DE112011102078B4 - METHOD OF CONTROLLING AN AUTOMATED DUAL CLUTCH - Google Patents

Abstract

Method for controlling an automated double clutch (4) with at least two partial clutches, each of which is actuated via a hydrostatic actuator (10; 20), a change in the control of one of the partial clutches being used to control another partial clutch, characterized in that a change is used when driving an active partial clutch for driving an inactive partial clutch, so that the control quality of the inactive partial clutch is kept at a high level without sniffing.

Description

The invention relates to a method for controlling an automated double clutch with at least two partial clutches, each of which is actuated via a hydrostatic actuator.

DE 10 2005 041 420 A1 discloses adapting clutch parameters after sniffing by resetting the parameters.

WO 2007/124 710 A1 discloses a method which provides for measuring the slip at both clutches during a crossover shift. The slip values are measured in a time grid to be specified and converted into a clutch error value by comparing the controlled total clutch torque with the total clutch torque determined from engine data.

DE 10 2008 043 384 A1 discloses a method for adapting the characteristic curves of an automated double-clutch transmission.

From the German Offenlegungsschrift DE 10 2008 057 656 A1 a clutch system with an automated friction clutch with a hydraulic clutch release system is known, which is actuated by an actuator controlled by a control unit. A decision as to whether a sniffing process should be carried out at very low detuning rates depends on operating parameters such as speed changes or temperature changes.

The object of the invention is to improve the control quality of an automated double clutch with at least two partial clutches, each of which is actuated via a hydrostatic actuator.

This object is achieved by a method having the features of claim 1.

The object is achieved in a method for controlling an automated double clutch with at least two partial clutches, each of which is actuated via a hydrostatic actuator, in that a change in the control of one of the partial clutches is used to control another partial clutch. When using hydrostatic actuators, the relatively large coefficient of volumetric expansion of the hydrostatic fluids used can result in the relationship between a master piston travel and a slave piston travel shifting when the temperature changes. The slave piston travel determines the engagement travel and the clutch torque of the respective partial clutch. Such temperature-related shifts can be detected or determined with the aid of sensors and/or a drive train observer. A detected or determined displacement can then be taken into account the next time the clutch is activated. In the context of the present invention, it was found that a change in the control of a first partial clutch can be used when controlling a second partial clutch in order to improve the control quality of the second partial clutch. This provides the advantage that there is no need to detect and determine a temperature-related displacement of the second partial clutch. This is particularly advantageous when detecting and determining a temperature-related displacement of the second partial clutch is operationally not possible because the second partial clutch is, for example, inactive or open, that is, does not transmit any torque.

According to the invention, it is provided that a change in the activation of an active partial clutch is used to activate an inactive partial clutch. The active partial clutch is closed so that it transmits torque. The inactive partial clutch is open so that it does not transmit any torque.

Another preferred exemplary embodiment of the method is characterized in that an adaptation of one of the partial clutches is used to adapt another partial clutch. It is possible to carry out the same adaptation for both partial clutches. In the context of the present invention, however, it has proven to be advantageous to make an adjustment when adapting the other partial clutch. Differences in the actuators of the two partial clutches are taken into account during the adjustment.

A further preferred exemplary embodiment of the method is characterized in that a map shift of one of the partial clutches is used for a map shift of another partial clutch. The map shifts mainly result from the thermal expansion of the hydrostatic fluid.

A further preferred exemplary embodiment of the method is characterized in that a touch point shift of one of the partial clutches is used for a touch point shift of another partial clutch. In this case, the touch point displacement of the other partial clutch is preferably adapted to specific differences in the actuators of the two partial clutches.

A further preferred exemplary embodiment of the method is characterized in that a change in the encoder travel of one of the partial kup plungen is used to change the encoder travel of another sub-clutch. As a result, the number of sniffing processes required during operation can be significantly reduced.

A further preferred exemplary embodiment of the method is characterized in that geometric differences in the hydrostatic actuators or actuators are taken into account when the partial clutches are actuated. The geometric differences include, for example, slave piston areas, dead volumes in the slave piston and line lengths in the hydrostatics. The resulting differences can be determined, for example, by calculations.

A further preferred exemplary embodiment of the method is characterized in that cross-adaptation is carried out when the partial clutches are activated. On the one hand, the cross-adaptation can significantly improve the control quality of the other, in particular the inactive clutch. In addition, the number of sniffing processes required during operation can be significantly reduced.

A further preferred exemplary embodiment of the method is characterized in that cross-adaptation with adaptation parameters is carried out when the partial clutches are activated. The adjustment parameters preferably take into account geometric differences in the hydrostatic actuators or actuators.

A further preferred exemplary embodiment of the method is characterized in that the partial clutches are actuated directly via the hydrostatic actuators, each with a master cylinder and a slave cylinder. The partial clutches are preferably directly actuated or pressed clutches. The clutches are preferably designed as dry friction clutches, but can also be designed to run wet, for example in a multi-plate design.

