DE102017100927A1 - Method for adapting a touch point of a friction clutch - Google Patents

Abstract

The invention relates to a method for adapting a touch point of a friction clutch, which in an automated clutch actuation system (1) is driven by a hydrostatic actuator (3) in which the touch point is adapted from a pressure-displacement curve by means of the pressure (p), from which a clamping force-distance relation correlated with a transmitted clutch torque (T) is determined. In a method in which a starting operation can be carried out smoothly, in a clamping region (C) of the friction clutch (9) upstream, a clearance of the friction clutch (9) comprising region (B) of the friction clutch (9) is a reliably detectable reference pressure signal ( D) is generated and after detection of the reference pressure signal (D) a Tastpunktadaption without observation of the clutch torque (T) in this area (B) is performed.

Description

The invention relates to a method for adapting a touch point of a friction clutch, which is driven in an automated clutch system by a hydrostatic actuator in which the touch point from a pressure-displacement curve is adapted by means of the pressure, resulting in a correlated with a transmitted clutch torque Klemmkraft- Way relation is determined.

In automated clutch systems with hydrostatic actuators, beyond an estimated clutch torque, a pressure in the hydraulic system as a direct measured variable is an important information transmitter, which can significantly increase the torque accuracy. For directly operated clutches, a pressure or an estimated clamp pressure or clamping force characteristic is used to determine the clutch torque directly via a friction factor. A directly actuated clutch is understood to be a clutch in which a lever transmitter, which is connected upstream of a transmission ratio of the clutch, is dispensed with.

From the DE 10 2012 204 940 A1 a method for the adaptation of parameters of a clutch is known which comprises a hydrostatic clutch actuator with a pressure sensor in a motor vehicle. In this method, in particular the touch point is calculated from the pressure signal and adapted. The clutch control comprises a hydrostatic path and is controlled by means of adaptive algorithms. Slow changes in the pressure-displacement hysteresis and also the slope of the clamping pressure or clamping force characteristic are learned in principle via an observer. At the same time, the touch point is adapted relatively quickly via a displacement of the path-pressure characteristic. This is done via a direct comparison of the pressure curve with the measurement result of the pressure sensor. The clutch torque is then determined with directly actuated clutches on the estimated force curve and a friction factor. In these considerations, it is assumed that either the touch point between two adaptation phases changes only slightly or the touch point can be learned with sufficiently small clutch torques, so that the adaptation of a larger deviation for the driver is not noticeable.

In particular, when using hydrostatic actuators, the hydrostatic distance can shift within a minute by a noticeable amount. The learning in only one region of the clutch, where the clamping force is active, has the disadvantage that the adaptation takes place too late to ensure a jerk or delay-free approach or Ankriechvorgang of the vehicle when the characteristic shift already exceeded a certain amount Has. The driver thus takes a moment reaction was.

Under the clamping force of the clutch is to be understood in the context of this document, the force at which abut the pressure plates of the clutch on the clutch disc and reliably transmit a clutch torque. In this area, the coupling system can not be observed on the pressure side, which is why no touch point can be learned in this area. For this reason, the pressure in the clutch system is often compensated by a snooping operation, which in turn can lead to driving losses, since for a certain time the clutch is not available.

The invention has for its object to provide a method for adapting a touch point of a friction clutch, in which a reliable characteristic shift is detected even when driving or Ankriechvorgang of the vehicle.

According to the invention the object is achieved in that in a clamping region upstream, a clearance of the friction clutch comprehensive region of the friction clutch, a reference pressure signal is generated and after detection of the reference pressure signal a Tastpunktadaption is performed without observation of the clutch torque in this area. The use of the reference pressure signal has the advantage that a touch point adaptation can already be carried out in this region of the friction clutch which lies in front of the clamping region, which results in ensuring a jerk-free and delay-free approach of the vehicle at all times.

Advantageously, the reliably detectable reference pressure signal exceeds interfering signals occurring in the area encompassing the clearance of the friction clutch. Since the signal-to-noise ratio is extremely unfavorable in this range which encompasses the clearance, no adaptation of the touch point has hitherto been carried out in this area. Only the introduction of the reference pressure signal allows a Tastpunktadaption in this area.

