阅读说明：本技术 用于运行机动车动力传动系的离合器的方法以及具有动力传动系的机动车 (Method for operating a clutch of a drive train of a motor vehicle and motor vehicle having a drive train ) 是由 A·比尔克 D·戈特利布 于 2018-03-14 设计创作，主要内容包括：本发明涉及一种用于运行机动车动力传动系(12)的离合器(10)的方法,在其中,借助于动力传动系(12)的电子计算装置(34)有针对性地设定所述离合器(10)的至少一个微滑,由此使离合器(10)在至少一个运行阶段(56、58)期间以微滑运行,其特征在于,借助于电子计算装置(34)有针对性地设定离合器(10)的过压,由此使离合器(10)在与所述至少一个运行阶段(56、58)不同的至少一个第二运行阶段(62、64)期间无打滑地运行。(The invention relates to a method for operating a clutch (10) of a motor vehicle drive train (12), in which at least one creep of the clutch (10) is set in a targeted manner by means of an electronic computing device (34) of the drive train (12), as a result of which the clutch (10) is operated with creep during at least one operating phase (56, 58), characterized in that an overpressure of the clutch (10) is set in a targeted manner by means of the electronic computing device (34), as a result of which the clutch (10) is operated without slippage during at least one second operating phase (62, 64) that differs from the at least one operating phase (56, 58).)

1. A method for operating a clutch (10) of a motor vehicle drive train (12), in which at least one creep of the clutch (10) is set in a targeted manner by means of an electronic computing device (34) of the drive train (12), as a result of which the clutch (10) is operated with creep during at least one operating phase (56, 58), characterized in that an overpressure of the clutch (10) is set in a targeted manner by means of the electronic computing device (34), as a result of which the clutch (10) is operated without creep during at least one second operating phase (62, 64) which differs from the at least one operating phase (56, 58).

2. Method according to claim 1, characterized in that the microslip is adjusted by means of an adjuster (36) of an electronic computing device (34).

3. Method according to claim 2, characterized in that at least one control parameter for controlling the creep is determined in a first operating phase (56, 58), in that a second operating phase (62, 64) is temporally adjacent to the first operating phase (56, 58), in that a further creep of the clutch (10) is set in a targeted manner by means of the electronic computing device (34) immediately adjacent to the second operating phase, as a result of which the clutch (10) is operated with the further creep during a third operating phase (60) which is adjacent to the second operating phase (62, 64), and in that the control parameter determined in the first operating phase (56, 58) is used for controlling the creep during the third operating phase (60).

4. A method according to claim 3, characterized in that a gear change of the transmission (18) of the drive train (12) is performed in a third operating phase (60) immediately adjacent to the second operating phase (62, 64) in which the determined adjustment parameter is used for adjusting the creep.

5. A method according to any one of the foregoing claims, in which the clutch (10) is operated with overpressure during a period outside a gear change phase during which at least one gear change of the transmission (18) of the power train (12) is carried out.

6. Method according to any of the preceding claims, characterized in that the clutch (10) is operated with overpressure during constant travel of the vehicle.

7. Method according to any of the preceding claims, characterized in that the second operating phase (62, 64) is set if at least one parameter changes.

8. A method according to claim 7, characterized in that the parameter comprises the rotational speed of a power plant (14) of the powertrain (12) and/or the torque provided by the power plant (14) and/or the acceleration of the motor vehicle.

9. Method according to one of the preceding claims, characterized in that after the end of the predetermined period of time, the second operating phase (62, 64) is set or terminated accordingly.

10. A motor vehicle having a drive train (12) which is designed to drive the motor vehicle and has at least one clutch (10) and an electronic computing device (34) which is designed to set at least one creep of the clutch (10) in a targeted manner in order to thereby operate the clutch (10) in creep during at least one operating phase (56, 58), characterized in that the electronic computing device (34) is designed to set an overpressure of the clutch (10) in a targeted manner in order to operate the clutch (10) without slippage during at least one second operating phase (62, 64) which is different from the at least one operating phase (56, 58).

Technical Field

The invention relates to a method for operating a clutch of a motor vehicle drive train according to the preamble of claim 1 and to a motor vehicle according to the preamble of claim 10.

