DE102021123838A1 - Method for adjusting a slip on a friction clutch, control unit, computer program product and hybrid module - Google Patents

Abstract

The invention relates to a method for adjusting slip on a friction clutch (1) in a drive train (3) of a motor vehicle (4) that can be operated with an electric machine (2), comprising at least one an electric machine (2) that can be coupled and drives the motor vehicle (4), a clutch actuator (5) that actuates the friction clutch (1), and a control unit (14) that is connected and set up with the electric machine (2) and the clutch actuator (5). to operate the drive train (3) of the motor vehicle (4) by means of a slip controller (6), the slip controller (6) having a P controller (7) and an I controller (8), which are each set to a slip difference (9 ) formed from the difference between the setpoint slip (10) and the actual slip (11), the output (12) of the P controller (7) acting on the electrical machine (2) to control it and the output ( 13) of the I controller (8) e.g acts on the clutch actuator (5) to control it.

Description

The present invention relates to a method for adjusting slippage on a friction clutch in a drive train of a motor vehicle that can be operated with an electric machine, comprising at least one electric machine that can be coupled to the drive train via the friction clutch and drives the motor vehicle, a clutch actuator that actuates the friction clutch, and a control unit, which is connected to the electric machine and the clutch actuator and is set up to operate the drive train of the motor vehicle by means of a slip controller, the slip controller having a P controller and an I controller, each of which is formed with a slip difference from the difference between the setpoint slip and actual slip is applied. The invention also relates to a control unit, a computer program product and a hybrid module.

Electric motors are increasingly being used to drive motor vehicles in order to create alternatives to internal combustion engines that require fossil fuels. Significant efforts have already been made to improve the suitability for everyday use of electric drives and also to be able to offer users the driving comfort they are accustomed to.

A detailed description of an electric drive can be found in an article in the ATZ magazine, volume 113, 05/2011, pages 360-365 by Erik Schneider, Frank Fickl, Bernd Cebulski and Jens Liebold with the title: Highly integrative and flexible electric drive unit for electric Vehicles. This article describes a drive unit for an axle of a vehicle, which includes an electric motor that is arranged concentrically and coaxially with a bevel gear differential, with a switchable 2-speed planetary gear set being arranged in the power train between the electric motor and the bevel gear differential, which is also is positioned coaxially to the electric motor or the bevel gear differential or spur gear differential. The drive unit is very compact and allows a good compromise between climbing ability, acceleration and energy consumption due to the switchable 2-speed planetary gear set. Such drive units are also referred to as e-axles or electrically operable drive train.

In addition to purely electrically operated drive trains, hybrid drive trains are also known. Such drive trains of a hybrid vehicle usually include a combination of an internal combustion engine and an electric motor, and allow - for example in urban areas - a purely electric mode of operation with simultaneous sufficient range and availability, especially for cross-country trips. In addition, there is the possibility, in certain operating situations, to be driven simultaneously by the internal combustion engine and the electric motor.

Like for example from the EP 0 773 127 A1 , DE 100 18 926 A1 and U.S. 2007/0175726 A1 is known, in such hybrid drive concepts, a clutch arrangement can be arranged between the internal combustion engine and the electric motor in order to separate the internal combustion engine from the electric motor and the remaining drive train of the hybrid vehicle. When driving purely electrically, the first clutch arrangement is then opened and the internal combustion engine is switched off, so that the output torque of the hybrid vehicle is applied solely by the electric motor. For example, hydraulic clutch actuation systems—also referred to as hydraulic release systems—are known for actuating such clutch arrangements in hybrid vehicles.

Such a clutch arrangement can usually assume different states, such as open, slipping or sticking. The speeds of the input and output shafts of the clutch arrangement are different - except for this case. When starting the motor vehicle with an internal combustion engine, the clutch arrangement has to be brought from an open state, via a slipping state, into a sticking state. Automated clutches often also use slip control to achieve better isolation from vibrations in the drive train.