• 1 ein Kupplungsbetätigungssystem zur Betätigung einer automatisierten Doppelkupplung und
• 2 zwei kartesische Koordinatendiagramme, in denen die Temperatur und der Tastpunkt beziehungsweise Geberweg über der Zeit aufgetragen sind.

Further advantages, features and details of the invention result from the following description, in which various exemplary embodiments are described in detail with reference to the drawing. Show it:

• 1 a clutch actuation system for operating an automated double clutch and
• 2 two Cartesian coordinate diagrams in which the temperature and the touch point or encoder travel are plotted over time.

In 1 a clutch actuation system 1 for an automated dual clutch 4 is shown in a greatly simplified manner. The double clutch 4 comprises two partial clutches and is arranged in a drive train of a motor vehicle between at least one engine and a transmission. The two partial clutches of the double clutch 4 are preferably designed as pressed-on friction clutches. However, the sub-clutches can also be designed as wet clutches. The two partial clutches of the dual clutch 4 are actuated directly by the clutch actuation system 1 .

The two partial clutches of the double clutch 4 are arranged in a clutch bell housing 5, which is indicated by a dashed rectangle. Each partial clutch of the dual clutch 4 is a hydrostatic clutch actuator 10; 20 associated with a clutch master 11; 21 includes. The clutch master 11; 21 each comprise a master cylinder in which a master piston can be moved back and forth. The movement of the master piston is controlled by the clutch actuator 10; 20 initiated.

The clutch master 11; 21 are together with the clutch actuators 10; 20 outside of the clutch bell 5 arranged. About hydrostatic or hydraulic pressure lines, the clutch master 11; 21 each with a clutch slave 12; 22 hydraulically or hydrostatically connected. The clutch slave 12; 22 are arranged inside the clutch bell housing 5 and each comprise a slave cylinder in which a slave piston is guided so that it can be moved back and forth. The slave piston actuates the respective sub-clutch of double clutch 4, for example with the interposition of a bearing and a lever spring or disk spring.

The master cylinder of the clutch master 11; 21 can each be connected to a compensating tank 30 via a connecting opening, which is also referred to as a snifting opening, and via a connecting line 25 . During operation of the double clutch 4, a volume equalization of the fluid volume closed in the hydrostatic system is carried out via the open snifting opening. When a snifting process is carried out, the respective master piston in the master cylinder is pulled back to such an extent that the snifting opening is released and pressure can be equalized in the equalizing tank 30 . As a result, ambient pressure sets in inside the hydrostatic system and the actuators become powerless.

When the master pistons move in the direction of actuation, i.e. in 1 down, the respective sniffer opening is closed. With further movement of the master piston in the pressure builds up in the hydrostatic system in the same direction. This pressure build-up is hydraulically or hydrostatically by the respective clutch master 11; 21 to the associated clutch slave 12; 22 transmitted in order to press the respective sub-clutch of the double clutch 4.

The clutch actuators 10; 20 are each via an electric motor actuator with an actuator motor 14; 24 and can be driven with an actuator gear. About the transmission is a rotary drive motion of the actuator motors 14; 24 converted into a longitudinal movement or translational movement of the master piston.

Arrows indicate that the actuator motors 14; 24 via actuator electronics 41; 42 can be controlled. The actuator electronics 41; 42 is in turn controlled by a drive train control unit 50, as indicated by additional arrows.

The clutch master 11; 21 and the clutch slave 12; 22 contain hydrostatic fluid such as brake fluid or oil. The hydrostatic fluid has a relatively large coefficient of expansion, which depends on the temperature.

The temperature-related expansion of the hydrostatic fluid during operation of the dual clutch 4 causes a shift in the relationship between the master piston travel and the slave piston travel. The slave piston travel determines the engagement travel and the clutch torque of the respective partial clutch.

With the respectively active, ie closed, partial clutch, which transmits a torque, the shift in the relationship between the master piston travel and the slave piston travel can be recognized and adapted in slip phases. Especially if you drive in one gear for a long time, there can be significant temperature changes in the hydrostatic fluid and thus significant map shifts. Additional signals, such as the hydrostatic pressure, can also be used for the adaptation.

With the inactive, ie open, partial clutch, which does not transmit any torque, it is not easy to adapt. An engagement force signal, for example in the form of a pressure signal, is also not helpful here, since the course of the engagement force of the open clutch is rather flat.

Since sniffing is carried out with the clutches closed and the clutch open, it is possible to carry out frequent sniffing processes in order to bring the hydrostatic volume to a known value. However, frequent sniffing processes can lead to delays in reacting to shift requests, which has a negative effect on driving comfort.

The invention provides a way of significantly increasing the time spans in which the respective inactive partial clutch can be kept at a standby point without sniffing. It is assumed that the temperatures in the hydrostatic clutch actuators, which are assigned to the two partial clutches, do not differ greatly.

From this point of view, it is advantageous if the clutch slave 12; 22 are accommodated in a common slave cylinder arrangement or double cylinder arrangement. Furthermore, it is advantageous if the pressure lines, which the clutch slave 12; 22 with the clutch masters 11; 21 connect, run together or close together through the clutch bell housing 5 or the transmission. The clutch master 11; 21 are advantageously also installed close together.