Background

DE10150597a1 discloses such a method for operating a clutch, which is used in a drive train of a motor vehicle and is designed, for example, as a friction clutch, and a corresponding motor vehicle. In the method, at least one creep of the clutch is set in a targeted manner/deliberately by means of an electronic computing device of the drive train, as a result of which the clutch is operated with a creep during at least one operating phase. The microslip is clearly explained in DE10150597a 1. A slight slip is to be understood in particular to mean that the input side of the clutch or at least one first structural element of the clutch arranged on the input side of the clutch is rotated at a first rotational speed, while the output side of the clutch or at least one second structural element of the clutch arranged on the output side and drivable by the first structural element is rotated at a second rotational speed, wherein the first rotational speed and the second rotational speed differ slightly from one another. Thus, microslip is very little slip, which is, for example, in the range of 10 to 50 revolutions per minute (inclusive).

In general, a clutch is used as a disconnect clutch to couple and decouple an output shaft of a power unit configured to drive a motor vehicle with and from another shaft, so that torque can be transmitted between the output shaft and the other shaft via the clutch. The further shaft is here, for example, a transmission input shaft of a transmission of the drive train. If a slight slip is set, the output shaft, which is connected, for example, in a rotationally fixed manner, to the input side of the clutch, rotates at a higher or lower rotational speed than the other shaft, which is connected, for example, in a rotationally fixed manner, to the output side of the clutch. The operation of the clutch with low slip can be advantageous for achieving a high level of driving comfort, in particular when shifting a transmission of the drive train.

Furthermore, DE 102013200194 a1 discloses a transmission for a motor vehicle having a drive unit, wherein the transmission comprises a transmission housing and a dual clutch arrangement having a clutch housing. The clutch housing may be connected to the power plant output element, wherein the clutch housing is rotatably mounted in the transmission housing.

Furthermore, DE 102013203513 a1 discloses a method for cooling a multi-speed dual clutch transmission, which is connected to an internal combustion engine in a vehicle.

Disclosure of Invention

The object of the invention is to improve a method and a motor vehicle of the type mentioned at the outset in such a way that a particularly efficient operation can be achieved.

This object is achieved by a method having the features of claim 1 and by a motor vehicle having the features of claim 10. Advantageous embodiments with suitable developments of the invention are specified in the dependent claims.

A first aspect of the invention relates to a method for operating a clutch for a drive train of a motor vehicle, in particular a motor vehicle (e.g. a passenger car), which clutch is designed as a friction clutch, for example. In the method, at least one microslip of the clutch is set in a targeted manner/deliberately by means of an electronic computing device of the drive train, as a result of which the clutch is operated microslip during at least one operating phase. As already explained above, a slight slip is understood to mean a slight slip of the clutch, so that, for example, the input side of the clutch or at least one first structural element of the clutch arranged on the input side rotates at a first rotational speed, and the output side of the clutch or at least one second structural element of the clutch arranged on the output side of the clutch and drivable, for example, by the first structural element rotates at a second rotational speed, which differs slightly from the first rotational speed. The rotational speed difference between the rotational speeds is, for example, in particular in the range from 10 to 100, in particular from 10 to 20, so that the microslip is, for example, in the range from 10 to 100, in particular from 10 to 50, and particularly preferably in the range from 10 to 20.

In order to be able to achieve a particularly high level of driving comfort on the one hand and a particularly efficient and therefore energy-and fuel-efficient operation on the other hand, it is now proposed according to the invention to set the overpressure of the clutch in a targeted manner by means of an electronic computer device, also referred to as a controller, so that the clutch is operated without slipping (without slip) during at least one second operating phase, which is different from the at least one operating phase. The at least one operating phase during which the clutch operates with little slip is also referred to as the first operating phase. In addition, a correspondingly targeted setting of the microslip or the overpressure is to be understood to mean that the microslip or the overpressure is set as desired or intentionally by means of the electronic computing device, so that the microslip or the overpressure is not incidental and not the result of, for example, tolerance occurrences. In order to set the slip or the overpressure in a targeted manner, the clutch, in particular at least one actuating element of the clutch, is actuated, for example, by means of an electronic computing device, in such a way that, for example, at least one, in particular electrical, actuating signal is transmitted from the electronic computing device to the actuating element and is received by the actuating element.

