DE102012019036A1 - Method for controlling electro-mechanical clutch system in motor vehicle, involves controlling engine torque by setpoint torque, and actuator to lowest possible difference between target and engine torques independent of clutch travel - Google Patents

Abstract

The method involves opening and closing a clutch (2) of a motor vehicle through an actuator (9), and mechanically decoupling the actuator from a clutch pedal (12). A starting state or a starting operation of the motor vehicle is detected, and a target torque is calculated. An engine torque (Mmot) is controlled by a setpoint torque, and the actuator is simultaneously controlled to a lowest possible difference between the target torque and the engine torque, which is independent of a clutch travel (w) of the clutch pedal. Independent claims are included for the following: (1) a motor vehicle; (2) a computer program for controlling an electro-mechanical clutch system in a motor vehicle; and (3) a computer program product for controlling an electro-mechanical clutch system in a motor vehicle.

Description

The invention relates to a method for controlling an electromechanical clutch system in a motor vehicle, wherein the motor vehicle has a clutch which can be opened and closed via an actuator, wherein the actuator is mechanically decoupled from a clutch pedal.

In an electromechanical clutch system (clutch by wire) there is no direct mechanical connection between the clutch pedal and the clutch. Rather, a clutch pedal position is electronically delivered to a control system which acts on the clutch via an actuator. The actual actuation of the clutch is thus ultimately a force that is generated in the actuator and not on the clutch pedal. The actuator may have, for example, electromotive, hydraulic or pneumatic components.

An object of the invention is based can be seen to provide a clutch-friendly and the driver assisting method for controlling a clutch.

This object is achieved with the features of claim 1. Further embodiments are the subject of the dependent claims, which can be combined in a technologically meaningful way. The description, in particular in connection with the figures, additionally characterizes and specifies the invention.

• – Erfassen eines Anfahrzustands bzw. Anfahrvorgangs des Kraftfahrzeugs,
• – Berechnen eines Solldrehmoments,
• – Regeln des Motordrehmoments auf das Solldrehmoment, und gleichzeitig Regeln des Aktors auf eine möglichst geringe Differenz zwischen dem Solldrehmoment und dem Motordrehmoment, unabhängig von einem Kupplungsweg an dem Kupplungspedal.

Accordingly, a method is provided for controlling an electromechanical clutch system in a motor vehicle, the motor vehicle having a clutch which can be opened and closed via an actuator, wherein the actuator is mechanically decoupled from a clutch pedal, with the steps:

• Detecting a starting state or startup process of the motor vehicle,
• Calculating a setpoint torque,
• - Regulation of the engine torque to the target torque, and at the same time controlling the actuator to a minimum difference between the target torque and the engine torque, regardless of a clutch travel on the clutch pedal.

Thus, the clutch can be controlled via the actuator independently of the clutch pedal travel, and at the same time, the engine torque can be adjusted to a given condition. As a result, the driver is supported when starting and the engine only outputs the engine torque, which is actually required for starting. This can avoid that when engaging a greater torque is introduced into the clutch, as is required for starting (for example, at relatively high engine speed and when the vehicle is stationary). As a result, the clutch is protected, so that maintenance and repair costs can be reduced to a minimum. Conversely, by controlling the engine torque at the same time, the engine can be used up to its power limit in order to drive quickly and comfortably under different conditions.

The starting state prevails when the vehicle is stationary or moving at a speed which is relatively low, in particular less than or equal to a walking speed, and the driver releases the clutch pedal when a gear is engaged. The start-up state can be signal-technically detected by the driver releasing the clutch pedal, that is, wanting to engage it.

In one embodiment, a slope on which the vehicle is located, is determined, wherein the target torque is increased at a positive slope.

As a result, the driver does not need to take into account a slope when starting, for example, by giving more gas, so changing the accelerator pedal position. The slope is automatically detected and the desired torque increased, so that an increased engine torque is delivered and the vehicle is set in motion with the usual acceleration for the respective accelerator pedal position.

