DE19751455A1 - Procedure for controlling automatic, electronic clutch for car - Google Patents

Abstract

The procedure uses a control parameter associated with a set point clutch capacity determined as a pilot value from a specified characteristic function between a control parameter of a clutch control system and a value corresponding to a clutch capacity. The clutch control system is pilot-controlled with this control parameter and a controller adjusts the control parameter corresponding to a comparison between set point and actual clutch capacity so that the specified set point clutch capacity arises. The steps are: Determination of an operating point of control parameter and the value corresponding to a clutch capacity and no, one or several further parameters upon which the clutch capacity depends, once after each transient of the controller or repeated after specified times; changing of a specified point of the characteristic function to an adapted point so that a distance between the specified point and the operating point reduces, and adaptation of the characteristic function to the adapted point and specified points of the characteristic function so that the adapted characteristic function replaces the original one.

Description

The invention relates to a method for regulating an automated clutch, in particular an electronically controlled clutch, in particular a motor vehicle, wherein from a predetermined characteristic function between a control variable Clutch control and at least one value corresponding to a clutch capacity a control variable belonging to a target clutch capacity as a pilot control value determines, the clutch control is piloted with this control variable and a Controller the control variable according to a comparison between target and actual Clutch capacity adjusts so that the predetermined target clutch capacity sets, according to the preamble of claim 1.

When regulating a clutch in such a way that a predetermined torque is transmitted , the clutch pressure is usually monitored to determine whether the value set by the controller via the control variable of the clutch control for the Clutch pressure corresponds to the actual clutch pressure. If this is not the case, it is a malfunction is detected and suitable countermeasures can be initiated. The expected value for the actual clutch pressure becomes conventional a characteristic curve between a control current for clutch control and a Removed clutch pressure.

Here, however, the problem arises that the characteristics of clutch-specific functions and for each individual coupling after assembly and, if necessary, after Integration, for example in a motor vehicle, must be determined separately. A Another problem is that the characteristic curves change overall due to aging Can shift clutch system. Especially when monitoring the Clutch pressure there are problems here because a detected malfunction of the Coupling may not actually be a malfunction, but only by one a characteristic curve that does not correspond to the current operating situation is incorrect  The expected value for the clutch pressure is specified. To avoid such False triggering of the monitoring function must be complicated and time-consuming Error value handling takes place.

Furthermore, the non-optimal characteristic curve has the disadvantage that pilot control values are not optimal be selected and thus the controller long periods of time and a large range must settle until the regulation has settled. This has the disadvantage that the Regulation must be designed very powerful in order to avoid large deviations from To be able to regulate the setpoint in a stable, steady area and not in to reach an unstable, vibrating area. The long settling times lead furthermore to an uncomfortable driving behavior with possibly increased fuel consumption, since a mismatch of the clutch, possibly with a changed torque delivery Drive motor must be balanced.

The present invention is therefore based on the object of an improved method to provide the above type, the above disadvantages be overcome and a reliable and reliable clutch control is guaranteed.

This object is achieved according to the invention by a method of the above. Kind with the in claim 1 marked features solved. Advantageous embodiments of the invention are in the dependent claims specified.

The following steps are provided for this purpose according to the invention:

• a) Determining an operating point of the control variable and one Value corresponding to the clutch capacity after each settling of the controller,
• b) changing a predetermined point of the identification function to an adapted point such that there is a distance between the predetermined point of the identification function and the operating point is reduced, and
• c) adapting the characteristic function to the adapted point and predetermined points of the Identification function in such a way that the adapted identification function replaces the original one.

This has the advantage that an even better and more precise regulation by a more precise one Pre-tax value is realized, which leads to less wear and reduction of Malfunctions. Furthermore, there is a more precise expected value for a clutch pressure can be determined since the identification function is permanently adapted during operation. This eliminates particularly tight manufacturing tolerances for the coupling system and leads to one corresponding cost reduction, since these tolerances of the invention Characteristic curve adaptation can be compensated.

In an advantageous development of the invention, the following additional steps are also provided:

• a) determining boundary values of the adapted characteristic function at predetermined Control variables or at predetermined reference values of a clutch capacity corresponding values; and or
• b) storing the boundary values in a memory.

The predetermined control variables are a minimum and a maximum Control variable or the predetermined reference values a minimum and a maximum Value of values corresponding to a clutch capacity.