The invention is based on the following recognition, among others: in conventional drivetrains, in particular in conventional transmissions, which are designed, for example, as dual-clutch transmissions, a slight slip of the clutch is usually set during driving. Clutches that are operated with little slip are, for example, so-called active clutches in a dual clutch transmission, which belong to the partial transmissions of the dual clutch transmission and in particular to the engaged gears of the partial transmissions. Here, the drive train generally comprises a drive unit, also referred to as a drive machine, which provides torque for driving the motor vehicle. The drive unit provides a torque, in particular via an output shaft, which is designed, for example, as a crankshaft. A drive unit, in particular an output shaft, which is designed, for example, as an internal combustion engine or as an electric motor, is coupled, in particular, in a rotationally fixed manner, for example, to an input side or a drive side of a clutch or to a first structural element of the clutch, which is arranged on the drive side, in particular in a rotationally fixed manner, such that a torque provided by the drive unit is introduced into the clutch on the input side or the drive side.

The torque provided by the drive unit is at least partially transmitted via the clutch to the output or driven side of the clutch or to a second structural element arranged on the output side, wherein, for example, the output or second structural element is coupled in a rotationally fixed manner to a further shaft, in particular, so that the further shaft, which is configured, for example, as a transmission input shaft of a transmission, can be driven via the clutch by the drive unit, in particular an output shaft. In particular, the output side of the other shaft or of the clutch is driven by the drive unit via the input side in traction mode or in traction, wherein the drive unit provides a torque to drive the other shaft in traction mode or in traction. The corresponding torque is also referred to as drive torque and is, for example, greater than 0 newton meter in traction.

A slight slip is understood here to mean that the input side or output shaft of the clutch rotates several revolutions faster in traction than the output side or other shaft. In overrun mode, in which the output shaft is driven via the clutch by the other shaft, the input side rotates several revolutions slower than the output side, or in the case of inertia.

In this case, for example, the above-mentioned drive torque is less than 0 newton meter. In this case, for example, the rotational speed difference between the input side and the output side is in the range from 10 to 100, in particular from 10 to 50, and preferably from 10 to 20, rpm. The targeted setting of the creep is used on the one hand for a certain degree of disengagement in the drive train, also referred to as drive train, in order, for example, to reduce or attenuate rotational irregularities of the drive unit. On the other hand, the creep is set in a targeted manner for the precise setting of the drive torque at the clutch, for example. In this case, it is to be understood in particular that, for example, a clutch torque of the clutch is set. The clutch torque is a torque which can be transmitted by or through the clutch, for example from the output shaft to the other shaft, or vice versa. For example, the previously mentioned drive torque set precisely at the clutch is understood to mean that the clutch torque is set such that it corresponds to the drive torque provided by the drive unit.

In the event of an overpressure, the clutch is not slipping, i.e. is operated at a slip value of 0 revolutions per minute, so that, for example, the output shaft rotates at the same rotational speed as the other shaft. In the case of an overpressure and therefore a slip value of 0 rpm, the clutch torque, which is related to the drive torque, also referred to as the motor torque, cannot be set. In other words, in the event of an overpressure, the clutch torque cannot or cannot easily be set such that it corresponds to the drive torque, as is well described in DE10150597a1, for example. However, it is advantageous and desirable to set the drive torque precisely at the clutch, in order to set an advantageous clutch torque, in particular as a total torque, for example when a gear change of a transmission of the drive train is carried out or initiated and therefore when the torques concerned overlap, so that a gear change, for example an upshift, can thus be carried out particularly comfortably. If the clutch is closed, for example, before and/or during a gear shift, so that an overpressure of the clutch is present and therefore a slip value of 0 rpm is present, what is known as a lock-up during the aforementioned torque overlap occurs, in particular during a gear shift. This locking is perceived by the occupants of the motor vehicle as a delay, which affects the driving comfort. Thus, the influence on the driving comfort can be avoided by the clutch operating with little slip.

However, the disadvantage of targeted setting of the microslip is that a slip loss results therefrom. With a drive torque of, for example, 200 newton meters and a set microslip of, for example, 15 revolutions per minute, a slip power of about 314 watts is generated. Slip losses not only result in the power in the clutch being converted into heat by friction, but also require additional energy to extract the introduced power and the heat generated thereby.

