shaft 27 induces the housing bearing 33 an external bearing moment 37 M _{Lager_IPS2_Gehause} . On the inner shaft 25th an external bearing moment acts 53 M _{Lager_IPS_Gehause} . Further acts between the outer shaft 27 and the inner shaft 25th a moment of interim storage 34 M _{Lager_IPS1_IPS2} . The effective direction of the moment depends on which shaft rotates faster.

When engaging or disengaging a gear or a gear, the inner shaft acts 25th a first synchronization moment 39 M _{1_synch} and on the outer _shaft 27 a second synchronization moment 41 M _{2_synch} .

By means of the reference symbols i1 and i2, in 1 the different gear ratios of the partial transmissions 7th and 9 symbolizes.

In addition, the transmission input shaft 23 , which moves in a gear oil, braked due to churning losses, with a first churning torque on the inner shaft 43 M _{1_Öl} and on the outer _shaft 27 a second plan moment 45 M _{2_Oil} is present.

With the power shift clutch open 15th or opened part-load clutches 17th and 19th is due to the first partial coupling 17th a first clutch drag torque 47 M _{1_Kupplung} and on the second partial coupling 19th a second clutch drag torque 49 M _{2_coupling} on.

aufgestellt werden, wobei $${\text{M}}_{1\_\text{Summe}}={\text{M}}_{1\_\text{Kupplung}}-{\text{M}}_{1\_\ddot{\text{O}}\text{l}}-{\text{M}}_{\text{Lager}\_\text{IPS}1\_\text{Geh}\ddot{\text{a}}\text{use}}\pm {\text{M}}_{\text{Lager}\_\text{IPS}1\_\text{IPS}2}\pm {\text{M}}_{1\_\text{synch}}$$

und
J_{Eingangswelle1} ein Trägheitsmoment der Innenwelle 25 sind.The following is an example of the first partial coupling 17th and the inner shaft 25th the transmission input shaft 23 a method for determining the first clutch drag torque 47 M _{1_Kupplung} explained in more detail: For a rotational acceleration of the inner _shaft 25th can the formula $$\mathrm{\omega }{\text{'}}_{\text{Accelerate}}={\text{M.}}_{1\_\text{total}}/{\text{<figure-callout id="1" label="J Input shaft" filenames="DE102011011921B4\_0009.png" state="{{state}}">J</figure-callout>}}_{\text{Input shaft}}$$

be set up, with $${\text{M.}}_{1\_\text{total}}={\text{M.}}_{1\_\text{coupling}}-{\text{M.}}_{1\_\ddot{\text{O}}\text{l}}-{\text{M.}}_{\text{warehouse}\_\text{<figure-callout id="1" label="IPS" filenames="DE102011011921B4\_0009.png" state="{{state}}">IPS</figure-callout>}1\_\text{Go}\ddot{\text{a}}\text{use}}\pm {\text{M.}}_{\text{warehouse}\_\text{<figure-callout id="1" label="IPS" filenames="DE102011011921B4\_0009.png" state="{{state}}">IPS</figure-callout>}1\_\text{IPS}2}\pm {\text{M.}}_{1\_\text{synch}}$$

and
J _{input shaft1} a moment of inertia of the inner _shaft 25th are.

The first plan moment 43 M _{1_Öl} corresponds to the splash losses of the inner shaft 25th that moves in the gear oil, which always has a braking effect. The same applies to that of the housing bearing 51 induced external bearing moment 53 M _{bearing_IPS1_housing} . The bearing between the inner shaft 25th and the outer shaft 27 can have a braking or accelerating effect, so that an internal bearing moment 35 M _{Lager_IPS1_IPS2 has an} accelerating or braking effect, depending on which of the shafts 25th and 27 turns faster. Therefore, depending on the speed ratios of the inner shaft 25th and the outer shaft 27 the transmission input shaft 23 Change of sign occur. The above equation applies at the moment of a gear disengagement by the first partial transmission 7th , with the first partial clutch open 17th the powershift clutch 15th and if a rotational speed of the inner shaft 25th is smaller than a rotational speed of the drive source 11 , so there is a positive speed difference.