A minimal amount of memory for securing an adapted characteristic is achieved in that when the control is restarted, the characteristic function from the boundary values is new is determined. This means that only the boundary values have to be saved and not the Points of the adapted identification function itself.

The clutch capacity is expediently made up of the engine torque and one Speed difference between an input side and an output side of the clutch certainly.

In a particularly preferred manner, the target clutch capacity is selected such that a predetermined torque, especially engine torque, from the clutch is transmitted.  

A limited computing effort for characteristic curve adaptation is achieved by the fact that the Control variable and / or the value corresponding to a clutch capacity and if necessary, further sizes, on which the clutch capacity depends, in ranges is divided, with each area having a focus on the identification function is assigned and the operating point determined in step (a) to that Center of gravity is assigned, in the area of which the operating point lies.

The predetermined point of the characteristic function in step (b) is expediently the the center of gravity assigned to the operating point determined in step (a).

To avoid having to adapt two to a common area boundary areas of focus that lie one on top of the other an adaptation of the identification function make impossible, are three, four or more areas with three, four or more Priority areas provided. So there are always at least two Center of gravity spaced apart and define as a characteristic function at least one straight line.

The predetermined points of the characteristic function of are also expedient Step (c) the focus areas without the adapted focus area.

To save storage space, in a particularly preferred manner Restart the control the area focus from the characteristic function as points this in redefined the respective areas. This means that the Areas of focus unnecessary.

In a preferred embodiment, a distance is referred to as a distance in step (b) of the value corresponding to the clutch capacity and a distance with respect to the Control variable between the predetermined point of the characteristic function and the Operating point determined and reduced in each case. For example, this corresponds to one Abscissa and ordinate spacing.

To achieve small adaptation steps, so that short-term extreme situations or outliers do not immediately falsify the characteristic or adapt the characteristic quickly  Avoiding an actual excessive clutch pressure is particularly important preferably the operating point before step (b) of digital low-pass filtering subjected. This corresponds, for example, to multiplying the distance by predetermined point and operating point with a predetermined value between zero and one.

The characteristic function is expediently a straight line or a non-linear function in the two-dimensional space, a flat or curved surface in three-dimensional space or a surface in n-dimensional space. The two-dimensional one is preferred Space of a control variable, a disturbance variable, i.e. another variable, of which the Coupling capacity depends, and one corresponding to the capacity of the clutch Value spanned, the three-dimensional space of one control variable and two of the Capacity of the coupling spanned corresponding values and the n-dimensional space of a control variable, n-2 disturbance variables and one of the capacity of the clutch corresponding values spanned.

In a preferred embodiment, the clutch control is hydraulic, which Control variable a current I of the clutch control and / or that of a clutch capacity corresponding value a clutch pressure p, preferably a predetermined minimum Value is 0 bar and a predetermined maximum value is 10 bar. The clutch pressure is p additionally divided into areas in an advantageous manner. This includes, for example first range clutch pressures less than 3.0 bar, second range clutch pressures of 3.0 bar <= p <4.5 bar, a third range clutch pressures of 4.5 <= p <6.0 bar and a fourth area clutch pressures greater than or equal to 6.0 bar.

One of a clutch capacity, i. H. a transmitted moment, corresponding value one also derives one from an engine torque signal (MMI signal), for example Engine control unit. To do this, take advantage of the fact that in certain Operating phases transmit a stationary torque output by a drive motor is, for example with a slipping clutch and constant engine speed and constant slip.

The disturbance variables preferably additionally include a temperature value of the clutch.  

In a particularly preferred manner, the characteristic function is adapted in step (c) by means of linear regression or the Gaussian least squares method.

A direct determination of a torque transmission through the clutch from one Driving torque is achieved by that corresponding to a clutch capacity Value is an output signal, in particular a pressure signal, of a torque sensor.

An adaptation of a predetermined range is excluded by at least that a predetermined point of the identification function is fixed. This has the advantage that one in critical areas where one can possibly actually transfer the Cannot determine the moment precisely enough, prevents incorrect adaptation.

The predetermined fixed point is expediently a center of gravity or a Point of the identification function at maximum or minimum control variable or a point of Identification function at maximum or minimum corresponding to a clutch capacity Value.

An adaptation of areas of the identification function in which one can see the actual Coupling capacity can not determine with sufficient accuracy, is prevented that for different areas of the identification function different sources for one Coupling capacity corresponding value can be used.