The method according to the invention now makes it possible to avoid the effects on driving comfort and excessive slip losses, so that particularly comfortable and particularly effective or efficient operation can be achieved. By specifically setting the overpressure such that the slip between the drive side and the output side of the clutch is 0 rpm, slip losses, in particular during driving in or on the constant gear, can be minimized. In order to determine the precise torque point, i.e. the clutch torque which is advantageous for achieving particularly comfortable shifting, also for example when a shift is initiated and when a shift is initiated, for example an upshift or downshift, and to set this torque point or the clutch torque, for example by means of a torque jump, a ramp or a parabola, a first operating phase during which the clutch is operated with little slip is carried out or set. However, in the second operating phase, slip losses are avoided, since the clutch operates without slip.

In order to achieve a particularly comfortable and efficient operation, it is proposed in an advantageous embodiment of the invention that the microslip is set by means of a regulator (closed-loop regulator) of the electronic computing device, in particular during the first operating phase. In other words, the microslip is set and maintained in a regulated manner by means of the electronic computing device, in particular to at least one theoretical value.

In order to achieve a particularly comfortable and efficient operation, it has also been shown to be particularly advantageous to determine at least one control parameter for controlling the creep in the first operating phase. The manipulated variable is also referred to as a manipulated or actuator component. In this case, the second operating phase is immediately adjacent to the first operating phase in terms of time, so that, for example, the clutch is operated first with a slight slip and immediately adjacent thereto with an overpressure. Next to the second operating phase, a further microslip of the clutch is set in a targeted manner by means of the electronic computing device, as a result of which the clutch is operated with the further microslip during a third operating phase which is immediately adjacent in time to the second operating phase.

It is conceivable here that the further microslip or the first value corresponds to the first microslip or the second value, or that their values may differ from one another. In this case, it is provided that, during the third operating phase, the control parameters determined in the first operating phase and stored, for example, in a memory device of the electronic computing device are used to control the microslip.

The first operating phase is therefore, for example, an inspection phase, which is carried out, for example, between operating phases during which the clutch is operated with an overpressure. In particular, it is conceivable here to carry out one or more check phases between two successive operating phases during which the clutch is operated with an overpressure, and to carry out one or more check phases accordingly. During or in the respective test phase, at least one control parameter or a plurality of control parameters is determined as a theoretical slip by the targeted setting of the respective micro slip, wherein, for example, one or more control parameters are stored. Since the microslip is set, in particular by means of the electronic computing device, for example during the respective operating phase or inspection phase, the microslip setting is carried out, in particular during the first operating phase or during the respective inspection phase. This means that the microslip adjustment is performed during a respective examination phase during which at least one or more adjustment parameters are determined.

For example, if the second operating phase is exited or an overpressure is exceeded, one or more control parameters determined before and stored, for example, are used to operate the clutch in a creep mode after it has been operated with an overpressure, and the creep mode is controlled based on the one or more control parameters. For this purpose, for example, the determined control variable itself is used, if appropriate with the aid of a correction value, also referred to as offset value, or combined therewith, in order to correct the previously determined control variable.

In this case, it has been shown to be particularly advantageous to use the determined control parameters for controlling the creep in a third operating phase, which is immediately adjacent to the second operating phase, and to carry out a gear change of the transmission of the drive train in this third operating phase. As described above, particularly comfortable gear changes can be carried out by terminating or removing the overpressure and by using the previously determined control parameters for setting or controlling the creep, without a loss of comfort that is perceptible to the occupants of the motor vehicle occurring.

In order to keep the energy consumption, in particular the fuel consumption, particularly low, a further embodiment of the invention provides that the clutch is operated with excess pressure during a period other than a shift phase during which at least one shift of the transmission is carried out. As a result, slip losses can be avoided, so that a particularly efficient operation can be achieved. Loss of comfort can also be avoided because operation at overpressure does not result in a decrease in comfort.

Another embodiment is characterized in that the clutch is operated with an overpressure during constant driving of the vehicle. During such constant travel, the vehicle travels at an at least substantially constant speed. Since the clutch is operated without slip, excessive slip losses can be avoided, so that a particularly efficient operation can be achieved.

