DE102017209983A1 - Method for calibrating a hydraulic actuator of a switchable clutch and control unit - Google Patents

Abstract

The invention relates to a method for calibrating a hydraulic actuator of a switchable clutch, wherein a supply of hydraulic fluid to the actuator is controlled according to a stored characteristic. Subsequently, it is determined whether the clutch has been closed according to a specification, wherein the characteristic curve is not corrected in the specification of appropriate closing of the clutch. In this case, the characteristic curve reproduces the profile of a setpoint pressure over a setpoint time. In order to be able to realize a reliable calibration with a low outlay, a reference parameter is observed and it is checked whether a reaction of the reference parameter takes place within the supply controlled according to the characteristic curve within a defined time window. If the reaction of the reference parameter does not occur within the time window, the setpoint time of the characteristic curve is changed.

Description

The invention relates to a method for calibrating a hydraulic actuator of a switchable clutch, wherein a supply of hydraulic fluid is controlled to the actuator according to a stored characteristic, wherein it is subsequently determined whether the clutch of a specification has been closed accordingly, and wherein not in the specification accordingly Closing the clutch the characteristic curve is corrected. Furthermore, the invention relates to a control device, a computer program product and a data carrier comprising this computer program product.

In a drive train of a motor vehicle with a drive machine designed as an internal combustion engine, the drive machine is usually connected via an intermediate starting element to the following components of the drive train. If an automatic transmission or an automated motor vehicle transmission is also provided in the drive train, an actuation of the starting element is usually carried out automatically, that is to say an opening and closing of the starting element is controlled via a corresponding control. If the starting element is also a switchable coupling with hydraulic actuating device, it is usually necessary to regulate the filling of the actuating device of the coupling in the context of regulating the opening and closing of the coupling. This is to be designed in this case with regard to a suitable actuation of the clutch and thus an involvement of the drive machine so that a filling does not take place too slowly and thus an integration of the drive machine is completed only with a long reaction time. On the other hand, the filling and thus the closing of the clutch may not be designed too fast, as it would come in the episode to noticeable blows in the drive train, resulting in a corresponding reduction in comfort would result. For this reason, the most accurate possible calibration of a hydraulic actuator of a switchable coupling is necessary.

In the DE 197 39 215 A1 It is described in the introduction that calibration of a hydraulic actuating device of a shiftable clutch can take place, inter alia, by initially filling with a low filling pressure and then observing an engine speed of an engine to detect proper operation of the clutch. Specifically, the observed engine speed is compared to a known engine speed, and in the event that the engine speed does not vary by a predetermined amount, the fill pressure is progressively changed until a change in engine speed has occurred in the sense of the known engine speed. The thus determined filling pressure is then stored in a memory of a controller of the clutch.

Starting from the above-described prior art, it is now the object of the present invention to realize a method for calibrating a hydraulic actuator of a switchable clutch, wherein the calibration is to be carried out in a reliable manner at the same time low effort.

This object is achieved from a procedural point of view, starting from the preamble of the independent claim 1 in conjunction with its characterizing features. From a device technical point of view, a solution of the problem by the technical teaching of the independent claim 8. The subsequent thereto, each dependent claims give each advantageous developments of the invention again. Finally, claim 10 also has a computer program product, as well as claim 11, a data carrier having this computer program product.

According to the invention, in a method for calibrating a hydraulic actuating device of a shiftable clutch, a filling with hydraulic fluid is regulated in accordance with a stored characteristic curve, wherein it is subsequently determined whether the clutch has been correspondingly closed to a specification. If a non-compliant closing of the clutch is detected, the characteristic is corrected.

In the context of the method, therefore, a hydraulic actuating device is calibrated, wherein the actuating device is provided for the actuation of a switchable coupling. In a particularly preferred manner, this actuating device comprises, in a manner known to those skilled in the art, an actuating piston which is moved counter to a restoring spring element when pressure is applied during the filling of an associated pressure chamber. The actuating piston then acts in particular mechanically on the clutch and actuates it.