According to a further aspect of the invention, it is assumed that shifts in the characteristics map that occur during operation when the hydrostatic clutch is actuated mainly result from the thermal expansion of the hydrostatic fluid. It is therefore proposed that the characteristic field shift of the respectively active partial clutch be used to infer the characteristic field shift of the respectively inactive partial clutch. The thermal expansion of the hydrostatic fluid is taken into account in a cross adaptation.

According to a further aspect of the invention, however, shifts in the characteristics map are not taken over from the active to the inactive sub-clutch without adaptation. In practice, the actuator systems of the two partial clutches can have minor differences, for example in terms of geometry. The slave piston surfaces can vary in size due to the manufacturing process. Depending on their design, the slave cylinders or pistons can have dead volumes of different sizes. The cable lengths for connecting the clutch slave to the clutch master can vary. The differences between the actuator systems can be determined, for example, by calculations.

According to a further aspect of the invention, it is taken into account that the proportions of fluid in the clutch master and in the clutch slave have a different ratio in the case of the active partial clutch than in the case of the inactive partial clutch. Other differences result, for example, from the fact that the temperatures at the clutch slaves differ from the temperatures at the clutch masters the. Corresponding factors for the cross-adaptation can be determined, for example, by measurements.

$$\Delta {\text{x}}_{2\text{\_inact}}={\text{f}}_2\cdot \Delta {\text{x}}_{\text{1\_act}}$$

Cross-adaptation parameters f ₁ , f ₂ to f _n result from the calculations and/or measurements. The following formula then results for the characteristic field shifts or contact point shifts Δx of the double clutch 4: $$\Delta {\text{x}}_{1\text{\_inact}}={\text{f}}_1\cdot \Delta {\text{x}}_{\text{2\_act}}$$

$$\Delta {\text{x}}_{2\text{\_inact}}={\text{f}}_2\cdot \Delta {\text{x}}_{\text{1\_act}}$$

The inactive partial clutch is then controlled with the determined Δx values. The transmitter position is changed in such a way that a desired air gap is maintained. The next time the affected partial clutch is activated, the required clutch torque can be approached more precisely.

In 2 are two Cartesian coordinate diagrams 60; 70 each with an x-axis 61; 71 and a y-axis 62; 72 shown one above the other. The temperature of the hydrostatic fluid is plotted against time in the form of a characteristic curve 65 in the coordinate system 60 . Below this, in the coordinate system 70, the contact point or sensor travel of a partial clutch is plotted over time in the form of a characteristic curve 75.

Two dashed lines 76, 77 indicate a range that can be tolerated with regard to the control quality of the partial clutch. A further dashed line 78 indicates a limit for an adapted transmitter travel or touch point. At limit 78, an undesired occurrence of drag torques is taken into account.

In 2 shows how a map shift of the active partial clutch determined by adaptation can be used as a measure for the map shift of the inactive partial clutch. With a suitable pilot control, the control quality of the inactive partial clutch can be kept at a high level for the next shift for longer without sniffing.

Reference List

1

clutch actuation system

4

Double coupling

5

clutch bell

10

clutch actuator

11

clutch master

12

clutch slave

14

actuator motor

20

clutch actuator

21

clutch master

22

clutch slave

24

actuator motor

25

connection line

30

surge tank

41

actuator electronics

42

actuator electronics

50

powertrain control unit

60

Cartesian coordinate diagram

61

X axis

62

y-axis

65

curve

70

Cartesian coordinate diagram

71

X axis

72

y-axis

75

curve

76

dashed line

77

dashed line

78

dashed line

Claims (9)

Method for controlling an automated double clutch (4) with at least two partial clutches, which are each actuated via a hydrostatic actuator (10; 20), a change in the control of one of the partial clutches being used to control another partial clutch, characterized in that a change is used when driving an active partial clutch for driving an inactive partial clutch, so that the control quality of the inactive partial clutch is kept at a high level without sniffing. procedure after claim 1 , characterized in that an adaptation of one of the partial clutches is used for an adaptation of another partial clutch. Method according to one of the preceding claims, characterized in that a characteristic field shift of one of the part clutches is used for a characteristic field shift of another part clutch. Method according to one of the preceding claims, characterized in that a Touch point shift of one of the sub-clutches is used for a touch point shift of another sub-clutch. Method according to one of the preceding claims, characterized in that a change in the master travel of one of the partial clutches is used to change the master travel of another partial clutch. Method according to one of the preceding claims, characterized in that geometric differences in the hydrostatic actuators (10; 20) or actuators are taken into account when the partial clutches are actuated. Method according to one of the preceding claims, characterized in that cross-adaptation is carried out when the partial clutches are actuated. Method according to one of the preceding claims, characterized in that cross-adaptation with adaptation parameters is carried out when the partial clutches are activated. Method according to one of the preceding claims, characterized in that the partial clutches are actuated directly via the hydrostatic actuators (10; 20) each with a master cylinder and a slave cylinder.

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