It has proven to be particularly advantageous to set a second operating phase, in particular an inspection phase, if there is a change in at least one parameter which can be specified or defined or definable. For example, the control variable can be adapted to the changed or changing variable, so that, for example, a clutch operation with little slip or a gear change of the transmission, which is carried out in the immediate vicinity of the test phase and in the immediate vicinity of the test phase, respectively, with overpressure, is carried out particularly advantageously and particularly comfortably.

In this case, it has been shown to be particularly advantageous if the parameters comprise the rotational speed of the drive unit, in particular of the output shaft, and/or the torque provided by the drive unit and/or the acceleration of the motor vehicle. Alternatively or additionally, it is advantageous if the second operating phase is set or terminated or exited after the end of the predetermined period of time. By conditionally carrying out the checking phase, the control parameters can always be kept up to date or at favorable values, so that on the one hand a comfortable operation and on the other hand a particularly efficient operation can be achieved. In other words, it is preferably provided that the checking phase is carried out taking into account parameters and boundary conditions (for example motor speed, motor torque and/or vehicle acceleration), which change in particular since the last checking phase, and/or for example as a function of time control, and in particular repeated as many times as necessary. Alternatively or additionally, it is conceivable to interrupt the overpressure or to operate with an overpressure as a function of the parameters mentioned, the clutch operating with little slip, for example, during or after the interruption of the overpressure.

Overall, the method according to the invention makes it possible to keep the time share of the time in which the motor vehicle is operated with a slight slip of the clutch over the total operating time of the motor vehicle particularly small, so that the energy or fuel consumption of the motor vehicle can be kept particularly low. Furthermore, by means of the checking phase and the determination and, for example, storage of the actuator component, a shift quality comparable to conventional creep adjustment can be ensured, so that particularly high driving comfort can be achieved. The method according to the invention is therefore intended to implement the following functions: the fine slip control is replaced by the above-described overpressure as the case may be, so that an increase in efficiency is achieved in comparison to conventional drive trains or transmissions, in particular in dual clutch transmissions, in particular taking into account the boundary conditions of the physical and driving situation.

A second aspect of the invention relates to a motor vehicle, in particular a motor vehicle, for example a passenger car. The motor vehicle has a powertrain configured to drive the motor vehicle, which includes at least one clutch and an electronic computing device. The electronic computing device is designed to set at least one creep of the clutch in a targeted manner in order to thereby operate the clutch in a creep during at least one operating phase.

In order to be able to achieve particularly efficient operation and particularly high driving comfort, the electronic computing device according to the invention is designed to set the overpressure of the clutch in a targeted manner in order to operate the clutch without slip during at least one second operating phase, which is different from the at least one operating phase. The motor vehicle according to the invention is therefore configured to carry out the method according to the invention. The advantages and advantageous embodiments of the first aspect of the invention can be regarded as advantages and advantageous embodiments of the second aspect of the invention and vice versa.

Drawings

Further advantages, features and details of the invention emerge from the following description of a preferred embodiment and with the aid of the drawings. The features and feature combinations mentioned above in the description and those mentioned in the description of the figures and/or shown in the figures only can be used in the combinations indicated above, but also in other combinations or alone without departing from the scope of the invention.

Wherein the content of the first and second substances,

Fig. 1 shows a diagram for explaining a method according to the invention for operating a clutch of a motor vehicle drive train, in which the clutch is operated sometimes with little slip and sometimes under overpressure; and is

Fig. 2 shows a schematic representation of a drive train.

Detailed Description

In the drawings, identical or functionally identical elements are provided with the same reference numerals.

Fig. 1 shows a diagram, by means of which a method for operating a clutch of the drive train 12, which clutch is schematically illustrated in fig. 2 and is designed as a friction clutch 10, is explained below. The drive train 12 is a component of a motor vehicle, which is designed, for example, as a motor vehicle, in particular as a passenger vehicle, and can be driven by means of the drive train 12. For this purpose, the drive train 12 comprises a drive unit 14, which is designed, for example, as an internal combustion engine, in particular as a reciprocating piston internal combustion engine. The drive unit 14 has an output shaft 16, which is designed as a crankshaft, for example, and via which the drive unit 14 can provide a corresponding torque for driving the motor vehicle. The corresponding torque provided by the drive unit 14 via the output shaft 16 is also referred to as motor torque or drive torque.

