WO2008028817A1

WO2008028817A1 - Method for detecting the engagement point of a clutch, especially a wet starting clutch

Info

Publication number: WO2008028817A1
Application number: PCT/EP2007/058760
Authority: WO
Inventors: Wolfgang Danz; Horst Schmitter; Wilfrid Eberhard
Original assignee: Zf Friedrichshafen Ag
Priority date: 2006-09-08
Filing date: 2007-08-23
Publication date: 2008-03-13
Also published as: DE102006042356A1

Abstract

In order to detect the engagement point of a clutch, especially a wet starting clutch, at least two methods operating in parallel are used, the detection being deemed successful as soon as one method enables the engagement point to be detected.

Description

Method for detecting the point of contact of a coupling, in particular a wet starting clutch

The present invention relates to a method for detecting the Aniegepunktes a clutch, in particular a wet Anfahrkuppiung, according to the preamble of claim 1.

In a vehicle comprising a transmission, in order to start up or to provide traction in the drive train, a clutch must be engaged, i. torque must be transmitted to the clutch.

In a hydraulically actuated clutch, the force is generated on the clutch via a pressurizable piston according to the prior art, wherein in order to build up the required pressure can befüilt possibly emptied piston chamber and a certain "blind pressure" - caused by springs, friction ... - must be built up before the clutch starts to transmit torque.

In this case, the "blank pressure" varies from vehicle to vehicle and, moreover, it depends on the respective ambient conditions, for example on the temperature, the rotational speed, etc.

With regard to driving comfort, it is of crucial importance to precisely detect the point at which a clutch is just beginning to transmit torque, referred to below as the application point, in order to be able to optimally control or regulate the closing process. In transmissions which have a hydraulic torque converter, according to the prior art, the application point of the clutch is detected on the basis of the influence of the pressure on the converter output rotational speed, whereby the converter output rotational speed kinks when the antege point is reached. However, this procedure is not possible with transmissions which have a starting clutch and no converter.

From EP 0 550 222 B1 a method for determining the point of contact of a friction clutch is known, in which the engine is operated at Leeriaufdrehzahi, the idle position of the transmission is selected, an output of the friction clutch is applied with a predetermined braking torque and the rotational speed of the output shaft the friction clutch is detected. Here, a comparison signal for a speed is first generated, which is lower than the idle speed; then a Differenzdrehzah! formed between the Drehzahlüberieichssignal and the detected speed of the output shaft and the friction clutch is engaged to such a degree that the differential speed is minimized, then the Kupplungsberührpunktsignal the degree of Kuppiungseinrückens is set accordingly when the detected speed of Ausgangsuts the friction clutch within a vorbesfimmten range of the speed comparison signal is.

A method for determining the contact point of a friction clutch is known from EP 0 635 391 B1. Here, the engine is operated at an idle speed, the idle position of the transmission is selected, an output shaft of the friction clutch is supplied with a predetermined brake torque, and a reference speed that is lower than the idling speed is selected. In addition, the rotational speed of the output of the friction clutch is detected to determine the transmission input speed and the friction clutch with a first Einrückmaß engaged, wherein a first degree of Kυppiυngseinrückens is detected when the transmission input speed reaches the reference speed. Then, the coupler is released by varying the engagement amount by a first offset amount from the first acceleration engagement amount and engaged with a second engagement amount smaller than the first dimension, and the clutch touch point is detected when the transmission input rotational speed reaches the reference rotational speed when engaged with the second amount ,

Another touch-point detection method for a clutch is disclosed in US 5,337,868 A.

In addition, from EP 1 437 520 A1 a method for controlling an automatically actuated clutch is known in which the torque to be transmitted is controlled according to a clutch characteristic as a function of the clutch position, the clutch characteristic being corrected to compensate for changes in the coupling behavior. Here, a minimum and a maximum characteristic are generated to adapt the clutch characteristic; a valid, interpolated clutch characteristic, which is adapted to factors influencing the clutch engagement, is calculated by interpolation between the values of the minimum characteristic and the values of the maximum characteristic. In the known method, the contact point of the coupling is also calculated by interpolation of the contact points of the minimum and maximum characteristic curves.

DE 196 52 244 A1 describes a method for controlling or regulating a torque transmission system arranged in a vehicle, within the scope of which the gripping point of the system can be adapted in at least one operating point by at least approaching an actual value of a value that can be stored and used by a control unit , adaptable or adaptable, the value of physical Greifpunkfes is derived directly or indirectly due to measurements or calculations. Preferably, an engagement position is identified as the grip point by the control unit, this value being stored as the value of the grip point.

