DE102016203624A1 - Method for adapting a clutch model of an automated clutch by adjusting a coefficient of friction of the clutch - Google Patents

Abstract

The invention relates to a method for adapting a clutch model of an automated clutch by adjusting a coefficient of friction of the clutch (5, 6), in which a current coefficient of friction during a slipping phase of the clutch (5, 6) is determined, wherein the adjustment of the coefficient of friction when exceeded a predetermined slip speed threshold (n _S ) by the current slip speed (k _s ) is performed. In a method in which the number of adaptation situations is increased during driving of the vehicle, the slip speed threshold (n _S ) for adjusting the coefficient of friction is changed depending on a status "imprecise speed signals of an internal combustion engine (2) or a transmission input shaft" (9, 10 ) elevated.

Description

The invention relates to a method for adapting a clutch model of an automated clutch by adjusting a coefficient of friction of the clutch, in which a current coefficient of friction during a slipping phase of the clutch is determined, wherein the adjustment of the coefficient of friction is exceeded when exceeding a predetermined slip speed threshold by the current slip speed.

In order to meet the comfort requirements in vehicles always better, a clutch, which is arranged between an internal combustion engine and a transmission and transmits the moment of the internal combustion engine to the power train, must be controlled as precisely as possible. Since the coupling has time-varying properties, for example under the influence of a change in temperature, a coupling model is required, which must be adapted on a regular basis. An adaptation of the coefficient of friction of the clutch model can only be adapted if there is a reliably detectable clutch slip.

The DE 10 2010 024 941 A1 discloses a method of controlling a dual-clutch transmission having two sub-drive trains, each of which is couplable by means of a clutch to an internal combustion engine. When driving the vehicle comprising the dual-clutch transmission, a touch point of the clutch is determined independently of the engine torque. This touch point is therefore determined during commissioning of the vehicle and adapted during operation of the vehicle.

From the WO 2008/064633 A1 For example, a method and apparatus for adapting a hybrid disconnect clutch in a vehicle hybrid powertrain is known in which the engine is shut down and after the engine is shut down, the hybrid disconnect clutch is opened. Subsequently, a time gradient of the speed of the internal combustion engine is detected when the engine and the hybrid disconnect clutch is off. When partially closing the hybrid disconnect clutch, as soon as the engine speed has fallen below a predetermined value, the time gradient of the engine speed in the partially-closed clutch is determined. Subsequently, the characteristic curve of the hybrid disconnect clutch is adapted on the basis of the determined, transmitted from the partially closed hybrid disconnect clutch torque. The clutch characteristic is characterized by a touch point and a coefficient of friction, both of which must be adjusted due to changing conditions of the vehicle and the clutch.

In the event that the speed signals of the engine or the transmission input shaft are not precise, and have, for example, an offset error or a time delay, it may happen that a clutch slip is erroneously detected, although the clutch is in the grip engagement. This finding leads to a misadaptation of the clutch model.

In 3 For example, the common strategy is to clarify the occurrence of a "precise" and "imprecise" status of the engine or transmission input shaft speed signals. The clutch control behaves "precisely" when the signal status is transmitted as described in connection with Section C. The slip speed threshold n _S for the Reibwertanpassung remains untouched in this case. If, on the other hand, as shown in section D, the transmitted signal jam is "imprecise", no friction value adaptation takes place, even if the slip exceeds the range ss in which it is not possible to distinguish reliably between slip and adhesion of the clutch. This is indicated by the adaptation bit b _a equal to zero. This does not happen even if a large slip occurs, which is the case for example when "crawling" the vehicle. This clutch model is blind in this case for each Reibwertänderung. In this case, with a real change in the coefficient of friction, clear coupling model errors occur because the coupling model does not follow the changes. This finally leads to a misjudged clutch torque.

Likewise, due to the status of "imprecise rotational speeds" of the internal combustion engine or transmission input shaft in normal driving situations, many adaptation options for the coefficient of friction remain unused. The coefficient of friction is thus adapted less frequently, which also means that the clutch model is not tracked the changed friction coefficients. Such a misjudged clutch model leads to a deterioration in ride comfort.

The invention has for its object to provide a method for adapting a clutch model of an automated clutch by adjusting a coefficient of friction, in which a coefficient of friction determination by a reliable distinction between a slip and a liability of the clutch is possible.

According to the invention the object is achieved in that the slip speed threshold for adjusting the coefficient of friction in dependence on a status "imprecise speed signals of an internal combustion engine or a transmission input shaft" is increased. The increase in Slip speed threshold ensures that does not have to be dispensed with all adaptation situations, but only those that are below the increased slip speed threshold. By increasing the slip speed threshold a likelihood of confusion of slip and adhesion situations of the clutch is reliably prevented. The slip speed threshold is thereby increased so that it can be safely assumed that the clutch is in a slipping state when the increased slip speed threshold is exceeded by the slip. Thus, even with the status "imprecise speed signals of the internal combustion engine or the transmission input shaft" in which the speeds have, for example, an offset error and / or a time delay, precise clutch torques can be provided, which keeps the ride comfort at a high level.

In one embodiment, the slip speed threshold for adjusting the coefficient of friction as a function of the status "imprecise speed signals of the internal combustion engine or the transmission input shaft" is increased. This supports the situation in which a slip of the clutch is artificially caused and in addition adaptation periods for the clutch model are created.

In one embodiment, the current coefficient of friction is determined by an adjustment of a clutch torque against a moment of the internal combustion engine.

In another embodiment, the friction coefficient adjustment is terminated when the current slip speed falls below the raised slip speed threshold. As a result, the period for adaptation can be reliably limited.

The invention allows numerous embodiments. One of them will be explained in more detail with reference to the figures shown in the drawing.