Furthermore, the drive train 10 comprises at least one transmission 18 via which the wheels 20 of a motor vehicle, in particular of an axle 22 of the drive train 12, can be driven by the drive unit 14, in particular the output shaft 16. For example, the transmission 18 is configured as a dual clutch transmission. The transmission 18 comprises a friction clutch 10, which is also referred to simply as a clutch. In particular, it is conceivable for the transmission 18 to have two clutches, in particular if the transmission 18 is designed as a dual clutch transmission, to which corresponding partial transmissions are assigned. The clutch 10 is in this case one of the clutches of a dual clutch transmission, wherein the above and the following explanations of the clutch 10 can also be easily applied to other possibly provided clutches of a dual clutch transmission, which are not shown in the figures, and vice versa.

As shown in fig. 2, the friction clutch 10 (clutch) has an input side 24 and an output side 26, wherein the input side 24 is also referred to as the drive side. The output side 26 is also referred to as the driven side. For example, output side 26 may be driven by input side 24 and vice versa (i.e., the input side may be driven by the output side). At the input side 24, at least one first structural element 28 of the clutch is arranged, whereas at the output side 26, at least one second structural element 30 of the clutch is arranged. In this case, a corresponding torque can be transmitted between the input side 24 and the output side 26 or between the components 28, 30. Input side 24 or component 28 is coupled, for example, in a rotationally fixed manner, in particular, to output shaft 16, so that input side 24 or component 28 can be driven by output shaft 16, and vice versa. Furthermore, the output side 26 or the structural element 30 is coupled, in particular, in a rotationally fixed manner to a further shaft 32 of the drive train 12, so that, for example, this further shaft 32 can be driven by the output side 26 or the structural element 30, and vice versa. The further shaft 32 is, for example, a transmission input shaft of the transmission 18, via which the torque provided by the drive unit 14 can be introduced into the transmission. Overall, it can be seen that a torque can be transmitted between the output shaft 16 and the further shaft 32 via the friction clutch 10.

The powertrain 12 also includes an electronic computing device 34, also referred to as a controller. The friction clutch 10 can be operated by means of an electronic computing device 34. For this purpose, the electronic computer 34 actuates the friction clutch 10, in particular at least one actuator of the friction clutch 10, which is not shown in the figures, whereby, for example, the friction clutch 10 or an actuator, also referred to as an actuating element, is actuated by means of the electronic computer 34 and is controlled or preferably regulated in the process. In order to actuate, i.e., control or regulate, the friction clutch 10, in particular the actuating element, the electronic computing device 34 provides, for example, at least one, in particular, electrical signal, which is also referred to as an actuation signal. The control signal is transmitted, for example, from the electronic computing device 34 to the friction clutch 10, in particular to the actuating element, and is received by the friction clutch 10, in particular by the actuating element. The electronic computing device 34 has, for example, in particular a controller 36, by means of which the friction clutch 10, in particular the actuating element, is controlled, i.e., operated in a controllable manner.

In particular, in the case of an actuation or operation of the friction clutch 10, it is provided that the clutch torque of the friction clutch 10 is set by means of the electronic computer 34. The clutch torque is, for example, a torque which can be transmitted via or via the friction clutch 10, in particular from the output shaft 16 to the further shaft 32, and vice versa. The time is plotted on the respective abscissa 38 of the respective diagram, wherein, for example, the gear position of the transmission 18, in particular the set gear position, is plotted on the ordinate 40. Thus, curve 42 illustrates a shift of transmission 18. In the case of such a gear change, a gear change takes place, in which, for example, one gear of the transmission 18 is disengaged and another gear is engaged. In the exemplary embodiment illustrated in the figures, for example, in the case of a gear change, a gear change from fifth to sixth gear takes place, so that the previously mentioned gear change is an upshift. However, the foregoing and following discussion can be readily transferred to downshifts and vice versa.