Further features, advantages and advantageous configurations of the invention result from the dependent claims, as well as from the following description of the invention based on the attached drawings. These show in

Fig. 1 is a schematic block diagram of a control of an electronically controlled clutch and

Fig. 2 is a graph illustrating the characteristic curve adaptation according to the invention.

The clutch slip control unit shown by way of example in FIG. 1 comprises a controller 10 , which determines a clutch actuating torque from the engine torque and the deviation from the setpoint and actual slip, which in a function block 12 with the characteristic curve 14 generates a control current I for a hydraulic system 16 of the clutch 18 determined. With this control current I, the hydraulics 16 are controlled and the clutch 18 transmits a torque, since a certain instantaneous clutch capacity is set by means of the hydraulics 16 . Clutch capacity is to be understood here as a maximum torque that can currently be transmitted by the clutch. The actual value of the slip of the clutch is fed back via connection 20 and compared in function block 22 with a target value. In accordance with the result of this comparison, the controller 10 regulates the control current of the hydraulics 16 until the regulation has settled and the desired torque is transmitted from the clutch.

The description of the invention, there is here only by way of example with reference to a control, which as a corresponding value of a clutch capacity, the engine torque and as a control variable for the clutch controller 16, a driving current I 16 of the hydraulic used. The characteristic curve 14 of the clutch can also be composed of other values, such as the clutch pressure, a travel path of a servomotor and a pressure value of a torque sensor. In addition, the characteristic curve 14 can also be an area in three-dimensional or multidimensional space, the additional dimensions being generated by additional values, such as a temperature value, for example of a transmission. This parameter affects the relationship between the clutch capacity and a control variable, such as the control current I.

FIG. 2 shows a characteristic curve 14 by way of example . The method according to the invention is to be explained in more detail below with reference to this FIG. 2. After the above-mentioned settling of the control of the clutch 18 , an operating point is determined in the two-dimensional pI space shown here by way of example, ie a pair of values from the current clutch pressure p and the current desired clutch current I. Instead of the desired current, the actual current can alternatively be used. Depending on the current clutch pressure value p, the operating point determined in this way is assigned to exactly one of 4 areas. The range limits were chosen here as an example:

Range 1: p <3.0 bar
Range 2: 3.0 bar <= p <4.5 bar
Range 3: 4.5 bar <= p <6.0 bar
Range 4: 6.0 bar <= p

A focal point 24 , 26 , 28 and 30 is predetermined for each area. The center of gravity of the area in which a current operating point falls is shifted a little in the direction of the current operating point and thus an adapted center of gravity is generated. For this purpose, a digital low-pass function with the same time constant is carried out for each of the two coordinates. The parameters of the low-pass filtering are to be selected in such a way that, in the event of an impermissibly high pressure, adaptation is not carried out so quickly that the characteristic curve 14 is adjusted to the excess pressure before a monitoring function responds. From the 4 areas of focus 24 , 26 , 28 and 30 , which do not necessarily lie exactly on a straight line, a straight line as an adapted characteristic function or characteristic curve, for example, is determined using the least squares method, for example, which corresponds to the adapted area of focus 24 , 26 , 28 and 30 is closest.

The straight line 14 represents the adapted characteristic curve 14 sought and is given by 2 points, namely a current value 32 at a fixed reference pressure of 0 bar and a current value 34 at a fixed reference pressure of 10 bar. Only these two current values 32 and 34 have to be written into an EEPROM, for example, in order to store the characteristic curve, but not all the focal points 24 , 26 , 28 and 30. This saves storage space accordingly. After switching the computer off and then on again, initialization values for the focal points 24 , 26 , 28 and 30 can be calculated therefrom.

In FIG. 2, 36 , 38 , 40 and 42 denote areas or adaptation areas in which the respective center of gravity shift by adaptation and thus lead to a shift in the straight line or characteristic curve 14 . Corresponding to the different adapted characteristic curves 14 , there are a plurality of minimum and maximum current values 32 and 34 in each case .

In principle, either the desired clutch or the actual coupling current can be used. The use of the target current has the advantage that the plausibility between target and actual current in a clutch pressure monitoring with can be included.  

The tracking of a center of gravity 24 , 26 , 28 and 30 requires little computing time and is preferably carried out at about 100 Hz. The calculation of the characteristic curve 14 from the center of gravity 24 , 26 , 28 and 30 is carried out, for example, every 0.1 to 1.0 s. The calculation can be broken down into several sections, which can be distributed over several scanning steps, for example, in order to load a computer more evenly.