In one embodiment, the reference pressure signal is in an approximately constant relationship to the pressure occurring in the clamping region of the friction clutch. Because of this constant ratio, the touch point shift is significantly recognizable, which is particularly advantageous in wet-running clutches, where there is little wear and the diaphragm spring is a nearly constant pressure offset.

In one variant, a constructive element in the clearance of the friction clutch is used to generate the reference pressure signal. This The constructive element is struck against the clutch cover and, within the range of the friction clutch comprising the clearance, results in a constant travel offset being set relative to the clamping force line.

In one embodiment, the constructive element fastened on one side to the coupling has a constant displacement offset relative to a clamping force characteristic curve occurring in the clamping region of the friction clutch. This ensures that the tactile point can be reliably adapted even without the need for a moment balance.

In one embodiment, a learning area defined by the constant path offset within which the touch point adaptation is carried out is formed within the clearance of the friction clutch area. In this case, the area of the friction clutch which encompasses the clearance is subdivided into an actual release area, to which the learning area adjoins. The learning area for the touch point adaptation is directly upstream of the clamping area of the friction clutch and leads to a smooth transition of the touch point adaptation of the area encompassing the clearance to the clamping area, without the driver noticing.

In a particularly simple embodiment, a spring element is used as the constructive element. Such a spring element inherently has a constant path offset, which can be easily used in the touch point adaptation within the range encompassing the clearance.

Advantageously, the reference pressure signal has a predetermined signature. By means of this signature, it is simplified for an observer to recognize this reference pressure signal and to carry out the touch point adaptation on this basis.

In one embodiment, the predetermined signature of the reference pressure signal comprises a stage. One stage represents a particularly meaningful reference signal in order to be reliably recognized by the observer.

In one embodiment, the level of the signature of the reference pressure signal is generated by a stop of the structural element. By using the stop of the constructive element is sufficiently recognized in front of the terminal area, so that a key of this pressure level unnoticed by the driver in both the inactive clutch, but also a stand-open clutch is possible.

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

• 1 einen schematischen Aufbau eines hydrostatischen Kupplungsbetätigungssystems,
• 2 ein Ausführungsbeispiel einer Messeinrichtung zur Durchführung des erfindungsgemäßen Verfahrens,
• 3 eine Prinzipdarstellung einer Druck-Weg-Kennlinie eines hydrostatischen Kupplungsbetätigungssystems,
• 4 ein Ausführungsbeispiel einer Tastpunkt- oder Kennlinienverschiebung in einem hydrostatischen Kupplungsbetätigungssystem nach dem Stand der Technik,
• 5 ein Prinzipablauf des erfindungsgemäßen Verfahrens,
• 6 ein Reibungskupplungsmodell zur Durchführung des erfindungsgemäßen Verfahrens,
• 7 ein Ausführungsbeispiel einer Druck-Weg-Kennlinie nach dem erfindungsgemäßen Verfahren,
• 8 ein zweites Ausführungsbeispiel einer Druck-Weg-Kennlinie nach dem erfindungsgemäßen Verfahren.

Show it:

• 1 a schematic structure of a hydrostatic clutch actuation system,
• 2 an embodiment of a measuring device for carrying out the method according to the invention,
• 3 a schematic representation of a pressure-displacement curve of a hydrostatic clutch actuation system,
• 4 an embodiment of a Tastpunkt- or characteristic shift in a hydrostatic clutch actuation system according to the prior art,
• 5 a principle sequence of the method according to the invention,
• 6 a friction clutch model for carrying out the method according to the invention,
• 7 An embodiment of a pressure-displacement curve according to the inventive method,
• 8th A second embodiment of a pressure-displacement curve according to the inventive method.

In 1 schematically is the structure of a hydrostatic clutch actuation system 1 with a hydrostatic clutch actuator 3 shown how this is used in vehicles. The hydrostatic clutch actuation system 1 includes a controller 2 , which is the hydrostatic clutch actuator 3 controls. When the position of the clutch actuator changes 3 becomes a piston 4 a master cylinder 5 moved along an actuator path to the right, the volume in the master cylinder 5 changed and a pressure p in the master cylinder 5 is built. This pressure p is via a hydraulic fluid 6 , which serves as a pressure medium, via a hydraulic line 7 to a slave cylinder 8th transferring the friction clutch 9 directly operated. The friction clutch 9 is referred to as a directly operated clutch, since the operation takes place without the interposition of a lever spring. The pressure p of the hydraulic fluid 6 causes it in the slave cylinder 8th a change of direction, resulting in the operation of the friction clutch 9 reflected.