wobei $${\text{M}}_{1\_\text{Summe}}={\text{M}}_{1\_\text{Kupplung}}-{\text{M}}_{1\_\ddot{\text{O}}\text{l}}-{\text{M}}_{\text{Lager}\_\text{IPS}1\_\text{Geh}\ddot{\text{a}}\text{use}}\pm {\text{M}}_{\text{Lager}\_\text{IPS}1\_\text{IPS}2}\pm {\text{M}}_{1\_\text{synch}}$$

In the event of a negative speed difference, i.e. if the speed of the motor output shaft 13th the drive source 11 is less than the speed of the inner shaft 25th the transmission input shaft 23 , applies: $$\mathrm{\omega }{\text{'}}_{\text{Accelerate}}={\text{M.}}_{1\_\text{total}}/{\text{<figure-callout id="1" label="J Input shaft" filenames="DE102011011921B4\_0009.png" state="{{state}}">J</figure-callout>}}_{\text{Input shaft}}$$

in which $${\text{M.}}_{1\_\text{total}}={\text{M.}}_{1\_\text{coupling}}-{\text{M.}}_{1\_\ddot{\text{O}}\text{l}}-{\text{M.}}_{\text{warehouse}\_\text{<figure-callout id="1" label="IPS" filenames="DE102011011921B4\_0009.png" state="{{state}}">IPS</figure-callout>}1\_\text{Go}\ddot{\text{a}}\text{use}}\pm {\text{M.}}_{\text{warehouse}\_\text{<figure-callout id="1" label="IPS" filenames="DE102011011921B4\_0009.png" state="{{state}}">IPS</figure-callout>}1\_\text{IPS}2}\pm {\text{M.}}_{1\_\text{synch}}$$

berechnen lässt.Both gradients or rotational accelerations can advantageously be compared with one another, so that the first clutch drag torque is achieved 47 M _{1_Coupling of} the first partial coupling 17th the powershift clutch 15th according to the formula $${\text{<figure-callout id="1" label="J Input shaft" filenames="DE102011011921B4\_0009.png" state="{{state}}">J</figure-callout>}}_{\text{Input shaft}}*\left(\left|\mathrm{\omega }{\text{'}}_{\text{Delay}\ddot{\text{O}}\text{gladly}}\right|+\left|\mathrm{\omega }{\text{'}}_{\text{Accelerate}}\right|\right)/2={\text{M.}}_{1\_\text{coupling}}$$

can calculate.

Alternatively and / or additionally, a temperature influence can be taken into account. In principle, a calculation of the sum torque M _{1_Summe includes} frictional and loss _torques , for example due to the viscosity of lubricating oils and greases. These influences can advantageously be taken into account by means of the temperature model.

Alternatively and / or additionally it is possible to use the method several times, that is to say to use angular accelerations from preselection shifts occurring one after the other and / or different directions, for example a shifting process of the first partial transmission 7th of the transmission 1 from a first gear to a neutral position and to a third gear and then back, that is, from the third gear to a neutral position to a first gear.

Taking into account the temperature of the gearbox 1 can for example by means of a corresponding sensor device 55 , for example by means of a temperature sensor and / or a transmission temperature model.

Alternatively and / or additionally, it is conceivable to use the synchronization torques 39 and 41 _Exclude M _{1_Synch} , M _{2_synch} , the method being able to be carried out in a neutral position, where M _{1_synch} and M _{2_synch} = 0 can be set.

Alternatively and / or additionally it is conceivable to use a driving strategy and / or a control and / or regulating strategy of the transmission 1 adapt so that comparatively longer neutral phases occur by the respective inactive sub-transmission 7th , 9 of the transmission 1 can be monitored with the method according to the invention.

Alternatively and / or additionally, it is conceivable to use maximum permissible clutch drag torques 47 , 49 M _{1_Kupplung} , M _{2_Kupplung predetermine} or define, it being possible to calculate limit values for maximum angular accelerations or angular _{decelerations} from these. In the event that the limit values of the clutch drag torques and / or the angular accelerations are exceeded, this can advantageously be used as an indicator for displaying the power shift clutch 15th or specifically their first partial coupling 17th or second partial coupling 19th and / or the corresponding sub-transmission 7th , 9 of the transmission 1 be used.

As an alternative and / or in addition, measures can then be taken in a different direction without a preselection switch.