In one embodiment, an additional load of the vehicle is detected, wherein in the presence of an additional load, the target torque is increased.

The loading can be determined for example by signals on an electronic damper control, a headlight range control or a level control. Furthermore, it can be concluded from a previous start-up, which has required a higher torque due to a load on the load. In a loaded vehicle, it may be necessary to give more gas when starting. By taking account of the load, the driver can be assisted by automatically increasing the setpoint torque and, as in taking into account the gradient, to set the vehicle in motion with the acceleration that is usual for the respective accelerator pedal position.

According to a further embodiment, the driver setpoint torque defined by an accelerator pedal position is determined and a coefficient of friction Correction value (mü) determined, which corresponds to the proportion of the transferable to the roadway driver target torque, wherein in the event that the proportion is less than 100%, the target torque (Msoll) is reduced, in particular proportionally reduced. As a result, for example, due to environmental parameters caused reduction of the coefficient of friction between the road and tire bill and prevents it from spinning around the wheels.

The coefficient of friction correction value is a measure of a coefficient of friction that prevails between the driven wheels and the roadway. This changes constantly in the operation of the vehicle depending on the environment and the road surface. Some environmental parameters are easily measurable, so that the friction coefficient can be estimated within certain limits or can be specified based on empirically determined data. With an increased coefficient of friction, an increased torque can also be output to the driven wheels.

If the driver setpoint torque defined by the accelerator pedal position can be transmitted completely to the roadway, then it is possible, for example, to assign the standardized value 1 to the friction coefficient correction value. If this is not the case and thus the proportion of the driver-target torque transferable to the roadway is <100%, which may be the case especially in worse environmental conditions such as wet roads or in the case of black ice, the friction coefficient correction value is assigned a smaller value between 0 and 1 too. In order to calculate this smaller value, it is possible to use the ratio of still transmittable torque and driver setpoint torque according to a further method variant. The setpoint torque reduced in the above sense can then result multiplicatively as the product of the setpoint torque and a coefficient of friction correction value <1. Of course, there are other ways to calculate such a reduced target torque using a Reibwert-correction value.

According to a further embodiment, the friction coefficient correction value is reduced in the presence of a rain sensor signal proportional to the rain intensity.

On wet roads, a lower torque can be transmitted to the wheels. Accordingly, the friction value correction value can be reduced in the rain. The rain sensor may be provided, for example, on a windshield to automatically activate a windshield wiper system when it rains.

In a further refinement, an ambient temperature is detected, wherein the friction coefficient correction value is increased when the ambient temperature is elevated.

Usually, tires have a better coefficient of friction at elevated temperature. Accordingly, the coefficient of friction correction value can also be increased at elevated ambient temperatures.

According to a further embodiment, a signal corresponding to the loading is detected, wherein the friction value correction value is increased at an increased loading.

When loaded, a load acting on the wheels increases. As a result, an increased torque can be transmitted to the driven wheel. Accordingly, with increased loading, the coefficient of friction correction value can be increased. The loading can be determined in the manner described above. The loading can therefore be considered several times in the scheme, namely once due to an increased demand for torque and once to determine the friction coefficient correction value.

In a further refinement, in particular after at least one starting process, a traction signal is detected by a traction control control unit, and the friction coefficient correction value is reduced when the wheel slips. In this case, according to a further embodiment, the reduction can be inversely proportional to the strength of the traction signal, it being assumed that the traction signal is zero if there is no wheel slip. With one traction signal per driven wheel, for the purposes of reducing the coefficient of friction correction, one can use either the average traction signal strength or the traction signal associated with the greatest wheel slip.

The traction control regulates the slip on the wheels. This can be done by engaging in a brake system or by engaging in an engine controlling electronics. If there is a condition in which the road surface is slippery, the traction control works to prevent the driven wheels from spinning. Accordingly, after a wheel has been slowed down by the traction control, it is certain, at least for a short period of time, that the vehicle is on a slippery surface. Accordingly, the friction coefficient correction value can be reduced.