The pressure p is in the master cylinder 5 by means of a pressure measuring device 10 determined with the control unit 2 connected is. The of the clutch actuator 3 traveled distance s is from a displacement sensor 11 certainly. The one of the clutch actuator 3 distance traveled s is further with the way the friction clutch 9 equated.

For touch point adaptation, which takes place during operation of the motor vehicle, is in the control unit 2 a general observer 12 filed, which the real existing clutch actuation system 1 is connected in parallel ( 2 ). The observer 12 comprises a control technology model 13 which is the real clutch actuation system 1 replicates. The real clutch actuation system 1 as well as the model 13 become the same input variables as, for example, the path s, which is the clutch actuator 3 when operating the friction clutch 9 travels, fed. Through the pressure measuring device 10 the actual measured pressure p _mess is measured in the hydraulic path, wherein the clutch torque T _{mess is determined} from an engine torque and a speed gradient. The measured pressure p _mess and the calculated clutch torque Tmess are in a summation point 14 with one through the model 13 described pressure p _model and that through the model 13 calculated clutch torque T _model compared. For both parameters p, T, in each case a pressure difference Δp or a moment difference ΔT is formed which is based on a model correction unit 15 be guided, which determines a corresponding correction of the touch point .DELTA.TP, the model 13 is forwarded.

In 3 an embodiment of a pressure-displacement characteristic is shown, as described by the described observer 12 is seen. The path s divides into three areas, in which the pressure characteristic also expands. In the as refill area A designated area becomes a sniffer hole 16 The hydrostatic range of the clutch actuation system 1 with a storage container 17 connects, open, with the pressure p of the hydraulic fluid 6 can be compensated in the hydrostatic section ( 1 ).

At this refill area A closes the clearance of the friction clutch 9 comprehensive area B inside, within which the clearance of the friction clutch 9 is overcome. This means that the hydrostatic actuator 3 the clutch actuation system 1 Although moving, but no moment through the friction clutch 9 is transmitted. To the area B closes a clamping area C on, in which the clamping force is active and in which the friction clutch 9 a moment transmits. The clamping pressure is proportional to the clamping force with which the clutch disc through the friction clutch 9 is detected. The clamping force is in turn proportional to the clutch torque T.

As from the schematic diagram in 4 shows, at a Tastpunktverschiebung .DELTA.TP the characteristic only in the terminal area C postponed. In the refill area A as well as in which the clearance of the friction clutch 9 comprehensive area B According to the prior art, no touch point shift takes place.

5 shows a schematic diagram of a Tastpunktermittlung according to the inventive method. The dashed line represents the original pressure characteristic. It becomes a reference pressure signal D within the pressure signal p in the range B introduced the Lüftspiels, which the signal fluctuations, the pressure signal p in these areas A . B has exceeded. Such a reference pressure signal D For example, by a sensor spring 18 generated at the friction clutch 9 , in particular the clutch cover 19 is firmly anchored and has a finite length. Through this sensor spring 18 an increasing pressure offset is introduced. The arrow P1 indicates the threshold of the signal fluctuations P4. By the observer 12 can this reference pressure signal D sufficiently clear within the range B be detected. The clearance of the friction clutch 9 comprehensive area B divided with introduction of the sensor spring 18 in a lift-off area B1 and a sensor area B2, whereby the raising of the level of the pressure signal p via the reference pressure signal in the sensor area B2. Starting from the detection of the pressure threshold by the observer 12 comes with this reference pressure signal D introduced a new learning threshold Ln for the touch point. The old learning threshold La of the touch point is marked with the arrow P2. By lowering the new learning threshold Ln compared to the old learning threshold La, it is possible to carry out a touch-point adaptation already in the lift-off process and the characteristic, correspondingly even before the friction clutch 9 begins to transmit a moment to move. This is indicated by arrow P3.