The rotational speed is plotted on the ordinate 44, wherein the curve 46 illustrates the rotational speed of the output shaft 16 and thus of the input side 24 or the structural element 28. Curve 48 illustrates the rotational speed of the further shaft 32 and thus of the output shaft 26 or the structural element 30. The torque is plotted on the ordinate 50, wherein the curve 52 illustrates the clutch torque mentioned. Further, curve 54 illustrates the motor torque provided by the power plant 14 via the output shaft 16. Here, the drawing illustrates a traction situation or traction operation of the power plant 14. In traction mode, the drive unit 14 provides torque via the output shaft 16, so that in traction mode the further shaft 32 is driven by the output shaft 16 via the friction clutch 10. The foregoing and following explanations are equally applicable to the coasting or inertial conditions of the power plant 14. In overrun mode, for example, the output shaft 16 is driven by the further shaft 32 via the friction clutch 10.

For the method, provision is made for: by means of an electronic computer, in particular by actuating an actuating element, at least one slight slip of the friction clutch 10 is set in a targeted manner, as a result of which the friction clutch is operated in a targeted manner during the operating phases 56, 58 and 60 with the correspondingly set slight slip. Microslip is understood to mean a slight slip, so that the input side 24 and the output side 26 or the output shaft 16 and the further shaft 32 rotate at different rotational speeds from one another as a result of the microslip being set. In traction operation, the output shaft 16 has, for example, a first rotational speed, while the other shaft 32 has a second rotational speed which is lower than the first rotational speed. However, in coasting operation, the first rotational speed is less than the second rotational speed. The rotational speed difference between the rotational speeds of the output shaft 16 and the further shaft 32 is preferably at most 100 rpm, in particular at most 50 rpm, and preferably at most 20 rpm, wherein the rotational speed difference is greater than 0, and preferably at most 5 rpm. In other words, microslip is for example in the range of from 5 to 100, especially from 5 to 50, and preferably from 5 to 20 revolutions per minute. The operating phases 56 and 58 are, for example, a first operating phase.

Preferably, the microslip during the respective operating phase 56, 58, 60 is regulated by means of the regulator 36, i.e. set and maintained in a regulated manner, in particular regulated to a setpoint value. It is conceivable here for the respective microslidings set during the operating phases 56, 58 and 60 to be identical or different from one another. Thus, during the respective operating phase 56, 58, 60, for example, a microslip adjustment is carried out by means of the electronic computing device 34, in particular by way of the actuating element being actuated by the controller.

In order to achieve a particularly efficient and therefore effective operation of the drive train 12, it is also provided in the method that at least one overpressure of the friction clutch 10 is set in a targeted manner by means of the electronic computing device 34, in particular by actuating the actuating element, as a result of which the friction clutch 10 is operated in a targeted slip-free manner during operating phases 62, 64, which differ from the operating phases 56, 58 and 60, the operating phases 62, 64 also being referred to as second operating phases. The slip-free operation of the friction clutch 10 is understood to mean that the high clutch torque of the friction clutch 10 is set such that there is no slip between the input side 24 and the output side 26. Thus, no slip between the input side 24 and the output side 26 occurs, so that the output shaft 16 and the further shaft 32 rotate at the same rotational speed, due to or during non-slip operation. The operating phases 56, 58 and 60 are therefore operating phases during which the friction clutch 10 is operated with little slip. The operating phases 62, 64 are furthermore operating phases during which the friction clutch 10 is operated with an overpressure.

The operating phase 60 is, for example, a third operating phase which is immediately adjacent in time to the second operating phase 64. In this case, as shown in fig. 1, the previously described shifting of the transmission 18 and illustrated by the curve 42 is carried out in a third operating phase 60. Since the friction clutch 10 is operated with little slip during the third operating phase 60, the shifting operation can be carried out particularly comfortably, so that a particularly high level of driving comfort can be ensured for a passenger seated in the interior of the motor vehicle.