In a further refinement, the control in a sprint mode regulates a wheel slip prevailing on a driven wheel to a setpoint slip.

The sprint mode can be activated via a button or activated automatically when There are certain parameters that allow the conclusion that the driver wants to move the vehicle sportily and as quickly as possible, for example, when deactivating the traction control.

The wheel slip depends directly on the torque output. The wheel slip can be calculated as follows: Srad = (nR - nR0) / nR0

Here nR is the actual speed at which the wheel is currently rotating and nR0 is a speed that is calculated from the quotient of the vehicle speed and the wheel circumference.

The wheel slip is almost zero for a non-driven wheel. With a braking wheel, the wheel slip can be between -0.2 and 0.0. With a driven wheel, the slip is slightly greater than 0. The nominal slip can be selected so that the achievable with the vehicle propulsion for each speed, especially at low speeds when starting, as large as possible. In the sprint mode (race mode), this configuration allows just as much torque to be delivered to the driven wheel that it spins with a defined wheel slip, thereby generating a maximum achievable propulsion. Depending on the tires and the road, the wheel slip may be between 0.1 and 0.2.

The clutch system may be provided in a motor vehicle having a control unit, wherein the control unit has a storage means with a computer program stored thereon, wherein the computer program may be designed to carry out a method according to one of the claims.

The control unit may have a digital microprocessor unit (CPU) data-connected to a memory system and a bus system, a random access memory (RAM) and a memory means. The CPU is adapted to execute instructions executed as a program stored in a memory system, to detect input signals from the data bus, and to output signals to the data bus. The storage system may have various storage media such as optical, magnetic, solid state and other non-volatile media on which a corresponding computer program for carrying out the method and the advantageous embodiments is stored. The program may be such that it is capable of embodying the methods described herein so that the CPU may perform the steps and thereby control the clutch system.

Suitable for performing a method is a computer program having program code means for performing all the steps of any one of the claims when the program is run on a computer.

The computer program can be easily read into existing control units and used to control an electromechanical coupling system. Provided for this purpose is a computer program product with program code means, which are stored on a computer-readable data carrier in order to carry out the method according to any of the claims, when the program product is executed on a computer. The computer program product can also be integrated as a retrofit option in a control unit.

• – Mittel zum Erfassen eines Anfahrzustandes,
• – Mittel zum Berechnen eines Solldrehmoments,
• – Mittel zum Regeln des Motordrehmoments auf das Solldrehmoment, und zum gleichzeitigen Regeln des Aktors auf eine möglichst geringe Differenz zwischen dem Solldrehmoment und dem Motordrehmoment unabhängig von einem Kupplungsweg an dem Kupplungspedal.

Another aspect of the invention relates to an apparatus for controlling an electromechanical clutch system in a motor vehicle, the motor vehicle having a clutch which can be opened and closed via an actuator, wherein the actuator is mechanically decoupled from a clutch pedal, the apparatus comprising:

• Means for detecting a start-up condition,
• Means for calculating a setpoint torque,
• - Means for regulating the engine torque to the target torque, and for simultaneously controlling the actuator to a minimum difference between the target torque and the engine torque regardless of a clutch travel on the clutch pedal.

In one embodiment of the apparatus, means are provided which determine a slope on which the vehicle is located, the setpoint torque being increased on a positive gradient.

In a further embodiment of the apparatus, means are provided which detect an additional load of the vehicle, with additional loading, the target torque is increased.

In a further embodiment of the apparatus, means are provided for determining a driver setpoint torque defined by an accelerator pedal position, and means for determining a coefficient of friction correction value which corresponds to the fraction of the driver-setpoint torque that can be transmitted to the lane, wherein the means for the case Proportion is less than 100%, reduce the target torque Msoll.

In a further embodiment of the apparatus, means are provided for reducing the setpoint torque Msetpoint by a factor which is the ratio of torque transferable to the lane to driver setpoint torque.