The slip control is achieved by tracking the clutch assembly. Here, the transmitted torque can be dynamically increased or reduced in order to influence the speed difference of the output shaft in relation to the input shaft of the clutch arrangement. In the case of slip control, an attempt is made to achieve a defined slip in the speeds, which means that an attempt is made to set a specified speed difference between the input shaft and the output shaft of the clutch arrangement.
The drive unit with the electric machine adjusts the torque desired by the driver as precisely as possible. The slip control algorithm superimposes a torque difference on this driver's desired torque through targeted clutch actuator movements in order to adjust the slip as desired. The slip control algorithm uses a proportional control component and an integration control component to set the desired torque difference. Proportional control components are often changing quickly, whereas the integration control component is changed in a more slowly tracking manner. To set the desired slip on the Clutch arrangement, a torque difference is superimposed on the target torque by driving the clutch actuator as quickly as possible. Due to the structural design, however, a clutch actuator can usually only follow this torque difference up to a specific rate of change of the setpoint signal; this is also referred to as a low-pass behavior of the corresponding actuator system. Smaller frequencies can be set well, whereas higher frequencies can no longer be set because the actuator is too slow/sluggish for this.

It is therefore the object of the present invention to provide a method for adjusting slippage on a friction clutch in a drive train of a motor vehicle that can be operated with an electric machine, which method is improved in terms of its control dynamics.

This object is achieved by a method for adjusting slippage on a friction clutch in a drive train of a motor vehicle that can be operated with an electric machine, comprising at least one electric machine that can be coupled to the drive train via the friction clutch and drives the motor vehicle, a clutch actuator that actuates the friction clutch, and a control unit , which is connected to the electrical machine and the clutch actuator and set up to operate the drive train of the motor vehicle by means of a slip control system, the slip control system having a P controller and an I controller, each of which is formed with a slip difference from the difference between the setpoint Slip and actual slip is applied, with the output of the P controller for controlling the electrical machine acting on this and the output of the I controller for controlling the clutch actuator acting on it.

This achieves the advantage that the slip control has a significantly improved dynamic control behavior. The required torque difference for setting the target slip is provided by a combination of clutch actuator and electric machine. The torque difference due to the fast-acting proportional control component is provided by the electrical machine, while the torque difference is provided by the clutch actuator due to the rather sluggish integration component of the slip controller. The integral part of the slip control only acts on the clutch actuator and not on the electric machine. However, the P controller component of the slip control acts together with the driver's desired torque on the electric machine, which can implement the desired variables quickly and very precisely. The arrangement of the electrical machine in the drive train can be chosen freely, it only has to be ensured that the torque on the friction clutch can be influenced directly by the electrical machine.

A further significant advantage of the method according to the invention is that the clutch actuator has to withstand fewer load cycles, since the relocation into the electric machine takes over the high-frequency position changes, which in total mean a large amount of clutch travel added up. This can significantly increase the service life of the clutch actuator.

Furthermore, the process-related modulations on the electric machine in the vehicle are usually not noticeable, whereas the corresponding modulations on a clutch actuator or friction clutch in the vehicle are usually noticeable.

First, the individual elements of the claimed subject matter of the invention are explained below in the order in which they are mentioned in the set of claims, and particularly preferred configurations of the subject matter of the invention are described below.

The use of the method according to the invention in a hybrid or fully electrically operated drive train of a motor vehicle is particularly preferred.

For the purposes of this application, the drive train of a motor vehicle is understood to mean all components that generate the power for driving the motor vehicle in the motor vehicle and transmit it to the road via the vehicle wheels.

For the purposes of this application, motor vehicles are land vehicles that are moved by machine power without being tied to railroad tracks. A motor vehicle can be selected, for example, from the group of passenger cars (cars), trucks (lorries), mopeds, light motor vehicles, motorcycles, buses (COM) or tractors. A hybrid electric vehicle, also referred to as a hybrid electric vehicle (HEV), is an electric vehicle that is powered by at least one electric motor and another energy converter and draws energy from both its electrical storage (battery) and additional fuel that is carried.

A control unit, as used in the present invention, is used, in particular, for the electronic control and/or regulation of one or more technical systems of the motor vehicle. In particular, a control unit for Control and / or regulation of one or more friction clutches and / or electrical machines may be provided.

A control unit has in particular a wired or wireless signal input for receiving electrical signals, in particular, such as sensor signals. Furthermore, a control unit likewise preferably has a wired or wireless signal output for the transmission of, in particular, electrical signals, for example to electrical actuators or electrical consumers of the motor vehicle.