In the characteristic curve adaptation according to the method according to the invention, the adaptation of center of gravity in the range of low values of a value corresponding to a clutch capacity, for example a range at low clutch pressures p, can be improved by using an output signal of a torque sensor instead of the MMI signal. As a result, errors in the MMI signal are excluded in these areas and a corresponding error in the adaptation of the identification function 14 is avoided.

The range of low values of a value corresponding to a clutch capacity, for example a range at low clutch pressures p, is very important for comfortable clutch control or regulation. Thus, a clutch pre-filling takes place when starting, which on the one hand must be quick, but on the other hand must not take place too strongly, since an uncomfortable starting jerk would occur due to a sudden and undesirable torque transmission of the clutch. Furthermore, highly dynamic phases should be avoided when controlling the clutch. A control variable for the pre-filling and the pilot control of the clutch is taken directly from the characteristic function or the characteristic curve 14 , so that a well and error-free adapted characteristic function 14 reliably eliminates this problem in the area mentioned with an output signal of a torque sensor as a value corresponding to a clutch capacity.

The torque sensor is a hydraulic component that controls the contact pressure of the conical pulleys of a variator of a continuously variable transmission (so-called CVT transmission) as a function of a torque to be transmitted. The output signal of the torque sensor is usually a pressure which is sensed or measured and which provides a measure of a torque which is actually actually transmitted. Using the clutch characteristic function or clutch characteristic curve 14, the controller 10, a clutch torque M _soll and the actual instantaneous torque M _is measured by the torque sensor. The operating point obtained in this way is used with the inventive method described above for adapting the characteristic function.

In an advantageous development of the invention, a predetermined point of the identification function is always held fixed, so that no adaptation of points of the identification function 14 takes place in the corresponding area. The predetermined point is, for example, a center of gravity 24 , 26 , 28 , 30 or a point of the characteristic function with a maximum or minimum control variable or a point of the characteristic function with a maximum or minimum value corresponding to a clutch capacity.

In another preferred development of the invention, different sources for the value corresponding to a clutch capacity are used for different areas of the identification function 14 with, for example, corresponding area focal points 24 , 26 , 28 and 30 . For example, the output signal of the torque sensor is used for adapting points of the characteristic curve or for determining operating points in areas of low control variables and the MMI signal for adapting points of the characteristic curve in areas of high control variables or vice versa.

Reference list

10th

Regulator

12th

Function block

14

curve

16

Hydraulics

18th

clutch

20th

connection

22

Function block

24th

Area focus

26

Area focus

28

Area focus

30th

Area focus

32

min. Current value

34

Max. Current value

36

Adaptation area

38

Adaptation area

40

Adaptation area

42

Adaptation area
Driving current
pClutch pressure

Claims (34)

1. A method for regulating an automated clutch, in particular an electronically controlled clutch, in particular a motor vehicle, wherein from a predetermined characteristic function between a control variable of a clutch control and a value corresponding to a clutch capacity, a control variable belonging to a target clutch capacity determines the pilot control value with the clutch control this actuating variable is precontrolled and a controller regulates the actuating variable in accordance with a comparison between the target and actual clutch capacity in such a way that the predetermined target clutch capacity is established, characterized by the following steps,

• a) determining an operating point of the control variable and the value corresponding to a clutch capacity and none, one or more further variables on which the clutch capacity depends, once after each settling of the controller or repeatedly after predetermined times,
• b) changing a predetermined point of the characteristic function to an adapted point such that a distance between the predetermined point of the characteristic function and the operating point is reduced, and
• c) adapting the identification function to the adapted point and predetermined points of the identification function such that the adapted identification function replaces the original one.

2. The method according to claim 1, characterized by the following additional step,

• a) Determination of boundary values of the adapted characteristic function with predetermined control variables or with predetermined reference values of the values corresponding to a clutch capacity.

3. The method according to claim 2, characterized in that the predetermined control variables a minimum and a maximum control variable or the predetermined reference values have a minimum and a maximum value of values corresponding to a clutch capacity. 4. The method according to claim 2 or 3, characterized by the following additional step,

• a) Saving the boundary values in a memory.