In a further embodiment of the apparatus further means are provided which reduce the friction coefficient correction value in the presence of a rain intensity signal proportional to the rain intensity.

In a further embodiment of the apparatus, means for detecting a signal corresponding to the loading are present, as well as means which increase the friction coefficient correction value at an increased loading.

In a further embodiment of the apparatus, means are present which detect the traction signal of a traction control controller and means which reduce the Reibwert-Korrekturwert mü when wheel slip, the reduction of Reibwert-correction value (mü) in particular inversely proportional to the strength of the traction signal.

In a further embodiment of the apparatus, means are provided which adjust a wheel slip prevailing on a driven wheel to a setpoint slip in a sprint mode.

Some embodiments of the invention will be described below with reference to the drawings. Show it:

1 FIG. 2 schematically shows a clutch system of a motor vehicle, and FIG

2 : schematically a procedure for controlling the coupling system.

In the figures, the same or equivalent components and elements are provided with the same reference numerals.

1 schematically shows a coupling system 1 with a clutch 2 , which is designed to frictionally lock a motor 3 with a gear 4 connect to. For this purpose, the coupling 2 friction linings 5 on, which in closed or connected coupling 2 about springs 6 be brought into frictional engagement with each other. To open the clutch 2 can the friction linings 5 or the springs 6 through a cylinder 7 be relieved. The cylinder 7 is in fluid communication with a piston 8th , which has an actor 9 can be moved linearly. Hereby, a fluid pressure can be built, which the cylinder 7 emotional. The actor 9 is from a control unit 10 controlled, which data transmitting with a displacement sensor 11 connected is. The displacement sensor 11 is on a clutch pedal 12 provided, wherein the displacement sensor 11 equipped to one on the clutch pedal 12 covered path w to capture. Depending on the position of the clutch pedal 12 can handle the clutch 2 without a direct mechanical connection between the clutch pedal 12 and the clutch 2 to be controlled. The clutch pedal 12 has a spring, not shown, which the clutch pedal 12 in his in 1 shown position (pedal travel w = 0) pushes back when the pedal is released.

The coupling system 1 can be provided in an otherwise not shown motor vehicle, in which an output of the transmission 4 about a differential 13 with wheels 14 torque transmitting connected, so that the engine 3 over the clutch 2 or the transmission 4 can drive the motor vehicle.

The motor 3 can be operated with a variable engine speed nMot and a variable engine torque Mmot. The driver can use an accelerator pedal 16 specify a driver setpoint torque MF. The gas pedal 16 is for this purpose data transmitting with the control unit 10 connected. The control unit 10 can be designed to that of the engine 3 output engine torque Mmot also independent of the position of the accelerator pedal 16 to control.

It is related to the description of in 2 illustrated diagram on the in 1 shown components and their reference numerals with reference. 2 shows a schematic diagram of a process flow, which in the control unit 10 can be implemented. At the control unit 10 it may be the electronic engine control unit which, as is well known, has a CPU and a RAM. A control panel 17 represents a control or command for changing or maintaining the position x of the actuator 9 , A control panel 18 represents a control or command with that of the engine 3 output motor torque Mmot is controlled.

It is intended, in a normal mode, a first controller 19 provide in normal mode via the control panel 17 the actor 9 regulates. From an accelerator pedal position v, a pitch a, a payload mzu and a coefficient of friction correction mü, a setpoint torque MSoll is calculated. At a summing point 20 it will be from the engine 3 just output engine torque Mmot deducted from the target torque MSoll. The first controller 19 thus regulates the difference between the setpoint torque MSoll and the currently applied motor torque Mmot. The controller is designed as a PID controller. Thus, the controller has a constant proportional component P, a time-integrating component I and a time-differentiating component D.

In the controller 19 can thus implement a proportional share, a time-integrated share and a temporally differentiating share become. The regulator 19 can therefore be adjusted so that a temporal behavior of the actor 9 and the clutch 2 by the actor 9 is actuated.