In this case, the value stored as gripping point can be determined from at least one value of a transmittable clutch torque in at least one predefinable engagement position of the torque transmission system; the value of a transmittable clutch torque and / or a difference of such values can be determined from at least one throw of the Moformomen- tes and / or from a difference of engine torque values.

DE 103 08 699 A1 describes a method for driving a creep torque on a clutch in an automated transmission. In the known method, the time of construction and / or the course of the creeping torque is determined as a function of at least one operating parameter of the vehicle.

DE 102 33 772 A1 describes a method for compensating for deviations in the transmission path of a clutch of a vehicle, in which the gripping point on the clutch is corrected and a dynamic balance is evaluated on the engine during a slip phase to correct the coefficient of friction on the clutch. In the known method, the balance is evaluated at arbitrary times and the respective deviations are separated at the Moformoment and at the clutch torque for each operating condition.

The present invention has for its object to provide a method for detecting the application point of a clutch, in particular a wet starting clutch, which supplies a possible exact result in the shortest possible time. This object is solved by the features of patent claim 1. Further embodiments and advantages of the invention will become apparent from the dependent claims.

Accordingly, it is proposed to use at least two methods for detecting the application point, which run in parallel, the detection being successful as soon as a method detects the antege point.

In one of the methods, the engine speed is observed, as a condition the Fahrpeda!, The engine torque and the engine speed must be constant within a tolerance band a certain time before performing the method.

If these conditions are met, the current engine speed! set to reference speed. The application point of the clutch is detected when there is a significant drop in the engine speed with respect to the reference speed, which is due to the fact that the clutch begins to transmit torque and the engine idler has not yet compensated

Another method for detecting the application point of a clutch is that under the condition that no accelerator pedal is actuated and that engine torque and engine speed are constant within a tolerance band a certain time before performing the method, the static engine torque is observed.

When these conditions are met for the first time, the current engine torque is set as the reference torque and the clutch apply point is detected when there is a significant increase in engine torque with respect to the reference torque, which is due to the fact that the clutch begins to transmit torque and the engine designer must build up more torque to keep the engine speed.

A third method for detecting the application point of a clutch is based on the observation of the dynamic engine torque.

At the beginning of the search of the application point, the current engine torque Mmotref and the current engine speed gradient omegamotpref are stored as reference points.

With these reference points and the equivalent inertia of the motor Jmot a reference clutch torque Mkref is calculated at the beginning of the search of the application point according to the following formula:

Mkref = Mmotref - Jmot ^* omegamotpref

In the following, this equation is used to cyclically calculate the current Mk for the clutch torque, Mmot for the engine torque and omegamotp for the engine speed gradient:

Mk = Mmot - Jmot * omegamotp

According to the invention, the application point is detected when there is a significant increase in the calculated clutch torque Mk with respect to the clutch reference torque Mkref.

If the application point is detected by means of the method according to the invention, it can be cyclically checked whether the clutch is still in engagement, for which purpose the target pressure at the clutch is observed becomes. If this pressure is less than the previously detected and thus known application pressure for a defined time, it is recognized that the clutch is no longer engaged, so that a new filling is required.

Furthermore, the invention provides that, for. B. due to an entry into the emergency program is cyclically checked as a deposit criterion, whether the target pressure for a defined time is smaller than the previously detected and thus known application pressure. If this is the case, it is recognized that the clutch is no longer engaged.

The invention is explained in more detail below by way of example with reference to the attached FIGURE, which represents a flow diagram illustrating the method according to the invention.

At the beginning of the procedure it is checked whether the clutch has to be filled (decision "condition Fiiling") .If this is the case, then it is decided whether the Befuilphase should be initiated or not (decision "Start Fitiing"). If the filling phase is initiated, the application criteria for the methods used are initialized or, if the initialization has already taken place, the application criteria are checked and subsequently evaluated. In this case, the conditions for carrying out the procedures must be fulfilled.

On the one hand, for the methods described initially, this means that the accelerator pedal, the engine torque and the engine speed must be constant within a tolerance band a certain time before the method is carried out. If these conditions are met, the current engine speed is set as the reference speed and the current IV engine torque as the reference torque. On the other hand, the current engine torque (Mmotref) and the current engine speed gradient (omegamotpref) are stored as reference points and a Referenzkuppiungsmoment Mkref according to the following forms! calculated:

Mkref = Mmotref - Jmot ^* omegamotpref.