In principle, the shiftable clutch can be in the form of a clutch that is open or closed in the unactuated state. In the former case, a transfer to a closed state is initiated with filling of the respective pressure chamber with hydraulic fluid, while the clutch is in the absence of pressurization in an open state. In contrast, one is in the unactuated state closed clutch in the absence of pressurization, a closed state of the clutch before, ie only with filling of the pressure chamber and concomitant pressurization, the clutch is transferred to an open state. By "closing" the clutch is meant in the context of the invention that coupling halves of the clutch are coupled together in the course of closing, so that set the same speeds or substantially equal speeds between the coupling halves. However, the coupling is particularly preferably in the form of a clutch that is open in the unactuated state.

In the context of the invention, the shiftable clutch is designed in particular as a non-positive clutch and more preferably as a friction clutch, such as a multi-plate clutch. Furthermore, the shiftable clutch is, in particular, a shifting element of a motor vehicle transmission, this shifting element, apart from the shifting of gears of the motor vehicle transmission, also being used to display start-up processes of the motor vehicle. Alternatively, the switchable clutch may also be a starting element of a drive train of a motor vehicle, which is placed between a drive machine and a motor vehicle transmission in the drive train.

In the context of the invention, it is determined in the method for calibrating whether the clutch has been correspondingly closed to a specification, wherein the characteristic curve is corrected in the event of not being given the appropriate closing. According to the invention, control of the hydraulic actuating device is then checked in the connection, whether a desired closing of the associated clutch has taken place. If this is not the case, the control of the supply of hydraulic fluid to the actuator for the next closing of the clutch is changed. This is realized in the sense of the invention in that the characteristic stored in a memory curve is corrected accordingly, so that takes place in a following on the current closing of the clutch closing the supply of hydraulic fluid to the actuator with the corrected characteristic.

The invention now according to the independent claim 1, the technical teaching that the characteristic reflects the course of a desired pressure over a target time. As a default, a reference parameter is observed and it is checked whether a reaction of the reference parameter takes place in the supply controlled according to the characteristic within a defined time window. If a reaction of the reference parameter remains within the time window, the setpoint time of the characteristic curve is changed.

In other words, a characteristic is thus prescribed for the regulation of the supply of hydraulic fluid to the actuating device, in which values of a desired pressure are plotted as a function of values of a desired time. In the course of the calibration, a desired actuation of the clutch is thereby determined by observing a reference parameter which shows a response to an actuation of the clutch. If this reaction takes place within a defined time window, this is declared as a proper actuation of the clutch. On the other hand, if the reaction does not take place, a change in the setpoint time of the characteristic curve is made in the course of the method according to the invention.

Such a configuration of a method for calibrating a hydraulic actuating device of a switchable clutch has the advantage that a supply of hydraulic fluid of the actuating device can be adapted in a simple manner so that a closing of the switchable clutch is not too fast but not too slow , Because by observing the reference parameter and checking whether a reaction of the reference parameter takes place within the desired time window, it can be detected whether the regulation of the actuating device and thus also the activation of the switchable clutch are carried out as intended. By changing the setpoint time of the characteristic curve, a correction can be realized in a simple manner in the event that an unscheduled closing of the switchable clutch is performed in the currently predetermined characteristic curve of the actuating device.

In contrast, at the DE 197 39 215 A1 made a change in the desired pressure, wherein the target pressure is changed until the engine speed changes to the expected extent. The change in the desired pressure is more complex.

The "reference parameter" is preferably a parameter which is influenced by the closing of the switchable clutch. At the same time, the closing of the coupling should be clearly recognized on the basis of the reference parameter.

If the shiftable clutch is a clutch that is open in the unactuated state, filling of a pressure chamber of the hydraulic actuating device is predetermined by the characteristic curve. On the other hand, if the shiftable clutch is in the form of a clutch that is closed in the unactuated state, an emptying of a pressure chamber of the hydraulic actuating device is carried out on the basis of the characteristic curve.