Control operations and/or regulation operations can be carried out within the control unit. It is particularly preferred that the control unit includes hardware that is designed to run software. The control unit preferably comprises at least one electronic processor for executing program sequences defined in software.

The control unit can also have one or more electronic memories in which the data contained in the signals transmitted to the control unit can be stored and read out again. Furthermore, the control unit can have one or more electronic memories in which data can be stored in a changeable and/or unchangeable manner.

A control unit can include a plurality of control devices, which are arranged in particular spatially separated from one another in the motor vehicle. Control units are also referred to as electronic control units (ECU) or electronic control modules (ECM) and preferably have electronic microcontrollers for carrying out computing operations for processing data, particularly preferably using software. The control devices can preferably be networked with one another, so that a wired and/or wireless data exchange between control devices is made possible. In particular, it is also possible to network the control units with one another via bus systems present in the motor vehicle, such as a CAN bus or LIN bus.

One use of the method according to the invention is very particularly preferably provided in a hybrid module. In a hybrid module, structural and functional elements of a hybridized drive train can be spatially and/or structurally combined and preconfigured, so that a hybrid module can be integrated in a particularly simple manner into a drive train of a motor vehicle. In particular, an electric motor and a clutch system, in particular with a separating clutch designed as a friction clutch for coupling the electric motor into and/or decoupling the electric motor from the drive train, can be present in a hybrid module.

• P0: der Elektromotor ist vor der Brennkraftmaschine angeordnet und beispielsweise über einen Riemen mit der Brennkraftmaschine gekoppelt. Bei dieser Anordnung des Elektromotors wird dieser auch gelegentlich als Riemenstartergenerator (RSG) bezeichnet,
• P1: der Elektromotor ist direkt hinter der Brennkraftmaschine angeordnet. Die Anordnung des Elektromotors kann beispielsweise kurbelwellenfest vor der Anfahrkupplung erfolgen,
• P2: der Elektromotor ist zwischen einer häufig als K0 bezeichneten Trennkupplung und der Anfahrkupplung aber vor dem Fahrzeuggetriebe im Antriebsstrang angeordnet,
• P3: der Elektromotor ist im Fahrzeuggetriebe und/oder der Getriebeausgangswelle angeordnet,
• P4: der Elektromotor ist an einer bestehenden oder separaten Fahrzeugachse angeordnet und
• P5: der Elektromotor ist am oder im Fahrzeugrad angeordnet, beispielsweise als Radnabenmotor.

A hybrid module can be divided into the following categories P0-P4 depending on the point of intervention of the electric motor in the drive train:

• P0: the electric motor is arranged in front of the internal combustion engine and is coupled to the internal combustion engine via a belt, for example. With this arrangement of the electric motor, it is also sometimes referred to as a belt starter generator (RSG),
• P1: the electric motor is located directly behind the internal combustion engine. The electric motor can be arranged, for example, on the crankshaft in front of the starting clutch,
• P2: the electric motor is located between a separating clutch, often referred to as K0, and the starting clutch, but in front of the vehicle transmission in the drive train,
• P3: the electric motor is arranged in the vehicle transmission and/or the transmission output shaft,
• P4: the electric motor is arranged on an existing or separate vehicle axle and
• P5: the electric motor is arranged on or in the vehicle wheel, for example as a wheel hub motor.

According to a further preferred embodiment of the subject matter of the invention, it can be provided that the hybrid module is configured as a P1 or P2 hybrid module.

According to an advantageous embodiment of the invention, it can be provided that the output of the P controller acts on the clutch actuator and the electrical machine.

According to a further preferred development of the invention, it can also be provided that the output of the P controller acts on the clutch actuator and the electric machine via a factor f, which is selected between 0<=f<=1. In this way, it can be achieved that the slip control structure can be adjusted further in an optimized manner by a suitable choice of the factor f.

Furthermore, according to a likewise advantageous embodiment of the invention, it can be provided that the output of the P controller acts on the electric machine via a factor k _EM and/or acts on the clutch actuator via a factor k _KU . The effect chains of a speed error are clearly different if the Speed error affects the electric machine or the clutch actuator. Any necessary physical adjustments to these effect chains can be mapped by selecting a suitable parameter.

According to a further particularly preferred embodiment of the invention, provision can be made for the P controller to be in the form of a PD controller. In this way, the effect can be achieved in particular that the phase reserve of the control can be increased via the PD controller and the PD controller thus has a stabilizing effect on the control loop.