The application criteria are then checked ("Check application criteria" status) and evaluated ("Evaluate application criteria" status) to set the docking status.

If the filling phase is not active, then the decision "Create" is made, in which, if the coupling has already been created, the transfer criteria are checked cyclically (state "Check transfer criteria") and then evaluated (state "Evaluate skip criteria") In the event that the clutch is not applied and no clutch closure is desired, the Aniegestatus is maintained.

As a deposit criterion is checked whether the target pressure for a defined time is smaller than the previously detected and thus known application pressure. If this is the case, it is recognized that the clutch is no longer engaged. According to the invention, several suitable deposition criteria can be tested in parallel.

According to the invention, at least two methods are used for detecting the application point, which run in parallel, the detection being considered successful as soon as a method detects the application point; d. H. An OR link is provided for detecting the application point. However, it is also possible that two methods are combined via an AND operation.

Although three methods have been described that can be used to detect the point of application, depending on the design conditions Wettere method additionally or alternatively to those already described are used. It is also possible to use only one of the methods described for detecting the application point.

Claims

claims

1. A method for Detektierυng the application point of a clutch, in particular a wet starting clutch, characterized in that for detecting the application point at least two methods are used, which run in parallel, the detection is considered to have occurred as soon as a method defect the Aniegepunkt.

2. A method for detecting the application point of a coupling according to claim 1, characterized in that one of the employable methods comprises the following steps:

Observing the engine speed, wherein as a condition for performing the method the Fahrpedai must not be actuated and engine torque and engine speed must be constant for a certain time before performing the process within a tolerance band, and if these conditions are met, the current engine speed set as the reference speed will and

Detecting the application point of the clutch when there is a significant drop in the engine speed with respect to the reference speed, which is due to the fact that the clutch starts to transmit torque and the engine idling controller has not yet compensated

3. A method for detecting the application point of a coupling according to claim 1 or 2, characterized in that one of the usable methods comprises the following steps; Observing the static engine torque, wherein as a condition for performing the method the Fahrpedai, the engine torque and the engine speed must be constant within a Toferanzbandes a certain time before performing the method, wherein, if these conditions are met, the current engine torque is set as the reference torque and

Detecting the engagement point of the clutch when there is a significant increase in the engine torque with respect to the reference torque, which is due to the fact that the clutch begins to transmit torque and the engine idle controller must build more moment to keep the engine speed.

4. Method for detecting the application point of a coupling according to claim 1, 2 or 3, characterized in that one of the employable methods comprises the following steps

Storing the current engine torque Mmotref and the current engine speed gradient omegamotpref as reference points;

Calculating a reference clutch torque Mkref at the beginning of the implementation of the method according to the following formula:

Mkref = Mmotref - Jmot * omegamofpref,

where Jmot is the equivalent mass inertia of the motor;

Calculate the clutch torque Mk cyclically with the respective current values for the engine torque Mmot and for the engine speed gradient omegamotp according to the following formula: Mk = Mmot - Jmot * omegamotp

and

Detecting the Aniegepunktes when it comes to a significant increase of the calculated clutch torque Mk with respect to the Kupplungsrefer- Renzmomentes Mkref.

5. A method for detecting the Anziehpunktes a clutch according to one of the preceding claims, characterized in that when the Anziehpunkt is detected, it is cyclically checked whether the clutch is still engaged, for which purpose the target pressure of the clutch is observed and wherein, when the clutch pressure for a defined time is less than the previously detected and thus known angling pressure, it is detected that the clutch is no longer engaged.

6. A method for detecting the Anziehpunktes a clutch according to one of the preceding claims, characterized in that, in the event that the Befülfphase is not initiated or canceled, with applied clutch deposition criteria are cyclically checked and then evaluated, in which case that the coupling is not established and no closing of the coupling is desired, the landing status is maintained.

7. A method for detecting the Anziehpunktes a clutch according to claim 6, characterized in that is checked as a deposit criterion, whether the Soildruck for a defined time is smaller than the previously detected and thus known application pressure, which, if so, is detected in that the clutch is no longer engaged. 8, method for detecting the application point of a coupling according to claim 6 or 7, characterized in that several suitable deposition criteria are tested in parallel.