The characteristic curve gives a profile of the setpoint pressure over the setpoint time, ie with which pressure as a function of time the supply of hydraulic fluid to the actuating device of the shiftable clutch is completed. If, according to the invention, it is now recognized on the basis of the observed reference parameter that the clutch has not been closed as planned, the setpoint time is modified. In this case, a modification of the characteristic curve takes place in particular in an area in which a supply of hydraulic fluid takes place with an extreme value of the desired pressure, ie when filling either with a maximum pressure or when emptying with a minimum pressure. It is therefore preferred to change the time duration which is decisive for the filling or emptying.

In this case, a time range is selected as the time window after the start of the regulation corresponding to the characteristic curve, in which case a reaction of the reference parameter is to be expected in the event of a desired closing of the shiftable clutch. In this case, a first time window is preferably first predetermined, in which no reaction of the reference parameter should take place, since otherwise there would be a too fast closing of the switchable clutch and, as a result, comfort-reducing shocks would occur in the respective drive train. Only then does a second time window, which is decisive for the observation of the reference parameter, begin.

According to an embodiment of the invention, in case the reaction of the reference parameter takes place before the time window, the target time is shortened. However, if the reaction of the reference parameter occurs only after the time window, the setpoint time is extended. In an advantageous manner, the supply of hydraulic fluid to the actuating device can thus be changed by appropriate modification of the target time such that a closing of the shiftable clutch takes place in the desired time window.

In a further development of the invention, a motor torque of a drive machine is observed as reference parameter, which is integrated via the clutch in a drive train. Closing of the clutch is therefore in this case concluded that an engine torque of a prime mover is tracked, which is to be integrated via the switchable clutch. Because the engine torque will show a reaction in the form of a torque peak when closing the clutch and the associated involvement of the prime mover. The observation of the engine torque has the advantage that the reaction to the closing of the clutch is very high resolution. Alternatively, it would also be conceivable within the scope of the invention to observe a different reference parameter, such as, for example, an engine speed of the engine.

According to a further embodiment possibility of the invention, the calibration is carried out during operation. In other words, the method according to the invention thus finds application in the course of the use of the shiftable clutch in the respective drive train, so that a calibration based on the actual conditions of use is possible here. Compared to a calibration, which is carried out at the end of a mounting of the shiftable clutch, this has the advantage that the actual circumstances can be taken into account. In addition, the wear of the switchable clutch can thereby be taken into account during operation. According to the invention, however, the calibration can also be carried out alternatively or additionally to the end of the assembly of the shiftable clutch.

In a further development of the invention, the calibration is performed only when the reaction of the reference parameter is present as a change with a certain gradient. This ensures that only a significant change of the reference parameter is detected as a reaction and thus there is no fault detection of a closing of the shiftable clutch. Within the scope of the invention, empirical values are to be oriented which represent a behavior of the reference parameter in the case of a proper closing of the clutch. In the case of observation of an engine torque of an engine, a minimum gradient in the range of 5 to 15 Nm / s must be particularly preferred.

It is a further embodiment of the invention that the calibration is performed only when at least one constraint has been met. This has the advantage that thus further criteria can be taken into account, which are a prerequisite for a suitable calibration. Thus, the calibration is preferably carried out only if the function for calibration by a driver has been activated. It must therefore be the permission of a driver to perform the calibration of the actuator at all.

Alternatively or in addition to the calibration takes place only when a speed of a prime mover, which is integrated via the shiftable clutch in a drive train, during the supply of hydraulic fluid is substantially constant and varies only by a predefined value. Further alternatively or additionally, during the calibration, a specific engine speed band of the engine may not be left, which is preferably in a range of 1200 to 1500 U / min.

As a further supplementary or alternative boundary condition may also be required that a certain temperature of the hydraulic fluid is maintained. The reason for this is that the viscosity of the hydraulic fluid changes depending on the temperature. In particular, a temperature of the hydraulic fluid in the range of 50 ° C is required.