The object of the invention is further achieved by a computer program product that is stored on a machine-readable carrier, or computer data signal, embodied by an electromagnetic wave, with computer program code that is suitable for carrying out the method according to one of claims 1 to 5.

The object of the invention can also be achieved by a control unit for setting a slip on a friction clutch in a drive train of a motor vehicle that can be operated with an electric machine, wherein the control unit can be coupled to the electric machine and the clutch actuator and is set up to control the drive train of the motor vehicle by means of a To operate slip control, wherein the control unit comprises a processor and a memory containing a computer program code, wherein the memory and the computer program code are configured with the processor to cause the control unit to perform a method according to any one of claims 1 to 5.

Finally, the object of the invention is also achieved by a hybrid module for a drive train of a motor vehicle comprising an electric machine and a clutch system, in particular with a friction clutch for coupling the electric machine into and/or decoupling the electric machine from the drive train, further comprising a control unit claim 7.

The invention will be explained in more detail below with reference to figures without restricting the general inventive idea.

• 1a ein in einem Antriebsstrang eines Kraftfahrzeugs angeordnetes Hybridmodul in einer schematischen Blockschaltdarstellung,
• 1b ein in vollelektrisch betreibbarer Achsantriebsstrang eines Kraftfahrzeugs in einer schematischen Blockschaltdarstellung,
• 2 Darstellung einer ersten Ausführungsform einer Regelungsstrecke in einer Blockschaltansicht,
• 3 Darstellung einer zweiten Ausführungsform einer Regelungsstrecke in einer Blockschaltansicht.

It shows:

• 1a a hybrid module arranged in a drive train of a motor vehicle in a schematic block diagram,
• 1b a fully electrically operable axle drive train of a motor vehicle in a schematic block diagram,
• 2 Representation of a first embodiment of a controlled system in a block diagram,
• 3 Representation of a second embodiment of a controlled system in a block diagram.

The 1a 1 shows a friction clutch 1 in a drive train 3 of a motor vehicle 4 that can be operated with an electric machine 2. The friction clutch 1 is part of a hybrid module 17, which is arranged in the drive train 3 of the motor vehicle 4. The hybrid module 17 designed as a P2 hybrid module comprises an electric machine 2 and a clutch system 18 with two friction clutches 1 for coupling the electric machine 2 into and/or decoupling the electric machine 2 from the drive train 3. The hybrid module 17 also has a control unit 14.

The 1 b shows a friction clutch 1 in a drive train 3 of a motor vehicle 4 that can be operated with an electric machine 2. The friction clutch 1 is arranged as part of a clutch system 18 in the direction of torque flow between the electric machine 2 and a vehicle wheel, so that the friction clutch 1 enables the electric Machine 2 in and / or decoupling the electric machine 2 from the drive train 3 can be realized. The drive train 3 shown also has a control unit 14.

The control unit 14, as for example in the embodiments of a drive train 3 1a or 1b Can find application is set up, inter alia, for setting a slip on the friction clutch 1, wherein the control unit 14 is coupled to the electric machine 2 and the clutch actuator 5, which is indicated by the dashed lines in FIG 1 is indicated. The drive train 3 of the motor vehicle 4 can be operated with a slip control system 6 by means of the control unit 14 . For this purpose, the control unit 14 has a processor 15 and a memory 16 containing a computer program code, the memory 16 and the computer program code being configured with the processor 15 to cause the control unit 14 to carry out a slip control 6 .

The corresponding procedure for this is explained in more detail below. For this shows 2 a first possible controlled system.

One can see the electric machine 2, which can be coupled via the friction clutch 1 and drives the motor vehicle 4, as well as a clutch actuator 5 that actuates the friction clutch 1. The control unit 14, which is connected to the electric machine 2 and the clutch actuator 5 and set up, is indicated by the dashed lines. to operate the drive train 3 of the motor vehicle 4 by means of a slip control system 6 .