In particular, it is provided here that the respective first operating phase 56 or 58 is executed as a test phase. During or in the respective examination phase, at least one adjustment parameter for adjusting the respective microslip is determined, so that the regulator 36 can use the determined adjustment parameter for adjusting the microslip, i.e. set and hold the adjustment. It is therefore preferably provided that, during the third operating phase 60, the control parameters determined in at least one of the test phases, i.e. in the operating phase 62 and/or the operating phase 64, are used to control the creep by the controller 36. In other words, the controller 36 uses the control parameters previously determined in the respective test phase during the third operating phase 60 for controlling the microslip during the third operating phase 60 as a function of the previously determined control parameters. As a result, the friction clutch 10 can be operated with an overpressure in the operating phases 62, 64 and can therefore be operated efficiently. In addition, the shifting can be carried out particularly comfortably in the case of the third operating phase 60. The method is carried out in particular during a constant driving phase, in particular in a fixed gear. In the following, the method is explained again with the aid of the constant driving phase in the fixed gear, taking into account the checking phase and the phase of the overpressure. The background here is that, in order to keep the friction power particularly low, an overpressure of the friction clutch 10 is set in a phase other than shifting and in other special states, i.e. during driving in constant gear. As a result, the clutch is no longer operated in a slipping manner, so that losses due to the slipping occurring and the transmitted clutch torque can be at least largely eliminated.

In general, during driving in constant gear, i.e. in addition to gear changes or special states, such as idling or coasting, it is provided that a defined slip in the form of a slight slip of the friction clutch 10 is always set, wherein the slip can be changed as a function of the driving situation. This aspect is used for decoupling between the drive unit 14 and the transmission 18 in order to achieve a favorable Noise situation, which is also referred to as NVH performance (NVH-Noise Vibration Harshness). On the other hand, this serves to set the actual motor torque at the clutch, and so that the clutch does not operate with an overpressure, which is the basis for determining shifting comfort when a clutch change is carried out during a shift.

For setting the slip or microslip, for example, a pre-controlled PI controller can be used. This means that the motor torque supplied or transmitted by the drive unit 14 is controlled beforehand into the clutch torque taking into account the inertia torque, and the downstream PI controller adjusts for inaccuracies between the motor torque present and the set clutch torque. This inaccuracy occurs on the motor side, for example, as a result of the influence of load variations, which cannot be represented in the present motor torque or can be represented in the present motor torque only with a corresponding degree of accuracy, and on the other hand, on the transmission side, at the clutch, for example, as a result of the influence of the friction coefficient, which likewise cannot be represented in the model with the required degree of accuracy. If there is no inaccuracy on the motor side and on the transmission side between the represented and the actual motor torque, the regulator can be dispensed with and a purely pilot-controlled operation is sufficient.

since it is now provided that the clutch is operated in an overpressure, i.e. without slip, during the phase of driving in constant gear, i.e. for example during the operating phases 62 and 64, a check phase is carried out to determine at least one manipulated variable or a plurality of manipulated variables, the respective manipulated variable also being referred to as a manipulated variable component. In this case, the overpressure is suddenly withdrawn or terminated, for example, by means of the ramp 66 or in a ramped manner or in a parabolic or parabolic manner, and the desired theoretical slip is then set as a microslip. If the microslip is set constant, the regulator component present at this time is stored, for example, in a memory device of the electronic computing device 34 and is again converted into an overpressure. This procedure can be repeated as many times as necessary if, for example, the rotational speed of the drive 14 or output shaft 16 and/or the applied motor torque has changed by a certain value since the last test phase, in particular if changing boundary conditions are to be expected and further regulator components are to be requested, and/or if a control over the phase is based purely in time or if a transition to the next test phase is to be made after a certain maximum time of the overpressure.

Conventional systems without overpressure aim in particular to achieve the required shift quality by a correct setting of the creep and, associated therewith, a correct clutch torque. If too high a clutch torque is set, stress/overtightening occurs during torque overlap during, for example, an upshift. Conversely, if too low a clutch torque is set, motor stall occurs during or outside of the shift.

If the vehicle is driven only with an overpressure, i.e. without a test phase, there is the risk that the clutch torque is initialized to the incorrect torque when the gear shift is initiated and the overpressure is removed. In general, when the overpressure is removed, the motor torque is additionally adjusted by means of a correction value, also referred to as an offset value, which is calculated, for example, from the moment of inertia/rotational inertia and the rotational speed gradient of the drive unit 14. In addition, the initialization torque can also be provided with an additional correction value (offset).

The advantage of the method used in the overpressure phase and the creep phase is, in particular, that by combining the overpressure phase and the implemented test phase, an increase in efficiency and an always good shift quality can be achieved. Thus, this method can combine the main advantages of the friction clutch 10 operating with overpressure with the advantages of the friction clutch 10 operating with a slight slip, so that a comfortable and efficient operation can be achieved.