Show it:

1 a schematic diagram of a dual-clutch transmission,

2 an embodiment of the method according to the invention,

3 an embodiment of the method according to the prior art.

The inventive method is based on the example of a dual clutch transmission 1 be explained. However, this is not a limitation, but can be applied to all possible, having a clutch transmissions.

1 shows a schematic diagram of a dual-clutch transmission 1 , as used in motor vehicles. This dual-clutch transmission 1 is with the internal combustion engine 2 connected and has two sub-strands 3 and 4 on. The connection of a partial string 3 . 4 with the internal combustion engine 2 via a clutch 5 . 6 coming from a control unit 15 be controlled. The first sub-string 3 carries the odd gears 7 while the second substrand 4 the even gears 8th includes. The corridors 7 and 8th are in case of need with a transmission input shaft 9 . 10 a gearbox 11 connected, which has a differential 12 and a drive shaft 13 the drive wheels 14 drives. A speed n _{V of} the internal combustion engine 2 is by a speed sensor 16 detected while a rotational speed n _{G of} the transmission input shaft 9 with a speed sensor 17 is measured. Both speed sensors 16 . 17 are with the control unit 15 connected.

In such a dual-clutch transmission 1 becomes a gear 7 a partial strand 3 with the transmission input shaft 9 connected while the gear 8th of the other branch 4 is inserted. For this purpose, the behavior of the two clutches must 5 . 6 be set precisely to avoid interference. Each of the clutches 5 . 6 is controlled via a clutch model that in the control unit 15 is stored. One parameter of the clutch model is a coefficient of friction, which should be adapted regularly during operation of the vehicle. For adaptation of the coefficient of friction, which at the clutch 5 should be explained, for the clutch 6 but just as true, the clutch works 5 in a slipping state and transmits a clutch torque. This clutch torque is during the slipping phase of the clutch 5 with the moment of the internal combustion engine 2 adjusted and used to determine the coefficient of friction.

Before the friction value adaptation, the engine speed n _V and the transmission input shaft speed n _{G are} evaluated. Is the status of the engine speed n _V or the transmission input speed n _G "precise" ( 2 , Section A), it is assumed that the slip speed range ss, in which the slip of the clutch 5 not reliably detected and with a liability of the clutch 5 can be confused, is very small. If the slip speed k _s exceeds a predetermined slip speed threshold n _S , then an adaptation bit b _{a is} set, which allows the adaptation of the coefficient of friction ( 2a ). The speed n _{K of} the clutch, which is the speed n _{V of} the internal combustion engine 2 corresponds, is in this area above the speed n _{G of} the transmission input shaft 9 , How out 2c shows which the slip of the clutch 5 over the time t, the slip speed range ss in which a slight slip is the clutch 5 occurs and in which a confusion of the slip with a grip engagement of the coupling is possible, very small. Since the slip speed k _s exceeds the slip speed threshold n _S , the coefficient of friction is adapted. The target speed of the slip k _s for the slip request remains unchanged.

Section B shows the behavior of the speeds when the status of either the engine speed n _V or the transmission input speed n _G becomes "imprecise." This means that the rotational speeds have, for example, an offset error and / or a time delay. In this case, since the slip speed range ss in which slippage can not be surely detected increases, the minimum slip speed threshold for adaptations is also increased. For safe setting of a clearly identifiable (sufficiently high) slip, the target slip speed is raised, which in 2c is clarified. If the raised slip speed threshold n _S is exceeded by the current slip speed k _s , the adaptation bit b _a is also set to allow friction coefficient adaptation. At the same time the target slip n _{z is raised} for the friction coefficient adjustment. It follows, as in 2 B illustrated that the slip speed k _{s is increased} over time.

Due to the proposed solution, the coefficient of friction can also be adapted in the status "imprecise speed signals", whereby the clutch model can always follow the changed coefficient of friction characteristics.

LIST OF REFERENCE NUMBERS

1

 Double clutch

2

 internal combustion engine

3

 partial strand

4

 partial strand

5

 clutch

6

 clutch

7

 corridor

8th

 corridor

9

 Transmission input shaft

10

 Transmission input shaft

11

 transmission

12

 differential

13

 drive shaft

14

 drive wheels

15

 control unit

16

 Speed sensor

17

 Speed sensor

n. _V

 Engine speed

n _G

 Transmission input shaft speed

b _a

 Adaptionsbit

n _K

 Coupling speed

n _Z

 target slip

k _s

 Slip speed

n _s

 Slip speed threshold

ss

Slip speed range

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102010024941 A1 [0003]
• WO 2008/064633 A1 [0004]

Claims (4)

Method for adapting a clutch model of an automated clutch by adapting a coefficient of friction of the clutch ( 5 . 6 ), in which a current coefficient of friction during a slipping phase of the clutch ( 5 . 6 ), wherein the adaptation of the coefficient of friction when exceeding a predetermined slip speed threshold (n _S ) by the current slip speed (k _s ) is performed, characterized in that the slip speed threshold (n _s ) for adjusting the coefficient of friction in dependence on a status "imprecise Speed signals of an internal combustion engine ( 2 ) or a transmission input shaft "( 9 . 10 ) is increased. Method according to Claim 1, characterized in that a target rotational speed of the internal combustion engine ( 2 ) for the slip request in dependence on the status "imprecise speed signals of the internal combustion engine ( 2 ) or the transmission input shaft "( 9 . 10 ) is raised. A method according to claim 1 or 2, characterized in that the current coefficient of friction by an adjustment of a clutch torque against a moment of the internal combustion engine ( 2 ) is determined. Method according to at least one of the preceding claims, characterized in that the Reibwertanpassung is terminated when the slip speed (n _K ) falls below the raised slip speed threshold (n _S ).

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