Another possibility for a boundary condition, which can be taken into account as a supplement or as an alternative to the aforementioned, is that a specific gear or gear range must be engaged in a transmission of the drive train. Thus, it may be required that in a motor vehicle transmission of the respective drive train, a low gear is selected, as higher gears and thus also associated higher speeds can lead due to inertia to other detectable parameters. Finally, it can be specified as a further possible boundary condition that a roadway on which the respective motor vehicle is located should be as level as possible.

According to a further embodiment of the invention, a change of the target time is completed step by step. At the appropriate for a proper closing of the switchable clutch target time is thus keyed in several steps by the time is changed stepwise. Time steps in the range of 10 ms to 100 ms are particularly preferably carried out here.

The invention also relates to a control unit, which is in particular a clutch or transmission control unit. In this case, this control device comprises a device for regulating a calibration of a hydraulic actuating device of at least one switchable clutch, wherein an actuation of the at least one clutch can be represented by controlling a supply of hydraulic fluid to the actuating device according to a characteristic. The characteristic curve reflects the course of a setpoint pressure over a setpoint time. The device of the control device is designed to determine in the course of the calibration whether a clutch corresponding to a specification has taken place by the device observing a reference parameter and thereby checks whether in accordance with the characteristic regulated supply within a defined time window a Reaction of the reference parameter takes place. If there remains a reaction of the reference parameter within the time window, the device changes the setpoint time of the characteristic curve. Within a motor vehicle, this control unit is then integrated into a data bus system and is in exchange with other control units in order to obtain, for example, information about the reference parameter.

The solution according to the invention can also be embodied as a computer program product which, when running on a processor of a control unit, instructs the processor by software to carry out the associated process steps according to the invention. In this context, a computer-readable medium is the subject of the invention, on which a computer program product described above is stored retrievably.

The invention is not limited to the specified combination of the features of the independent or the dependent claims. It also results in ways to combine individual features, even if they emerge from the claims, the following description of a preferred embodiment of the invention or directly from the drawings. The reference of the claims to the drawings by use of reference numerals is not intended to limit the scope of the claims.

• 1 eine schematische Ansicht eines Antriebsstranges eines Kraftfahrzeuges;
• 2 ein Ablaufdiagramm eines Verfahrens zum Betreiben einer Betätigungseinrichtung im Antriebsstrang aus 1, entsprechend einer bevorzugten Ausführungsform der Erfindung;
• 3 ein Diagramm;
• 4 ein weiteres Diagramm; und
• 5 ein weiteres Diagramm.

An advantageous embodiment of the invention, which will be explained below, is shown in the drawings. It shows:

• 1 a schematic view of a drive train of a motor vehicle;
• 2 a flowchart of a method for operating an actuator in the drive train 1 , according to a preferred embodiment of the invention;
• 3 a diagram;
• 4 another diagram; and
• 5 another diagram.

1 shows a schematic view of a drive train 1 a motor vehicle, which is preferably an agricultural or municipal utility vehicle and this in particular is a farm tractor. The powertrain 1 includes a prime mover 2 , which is designed as an internal combustion engine and on a driven side with a downstream motor vehicle transmission 3 connected is. The motor vehicle transmission 3 is designed in group construction and consists of a load switching part 4 and a synchronous part 5 together.

As further in 1 can be seen, is the motor vehicle transmission 3 on the output side with an axle drive 6 a drive axle 7 connected, via the axle drive 6 one about the motor vehicle transmission 3 translated drive movement of prime mover 2 on two drive wheels 8th and 9 the drive axle 7 is distributed.

The prime mover 2 and also the motor vehicle transmission 3 is ever a control unit 10 respectively. 11 associated with other - not shown here - control devices in a data bus system twelve of the motor vehicle are integrated and can communicate with each other here. In the present case is via the control unit 10 the prime mover 2 regulated while the controller 11 in the motor vehicle transmission 3 the load switching part 4 and the synchronous part 5 regulates. While in the synchronous part 5 between different gear ratios can only be changed under traction interruption, is a change between ratios of the load switching part 4 possible under load.