In the coefficient of friction correction mü (operator 15 ), among other things, the gas pedal position v for determining the driver target torque ("desired torque"), the payload mzu flow (step 27 ) and the ambient temperature Tumg (step 28 ) one. In addition, it is considered whether it is raining (step 29 ). This can be detected for example via a rain sensor, not shown in the figures. Furthermore, in step 30 a signal of a traction control taken into account by the coefficient of friction correction mü is reduced in regulating, ie a spinning wheel targeted braked traction control. When it rains, the coefficient of friction correction mü is also reduced.

The gas pedal position v can via an accelerator pedal map 21 be converted to obtain a non-linear relationship between the driver target torque MF and the accelerator pedal position v. For example, in a sporty design, the ratio between the accelerator pedal travel v may be very small or progressive, thus the engine 3 reacts quickly to relatively small changes in the accelerator pedal v. In a comfort-oriented design, a large ratio may be implemented, thus causing a sudden movement of the accelerator pedal 16 does not lead to a rapid change in engine torque Mmot. The gas pedal position v is the operator 15 supplied to calculate the coefficient of friction correction m. In this calculation can also enter into another map in which is deposited, which torque can be recorded or transmitted in existing environmental conditions such as temperature and humidity in particular in the contact area between the tire and the road.

In a gradient map 22 the slope a can be converted into a vehicle-dependent gradient correction. For example, in the case of a positive gradient a, that is to say when driving uphill, a lower drive torque can be transmitted from the wheels to the road in the case of a front-wheel drive vehicle, since the front wheels are relieved of load.

In a payload map 23 For example, a payload mzu can be converted into a corresponding payload correction value zk. The payload mzu can be determined, for example, at a level control, a headlamp leveling, a travel or other influenced by the loading units. With increased payload, this increases from the wheels 14 moment transferable to the street. Accordingly, the payload correction value zk can be increased with increased payload.

The target torque MSoll is applied to the control panel 18 and at the summit point 20 output. The control panel 18 is configured to control the motor torque Mmot.

The one from the first regulator 19 output value controls the actuator 9 in step 17 when there is a startup, which is in one step 38 is queried. In the starting process, the vehicle is stationary or it moves at a low speed vFzg and the clutch pedal 12 is released and, if necessary, the accelerator pedal 16 actuated.

If a sprint mode is active, then a second controller regulates 24 the actor 9 depending on a nominal slip Sset. The actual wheel slip SR can be calculated from the vehicle speed vFzg, a known wheel circumference and the wheel speed nR. SR = (nR - vFzg / Radumfangs) / (vFzg / Radumfangs)

By this regulation, the torque MR transmitted from the wheels to the road is controlled so high that the wheel slip SR is as close as possible to the setpoint slip Ssetpoint. The nominal slip S nominal is dimensioned so that the propulsion of the vehicle is as large as possible, the wheels 14 but still can transmit torque MR to the road. The setpoint slip Ssetpoint can be empirically determined on a new vehicle for supplied tire types or recalculated in occasional queries on a dry road.

The predetermined by the driver clutch pedal travel w can the actuator 9 regulate, if no start-up process is active nor after the setpoint torque Msoll is controlled. In this case, the clutch pedal travel w becomes one step 41 , if necessary via a clutch map 40 corrected, directly to the actuator 9 output.

Although some possible embodiments of the invention have been disclosed in the foregoing description, it is to be understood that numerous other variants of embodiments exist through the possibility of combining all of the cited and further all of the obvious technical features and embodiments. It is further understood that the embodiments are to be understood as examples only, which in no way limit the scope, applicability and configuration. Rather, the foregoing description would suggest a suitable way for the skilled person to realize at least one exemplary embodiment. It should be understood that in an exemplary embodiment, numerous changes in the function and arrangement of the elements may be made without departing from the scope and equivalents disclosed in the claims.