In 6 an equivalent circuit diagram for the new clutch model to be used is shown. The pressure p acts on the pressure pot 20 and the hydraulic fluid 6 , what by the spring 21 referred to as. The pressure pot 20 is over a plate spring 22 with the clutch cover 19 connected to which a pad spring 23 attached, which is opposite to the hydraulic fluid 6 and the pressure pot 20 has a clearance LS. According to the invention is now on the clutch cover 19 arranged the sensor spring 18. This sensor spring 18 may have a free end.

Reduces this axial model on a friction clutch 9 and on the relevant stiffnesses, you get the in 7 illustrated configuration. This configuration corresponds to the pressure-displacement curve shown under alt. Add now, as in 6 explains, the sensor spring 18 finite length added in this clearance LS and reduces the Belleville spring force 22 accordingly, that turns out to be one under newly marked pressure-path characteristic. This characteristic now includes the mentioned properties in order to detect a characteristic shift in the clearance LS and to perform a touch-point adaptation.

As an extension, a sensor spring with stop can be introduced, which is a step-shaped pressure change of the reference pressure signal D in the clearance LS corresponds, as it in 8th is shown. This stepped form 24 the reference pressure signal D needs less air gap and offers an even better path resolution. Due to its design, it also has less displacement tolerance than the free sensor spring 16 , In this form, care must be taken that the height of the step exceeds the learning threshold from the lift-off level, in order to adapt the touch point directly to this step 24 to allow.

This sensor spring with stop but can also be sufficiently recognized in front of the clamping area C, so that a key of this pressure level unnoticed by the driver on the inactive friction clutch 9 or standing with the friction clutch open 9 is possible.

LIST OF REFERENCE NUMBERS

1

hydrostatic clutch actuation system

2

control unit

3

Hydrostatic clutch actuator

4

piston

5

Master cylinder

6

hydraulic fluid

7

hydraulic line

8th

slave cylinder

9

friction clutch

10

Pressure measuring device

11

displacement sensor

12

observer

13

model

14

summing

15

Model correction unit

16

sniffing hole

17

reservoir

18

sensor spring

19

clutch cover

20

pressure cooker

21

feather

22

Belleville spring

23

lining spring

24

Leap

A

Refill area

B

a clearance of the friction clutch comprehensive range

C

clamping range

D

Reference pressure signal

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 102012204940 A1 [0003]

Claims (10)

Method for adapting a touch point of a friction clutch, which in an automated clutch actuation system (1) by a hydrostatic actuator (3) is adapted, in which the touch point from a pressure-displacement curve by means of the pressure (p) is adapted, resulting in a with a transmitted clutch torque (T) correlating clamping force-distance relation is determined, characterized in that in a clamping region (C) of the friction clutch (9) upstream, a clearance of the friction clutch (9) comprehensive range (B) of the friction clutch (9) a reliably detectable reference pressure signal (D) is generated and after detection of the reference pressure signal (D) a Tastpunktadaption without observation of the clutch torque (T) in this area (B) is performed. Method according to Claim 1 , characterized in that the reliably detectable reference pressure signal (D) in the clearance of the friction clutch (9) comprising region (B) occurring interference exceeds. Method according to Claim 1 or 2 , characterized in that the reference pressure signal (D) is in an approximately constant ratio to the pressure (p) occurring in the clamping region (C) in the friction clutch (9). Method according to Claim 1 . 2 or 3 , characterized in that for generating the reference pressure signal (D), a constructive element (18) in the clearance (LS) of the friction clutch (9) is used. Method according to Claim 4 , characterized in that on the friction clutch (9) unilaterally mounted constructive element (18) has a constant displacement offset relative to a clamping force in the clamping region (C) of the friction clutch (9) occurring. Method according to Claim 4 or 5 , characterized in that within the clearance (LS) of the friction clutch (9) comprehensive area (B) is formed by the constant path offset certain learning area (B2), within which the Tastpunktadaption is performed. Method according to at least one of the preceding claims, characterized in that a spring element (18) is used as the constructive element. Method according to at least one of the preceding claims, characterized in that the reference pressure signal (D) has a predetermined signature. Method according to Claim 8 , characterized in that the predetermined signature of the reference pressure signal (D) comprises a stage (24). Method according to Claim 9 , characterized in that the step of the signature of the reference pressure signal (D) is generated by a stop of the structural element.

Images