For this purpose are the load switching part 4 several non-positive switching elements in the form of switchable couplings provided as in 1 by way of example with reference to a coupling 13 shown. The clutches are preferably present as multi-plate clutches and can each be closed via one respective associated hydraulic actuator, as in the case of the clutch 13 via the actuating device 14 , About the control unit 11 can be a respective closing of the respective clutch 13 be made by the controller 11 a supply of hydraulic fluid to the respective associated actuator 14 which subsequently closes the associated clutch 13 initiates. The couplings of the load switching part 4 act at least occasionally as start-up elements in the course of the startup of the motor vehicle, the connection between the prime mover 2 and the motor vehicle transmission 3 produce.

The present only schematically illustrated actuator 14 comprises in principle known in the art a pressure piston, which is acted upon by filling a pressure chamber with pressure and transferred in the sequence against a restoring spring element in an operating position in which the clutch 13 is transferred via the pressure piston in the closed state.

As a special feature is now on the controller 11 the possibility of the respective associated actuator 14 the respective clutch 13 to calibrate during operation and thus to close the respective clutch 13 after activation via the actuating device 14 in a suitable time window. The procedure for calibration of the actuator 14 is here as a flowchart in 2 represented, which represents a preferred variant of the method.

As in 2 can be seen, at the beginning of the method, first in a step S1, a filling of the pressure chamber of the actuator 14 according to a stored characteristic 15 made, which the course of a target pressure p _should over a target time t _shall reproduces. This characteristic 15 is in the diagrams of the 3 to 5 each shown, in which also each a course 16 an engine torque T _Mot and a course 17 an actual pressure p _is are shown. Subsequent to step S1, in a step S2 the course 16 the engine torque T _Mot the prime mover 2 queried, this information to the control unit 11 via the data bus system twelve from the control unit 10 is made available.

Following step S2, it is then queried in a step S3 whether various boundary conditions exist for a calibration. Thus, on the one hand it is queried whether a calibration function is activated at all by a corresponding command from a vehicle driver of the motor vehicle. If that is the case, the boundary condition is considered fulfilled. Furthermore, it is also queried whether a rotational speed of the prime mover 2 during filling has been constant, the speed may vary only by a small value. A preferred speed range here is a speed of 1200 to 1500 U / min. This information is given to the control unit 11 via the data bus system twelve from the control unit 10 the prime mover 2 ,

It is also queried how high a temperature of the actuator 14 supplied hydraulic fluid, in which case a certain temperature range, preferably in the range of 50 ° C, has to exist. In addition, a roadway on which the motor vehicle is currently located should be as level as possible.

Are all the boundary conditions of step S3 fulfilled, so becomes a step S4 otherwise no calibration is made and returned before step S1. In step S4 then becomes the course of the engine torque T _Mot on a reaction to a clutch closing 13 checked, with a torque peak 18 is sought, which must have a minimum gradient. Preferably, a gradient of 5 to 15 Nm / s must be present. Following is then in one step S5 Checks when the torque peak 18 occurred during the filling according to the characteristic curve.

Following this, in one step S6 queried whether the torque peak 18 within a time window t2 has occurred, which is directly on a time window t1 follows. There is the time window t1 a period of time after filling over the characteristic again, within which a closing of the clutch 13 would be too early. On the other hand is a closing of the clutch 13 within the time window t2 optimal.

Will in step S6 realized that the torque peak 18 within the time window t2 occurred, so is a change in the characteristic 15 not necessary and it may be before step S1 be jumped back. The state of a scheduled closing of the clutch 13 is in the diagram in 3 shown.

On the other hand, in step S6, the result is that the torque peak 18 not within the time window t2 lies, is in one step S7 first queried whether the torque peak 18 before the time window t2 took place. This circumstance is in the diagram in 4 to see where the torque peak 18 clearly before the time window t2 and also before the time window t1 lies. Is the result in step S7 positive, so it goes to a step S8, in which in the sequence the characteristic 15 is modified. This will be a time duration t _fill , in which a filling with a maximum pressure p _Max takes place, shortened in this case and then jumped back before step S1.