LIST OF REFERENCE NUMBERS

1

coupling system

2

clutch

3

engine

4

transmission

5

friction lining

6

feathers

7

cylinder

8th

piston

9

actuator

10

control unit

11

displacement sensor

12

clutch pedal

13

differential

14

wheel

15

operator

16

accelerator

17

Control field for actuating the actuator

18

control field

19

first controller

20

summing junction

21

Accelerator map

22

Gradient map

23

Zuladungskennfeld

24

second controller

25

Query the accelerator pedal position v

26

Inquiry of the slope a

27

Request the payload mzu

28

Query ambient temperature Tumg

29

rain query

30

Signal of traction control

31

Query if sprint mode is active

32

Polling the wheel slip

33

If, then operator

34

operator

35

torque limiter

36

Speed limit

37

summing junction

38

Detecting a start-up condition

39

If, then operator

40

Clutch pedal map

41

Polling the clutch pedal travel

a

pitch

zK

Zuladungs correction value

MLimit

torque delimitation

M mot

engine torque

MF

Driver target torque

MSoll

target torque

MR

wheel torque

nLimit

Speed limit

No

wheel speed

Ssoll

setpoint slip

SR

wheel slip

w

clutch pedal

v

accelerator

vFzg

vehicle speed

Claims (14)

Method for controlling an electromechanical clutch system in a motor vehicle, wherein the motor vehicle has a clutch ( 2 ), which via an actuator ( 9 ) can be opened and closed, wherein the actuator ( 9 ) mechanically by a clutch pedal ( 12 ) is decoupled, with the steps: - detecting a start-up state ( 38 ), - calculating a setpoint torque (Msoll), - controlling the motor torque (Mmot) to the setpoint torque (Msoll) and simultaneously controlling the actuator ( 9 ) to the smallest possible difference between the target torque (Msoll) and the engine torque (Mmot) regardless of a clutch travel (w) on the clutch pedal ( 12 ). The method of claim 1, wherein a slope (a) on which the vehicle is located, and wherein the target torque (Msoll) is increased at a positive slope (a). Method according to one of claims 1 and 2, wherein an additional load (mzu) of the vehicle is detected and wherein at additional load (mzu) the target torque (Msoll) is increased. Method according to one of Claims 1 to 3, in which a driver setpoint torque defined by an accelerator pedal position is determined, and a coefficient of friction correction value (mu) is determined which corresponds to the fraction of the driver-setpoint torque that can be transmitted to the lane, in which case that the proportion is less than 100%, the target torque (Msoll) is reduced. The method of claim 4, wherein the desired torque (Msetpoint) is reduced by a factor that is the ratio of road-going torque to driver-setpoint torque. Method according to claim 4 or 5, wherein in the presence of a rain intensity signal proportional to the rain intensity signal ( 29 ) the coefficient of friction correction (mü) is reduced. Method according to one of claims 4 to 6, wherein an ambient temperature (Tumg) is detected and wherein with increasing ambient temperature (Tumg) of the Reibwert-correctionwert (mü) is increased. Method according to one of claims 3 to 7, wherein a signal corresponding to the loading is detected and wherein in the presence of an additional load (mzu) of the Reibwert-correctionwert (mü) is increased. Method according to one of claims 4 to 8, wherein a traction signal of a traction control control unit is detected and in wheel slip of the coefficient of friction correction (mü) is reduced. A method according to claim 9, wherein the reduction of the coefficient of friction correction (mu) is inversely proportional to the strength of the traction signal. The method of claim 1, wherein in a sprint mode, a on a driven wheel ( 14 ) prevailing wheel slip (SR) is adjusted to a desired slip (S). Motor vehicle with a control unit ( 10 ), the control unit ( 10 ) has a memory means with a computer program stored thereon, wherein the computer program for carrying out a method according to one of claims 1 to 9 is configured. Computer program by carrying out a method according to one of Claims 1 to 11. A computer program product comprising program code means stored on a computer readable medium for performing the method of any one of the preceding claims 1 to 11 when the program code means are executed on a computer.

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