5. The method according to any one of claims 2 to 4, characterized in that when the control is restarted, the characteristic function from the boundary values is new is determined. 6. The method according to any one of the preceding claims, characterized in that a deviation of the target and actual clutch capacity from a speed difference between a drive side and an output side of the clutch is determined. 7. The method according to any one of the preceding claims, characterized in that the target clutch capacity is selected such that a predetermined one Torque, in particular engine torque, is transmitted from the clutch. 8. The method according to any one of the preceding claims, characterized in that the control variable and / or the value corresponding to a clutch capacity and if necessary, further sizes, on which the clutch capacity depends, in Areas is divided, with each area having a focus on the Characteristic function is assigned and the operating point determined in step (a) is assigned to the area focus in the area of which Operating point is.   9. The method according to claim 8, characterized in that the predetermined point of the identification function in step (b) that of step (a) specific operating point is assigned to the center of gravity. 10. The method according to any one of claims 8 or 9, characterized in that three, four or more areas with three, four or more areas of focus are provided. 11. The method according to any one of claims 8 to 10, characterized in that the predetermined points of the characteristic function of step (c) are the center of gravity without the focus area just adapted. 12. The method according to any one of claims 8 to 11, characterized in that when restarting the control, the main areas of focus from the identification function as Points of this are newly determined in the respective areas. 13. The method according to any one of the preceding claims, characterized in that in step (b) as a distance a distance with respect to the clutch capacity corresponding at least one value and a distance with respect to the Control size and, if necessary, distances with respect to other sizes, of which the clutch capacity depends between the predetermined point of the Characteristic function and the operating point is determined and reduced in each case. 14. The method according to any one of the preceding claims, characterized in that the operating point is subjected to digital low-pass filtering before step (b). 15. The method according to claim 14,  characterized in that low pass filtering a multiplication of the distance from predetermined point and Operating point with a predetermined value between zero and one corresponds. 16. The method according to any one of the preceding claims, characterized in that the characteristic function is a straight line or a non-linear function in two dimensions Space, a flat or curved surface in three-dimensional space or a Area in n-dimensional space. 17. The method according to claim 16, characterized in that the two-dimensional space of a drive size and one of the capacity the value corresponding to the coupling is clamped. 18. The method according to claim 16, characterized in that the three-dimensional space of a drive size and one of the capacity the coupling corresponding value and another size, of which the Coupling capacity depends, e.g. B. the temperature is spanned. 19. The method according to claim 16, characterized in that the n-dimensional space of a control variable and one of the capacitance of the Coupling corresponding value and n-2 other sizes, of which the Coupling capacity depends, is spanned. 20. The method according to any one of the preceding claims, characterized in that the clutch control is hydraulic. 21. The method according to any one of the preceding claims, characterized in that the control variable is a current I of the clutch control.   22. The method according to any one of the preceding claims, characterized in that the value corresponding to a clutch capacity is a clutch pressure p. 23. The method according to claim 22, characterized in that a predetermined minimum value 0 bar and a predetermined maximum value 10 is cash. 24. The method according to claim 22 or 23, characterized in that the clutch pressure p is divided into areas. 25. The method according to claim 24, characterized in that a first range clutch pressures less than 3.0 bar, a second range Coupling pressures of 3.0 bar <= p <4.5 bar, a third range coupling pressures of 4, 5 <= p <6.0 bar and a fourth range clutch pressures greater than or equal to 6.0 bar included. 26. The method according to any one of the preceding claims, characterized in that the values corresponding to a clutch capacity also have a value comprise, which corresponds to a pressure change in the clutch over time. 27. The method according to any one of the preceding claims, characterized in that other sizes, on which the clutch capacity depends, a temperature value include. 28. The method according to any one of the preceding claims, characterized in that  the values corresponding to a clutch capacity also include an aging value include the clutch. 29. The method according to any one of the preceding claims, characterized in that the adaptation in step (c) by means of linear regression or according to the Gaussian Least squares method is done. 30. The method according to any one of the preceding claims, characterized in that the value corresponding to a clutch capacity is an output signal, in particular is a pressure signal, a moment sensor. 31. The method according to any one of the preceding claims, characterized in that at least one predetermined point of the identification function is fixed. 32. The method according to claim 31, characterized in that the predetermined fixed point is a center of gravity or a point of Identification function at maximum or minimum control variable or a point of Identification function at maximum or minimum clutch capacity corresponding value. 33. The method according to any one of the preceding claims, characterized in that for different areas of the identification function different sources for one Coupling capacity corresponding value can be used. 34. The method according to any one of the preceding claims, characterized in that the value corresponding to a clutch capacity from a Motor torque value, at the border between adhesion and slip or at low slip operated clutch, is determined.