The slip control 6 has a P-controller 7 and an I-controller 8, to which a slip difference 9 formed from the difference between the target slip 10 and the actual slip 11 is acted upon. The output 12 of the P controller 7 for controlling the electric machine 2 acts on it, while the output 13 of the I controller 8 for controlling the clutch actuator 5 acts on it. From the 2 It can also be seen that the output 12 of the P controller 7 acts not only on the electric machine 2 but also on the clutch actuator 5 . In this case, the output 12 of the P controller 7 is connected to the clutch actuator 5 and the electric machine 2 via a factor f, which is selected between 0<=f<=1. Any slip control structure can be set by a suitable choice of the factor f. This can be advantageous for parameterization and for comparisons.

Like in the 3 shown, the output 12 of the P controller 7 can also act on the electric machine 2 via a factor k _EM and/on the clutch actuator 5 via a factor k _KU . The P controller 7 in the exemplary embodiments shown 2-3 is designed as a PD controller.

The driver's desired torque selected by a driver of the vehicle can in particular also be applied to the friction clutch 1 or the clutch actuator 5 . This is in the 2-3 indicated by an unspecified arrow.

The invention is not limited to the embodiments shown in the figures. The foregoing description is therefore not to be considered as limiting but as illustrative. The following patent claims are to be understood in such a way that a mentioned feature is present in at least one embodiment of the invention. This does not exclude the presence of other features. If the patent claims and the above description define 'first' and 'second' feature, this designation serves to distinguish between two similar features without establishing a ranking.

Reference List

1

friction clutch

2

electric machine

3

powertrain

4

motor vehicle

5

clutch actuator

6

slip control

7

P controller

8th

I controller

9

slip difference

10

target slip

11

actual slip

12

Exit

13

Exit

14

control unit

15

processor

16

Storage

17

hybrid module

18

clutch system

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was 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.

Patent Literature Cited

• EP 0773127 A1 [0005]
• DE 10018926 A1 [0005]
• US20070175726A1 [0005]

Claims (9)

Method for setting a slip on a friction clutch (1) in a drive train (3) of a motor vehicle (4) that can be operated with an electric machine (2), comprising at least one that can be coupled to the drive train (3) via the friction clutch (1) and the motor vehicle (4) driving electrical machine (2), a clutch actuator (5) that actuates the friction clutch (1) and a control unit (14) which is connected to the electrical machine (2) and the clutch actuator (5) and is set up to control the drive train ( 3) of the motor vehicle (4) by means of a slip control (6), wherein the slip control (6) has a P controller (7) and an I controller (8), each with a slip difference (9) formed from the Difference between target slip (10) and actual slip (11) is applied, characterized in that the output (12) of the P controller (7) acts on the electrical machine (2) to control it and the output (13 ) of the I controller (8) to Control of the clutch actuator (5) acts on this. procedure after claim 1 , characterized in that the output (12) of the P controller (7) acts on the clutch actuator (5) and the electrical machine (2). procedure after claim 2 , characterized in that the output (12) of the P controller (7) acts on the clutch actuator (5) and the electrical machine (2) via a factor f, which is selected between 0<=f<=1. procedure after claim 1 or 2 , characterized in that the output (12) of the P controller (7) acts on the electric machine (2) via a factor k _EM and/or acts on the clutch actuator (5) via a factor k _KU . Method according to one of the preceding claims, characterized in that the P controller (7) is designed as a P(D) controller. Computer program product stored on a machine-readable medium, or computer data signal embodied by an electromagnetic wave, with computer program code suitable for carrying out the method according to one of Claims 1 until 5 . Control unit (14) for setting a slip on a friction clutch (1) in a drive train (3) of a motor vehicle (4) that can be operated with an electric machine (2), the control unit (14) being connected to the electric machine (2) and the clutch actuator (5) can be coupled and is set up to operate the drive train (3) of the motor vehicle (4) by means of a slip control (6), the control unit (14) comprising a processor (15) and a memory (16) which contains a computer program code , wherein the memory (16) and the computer program code are configured with the processor (15), the control unit (14) for performing a method according to any one of Claims 1 until 5 to cause. Hybrid module (17) for a drive train (3) of a motor vehicle (4) comprising an electric machine (2) and a clutch system (18), in particular with a friction clutch (1) for engaging the electric machine (2) in and/or disengaging the Electrical machine (2) from the drive train (3), further comprising a control unit (14). claim 7 . Hybrid module (17) after claim 8 , characterized in that the hybrid module (17) is configured as a P1 or P2 hybrid module.

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