According to the invention, a method is specified which enables the first clutch drag torque 47 M _{1_Kupplung} and the second clutch _{drag torque} 49 _Detect M _{2_clutch} . The basis for this is the previously described equation of motion for the transmission input shaft 23 or, for example, the inner shaft 25th the transmission input shaft 23 . For the outer shaft 27 the transmission input shaft 23 the procedure can be carried out analogously. In the event that a clutch drag torque 47 , 49 is recognized, in particular if this exceeds a limit value, this can be taken into account in a transmission control, for example for a temperature model, for degradation and / or for initiating an emergency run and / or for displaying the transmission.

List of reference symbols

1

transmission

3

Drive train

5

Motor vehicle

7th

first partial transmission

9

second partial transmission

11

Drive source

13

Engine output shaft

15th

Powershift clutch

17th

first partial coupling

19th

second partial coupling

21st

Transmission output shaft

23

Transmission input shaft

25th

Inner shaft

27

Outer shaft

29

Engine torque

31

Output torque

33

Housing bearing outer shaft

34

Intermediate bearing outer shaft against inner shaft

35

internal bearing moment

37

external bearing moment

39

Internal shaft synchronization torque

41

Synchronization torque outer shaft

43

Transverse torque inner shaft

45

Transverse torque outer shaft

47

Drag torque of the first partial clutch

49

Drag torque of the second partial clutch

51

Inner shaft housing bearing

53

external bearing moment

55

Sensor device

Claims (8)

Method for monitoring a clutch, in particular a powershift clutch (15) of a drive train (3) of a motor vehicle (5), the clutch (15) being preceded by an engine output shaft (13) and a transmission input shaft (23) of a transmission (1) of the drive train (3) ) is connected downstream, with the following steps: - keeping the clutch (15) open, - determining a rotational acceleration variable characterizing the rotational acceleration behavior of the transmission input shaft (23) of the transmission (1) ((ω ' _accelerate , ω' _retard ), - disengaging or disengaging a gear of the transmission (1), - twice determining the angular acceleration variable ((ω ' _accelerate , ω' _decelerating ) for a positive and for a negative speed difference between the engine output shaft (13) and the transmission input shaft (23), - determining a clutch drag torque (47,49 ) as a function of the twice determined angular acceleration variable ((ω ' _accelerate , ω' _decelerate ) using the formula: $${\text{M.}}_{\text{coupling}}={\text{J}}_{\text{Input shaft}}*\left(\left|\mathrm{\omega }{\text{'}}_{\text{Delay}}\right|+\left|\mathrm{\omega }{\text{'}}_{\text{Accelerate}}\right|\right)/\mathrm{2,}$$

where M _{clutch is} the clutch drag torque, J _{input shaft is} a mass moment of inertia of the transmission _input shaft (23), ω ' _decelerates a determined or determinable rotational acceleration of the transmission _input shaft (23) at a negative speed difference between the engine output shaft (13) and the transmission _input shaft (23) and ω' _accelerates a Determined or determinable rotational acceleration of the transmission input shaft (23) at a positive speed difference between the engine output shaft (13) and the transmission input shaft (23) are characterized by : - determining a temperature of the transmission (1), - determining the clutch drag torque (47, 49) in addition depending on the temperature. Method according to the preceding claim, characterized by : determining the angular acceleration variable ((ω ' _accelerate , ω' _decelerate ) by means of a sensor device (55) assigned to the transmission input shaft (23). Method according to one of the preceding claims, characterized by : - determining the angular acceleration variable ((ω ' _accelerate , ω' _decelerate ) as angular acceleration. Method according to one of the preceding claims, characterized by : - determining the clutch drag torque (47, 49) during a neutral phase of the transmission (1). Method according to one of the preceding claims, characterized by : multiple implementation of the method for different gear changes of the transmission (1), in particular in different directions. Method according to one of the preceding claims, characterized by at least one, some or each of the following steps: - setting a threshold value for the clutch drag torque (47, 49), - displaying the clutch (15) if the determined clutch drag torque (47; 49) is the Exceeds the threshold value, - initiation of protective measures based on the determined clutch drag torque, - initiation of degradation measures based on the determined clutch drag torque. Method according to one of the preceding claims, characterized in that the transmission (1) is a partial transmission (7, 9) of a double clutch transmission. Transmission (1), in particular double clutch transmission, set up to carry out a method according to one of the preceding claims.

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