If the result in step S7 is negative, it can be assumed that the torque peak 18 after the time window t2 lies as in diagram in 5 shown. As a result, in a step S9, the time duration _tfill is then extended and then also jumped back in step S1 before step S1.

After jumping back before step S1 is at a further closing of the clutch 13 Once again a calibration process is started, if then still or for the first time the boundary conditions in step S3 are fulfilled. In the steps S8 and S9 This will be an extension or shortening of the time t _fill performed in single steps of 10 to 100 ms. In the course of a repeated passage of the calibration, this can lead to an optimum characteristic curve for filling the actuating device 14 and thus to close the clutch 13 be felt.

By means of the method according to the invention for calibrating a hydraulic actuating device, this calibration can be realized with little effort and also during operation.

LIST OF REFERENCE NUMBERS

1

powertrain

2

prime mover

3

Motor vehicle transmission

4

Load switching part

5

synchronous part

6

transaxles

7

drive axle

8th

drive wheel

9

drive wheel

10

control unit

11

control unit

12

data bus system

13

clutch

14

actuator

15

curve

16

course

17

course

18

torque peak

p _should

Target pressure

t _shall

Target time

T _Mot

engine torque

p _is

Actual pressure

t _fill

time

p _Max

print

t1

Time window

t2

Time window

S1-S9

individual steps

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 19739215 A1 [0003, 0014]

Claims (11)

Method for calibrating a hydraulic actuating device (14) of a switchable clutch (13), wherein a supply of hydraulic fluid to the actuating device (14) is controlled in accordance with a stored characteristic (15), wherein it is subsequently determined whether the clutch (13) is a default was correspondingly closed, and in which the characteristic curve (15) is not corrected when the appropriate closing of the clutch (13) is corrected, characterized in that the characteristic curve (15) shows the course of a desired pressure (p _soll ) over a desired time ( t _soll ) shows that a reference parameter is observed and it is checked whether in the according to the characteristic (15) controlled supply within a defined time window (t2) takes place a reaction of the reference parameter, and that within the time window (t2) lack of response of the reference parameter the target time (t _soll) of the characteristic curve (15) is changed. Method according to Claim 1 , characterized in that for the case that the reaction of the reference parameter before the time window (t2) takes place, the target time (t _soll ) is shortened, whereas the target time (t _soll ) at a time after the time window (t2 ) reaction of the reference parameter is prolonged. Method according to Claim 1 or 2 , characterized in that as a reference parameter, an engine torque (T _Mot ) of a drive machine (2) is observed, which is involved in a drive train (1) via the clutch (13). Method according to one of Claims 1 to 3 , characterized in that the calibration is performed during operation. Method according to one of the preceding claims, characterized in that the calibration is performed only if the reaction of the reference parameter is present as a change with a certain gradient. Method according to one of the preceding claims, characterized in that the calibration is performed only if at least one boundary condition has been met. Method according to one of the preceding claims, characterized in that a change in the setpoint time (t _soll ) is completed step by step. Control unit (11), in particular a clutch or transmission control unit, comprising a device for regulating a calibration of a hydraulic actuating device (14) of at least one switchable clutch (13), wherein closing the at least one clutch (13) by controlling a supply of hydraulic fluid to the Actuating device (14) according to a characteristic curve (15) can be represented, which reflects the course of a desired pressure (p _soll ) over a desired time (t _soll ), wherein the device determines in the course of calibration, whether a closing corresponding to a default the coupling (13) has taken place by the device observing a reference parameter and thereby checking whether, in accordance with the characteristic (15) regulated supply within a defined time window (t2), a reaction of the reference parameter takes place, and wherein the device at within the time window (t2) lack of response of the reference parameter the target time (t _soll ) of the characteristic (15) changed. Control unit (11) to Claim 8 , wherein the device further comprises a method according to one or more of Claims 2 to 7 is feasible. Computer program product for a control unit (11) according to Claim 8 or 9 , by which a method according to one or more of Claims 1 to 7 is feasible, wherein a routine for calibration by corresponding stored in a software control commands is implemented. Disk with a computer program product after Claim 10 ,

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