DE19751455B4 - Method for controlling an automated clutch - Google Patents

Abstract

A method for controlling an automated clutch, wherein from a predetermined characteristic between a control variable of a clutch control and a clutch capacity corresponding value to a target clutch capacity associated control variable as pre-control value, the clutch control is precontrolled with this control variable and a controller, the control variable according to a comparison between set and actual clutch capacities such that the predetermined setpoint clutch capacity is established, characterized by the following steps: (a) determining an operating point from a desired drive quantity and the value corresponding to the clutch capacity, once after each settling of the controller, b) changing a predetermined point of the characteristic to an adapted point such that a distance between the predetermined point of the characteristic and the operating point decreases, and (c) adapting the characteristic to the adapted point and predetermined points of the characteristic such that the adapted characteristic replaces the original one.

Description

The invention relates to a method for controlling an automated clutch, in particular an electronically controlled clutch, in particular of a motor vehicle, wherein from a predetermined characteristic between a control variable of a clutch control and at least one value corresponding to a clutch capacity determined to a desired clutch capacity control variable as pre-control value, the clutch control is precontrolled with this drive quantity and a controller adjusts the drive variable in accordance with a comparison between the setpoint and actual clutch capacities in such a way that the predetermined setpoint clutch capacity adjusts, in accordance with the preamble of claim 1.

In the control of a clutch such that a predetermined torque is transmitted, is carried out according to knowledge of the practice usually monitoring the clutch pressure to see whether the controller set via the control variable of the clutch control value for the clutch pressure corresponds to the actual clutch pressure. If this is not the case, then a malfunction is detected and suitable countermeasures can be initiated. The expectation value for the actual clutch pressure is conventionally taken from a characteristic between a control current for the clutch control and a clutch pressure.

Here, however, there is the problem that the characteristics are clutch-specific functions and must be determined separately for each clutch after assembly and possibly after integration, for example, in a motor vehicle. Another problem is that the characteristics may shift due to aging throughout the coupling system. Especially in the monitoring of the clutch pressure, there are problems here, as a detected malfunction of the clutch may actually not be a malfunction, but only by a not the current operating situation corresponding characteristic is given a false expectation value for the clutch pressure. To avoid such false triggering of the monitoring function complicated and expensive error value treatments must be done.

Furthermore, the non-optimal characteristic has the disadvantage that pre-control values are not optimally selected and thus the controller must compensate long periods of time and a large range until the control has settled. This has the disadvantage that the control must be designed very powerful, even in large deviations from the setpoint in a stable, steady-state range to be able to control and not to get into an unstable, oscillating range. The long settling times also lead to an uncomfortable driving behavior with possibly increased fuel consumption, since a mismatch of the clutch is possibly compensate for a changed torque output of a drive motor.

From the DE 44 09 122 A1 For example, a device and a method for regulating a starting device are known. For this purpose, the starting process is carried out in two phases, namely in a first phase, in which the input speed is guided to a desired speed, and in a subsequent second phase in which a formed from the difference between input speed and output speed differential speed signal a predetermined desired course to is tracked to the value zero. In the concrete version, this technique is extremely expensive.

Furthermore, still on the EP 0 494 608 A2 referenced as relevant prior art.

The present invention is therefore based on the object to provide an improved method of the type mentioned above, wherein the above-mentioned disadvantages are overcome and a reliable and reliable coupling control is ensured.

This object is achieved by a method of o. G. Art solved with the features characterized in claim 1. Advantageous embodiments of the invention are specified in the dependent claims.

• (a) Bestimmen eines Betriebspunktes von Ansteuergröße und dem einer Kupplungskapazität entsprechenden Wert nach jedem Einschwingen des Reglers,
• (b) Verändern eines vorbestimmten Punktes der Kennfunktion auf einen adaptierten Punkt derart, dass sich ein Abstand zwischen dem vorbestimmten Punkt der Kennfunktion und dem Betriebspunkt verringert, und
• (c) Adaptieren der Kennfunktion an den adaptierten Punkt und vorbestimmte Punkte der Kennfunktion derart, dass die adaptierte Kennfunktion die ursprüngliche ersetzt.

For this purpose, the following steps are provided according to the invention:

• (a) determining an operating point of drive quantity and the value corresponding to a clutch capacity after each settling of the controller,
• (b) changing a predetermined point of the characteristic to an adapted point such that a distance between the predetermined point of the characteristic and the operating point decreases, and
• (c) adapting the identification function to the adapted point and predetermined points of the identification function such that the adapted identification replaces the original one.

This has the advantage that an even better and finer control is realized by a more accurate pilot control value, which leads to less wear and reduction of malfunction. Furthermore, a more exact expected value for a clutch pressure can be determined, since the characteristic is permanently adapted during operation. This eliminates particularly tight manufacturing tolerances for the coupling system and leads to a corresponding cost reduction, since these tolerances are compensated by the characteristic adaptation according to the invention.

• (d) Bestimmen von Randwerten der adaptierten Kennfunktion bei vorbestimmten Ansteuergrößen oder bei vorbestimmten Referenzwerten der einer Kupplungskapazität entsprechenden Werte; und/oder
• (e) Abspeichern der Randwerte in einen Speicher.

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

• (d) determining boundary values of the adapted characteristic at predetermined drive values or at predetermined reference values of the values corresponding to a clutch capacity; and or
• (e) storing the boundary values in a memory.

Here, the predetermined drive quantities are a minimum and a maximum drive quantity or the predetermined reference values are a minimum and a maximum value of values corresponding to a clutch capacity.

A minimum storage effort for securing an adapted characteristic curve is achieved by re-determining the characteristic from the boundary values when the control is restarted. As a result, only the boundary values need to be stored and not the points of the adapted characteristic itself.

Conveniently, the clutch capacity is determined from the engine torque and a speed difference between a drive side and an output side of the clutch.

In a particularly preferred manner, the desired clutch capacity is selected such that a predetermined torque, in particular engine torque, is transmitted from the clutch.

A limited calculation effort for characteristic curve adaptation is achieved by subdividing the control variable and / or the value corresponding to a clutch capacity and possibly further variables on which the clutch capacity is dependent, to each range having a range center of gravity on the characteristic function and in step (A) certain operating point is assigned to that area center of gravity, in the area of which the operating point lies.

In this case, the predetermined point of the characteristic function in step (b) is expediently the area center of gravity assigned to the operating point determined in step (a).

In order to avoid that, in the adaptation, two center areas coming to lie on a common area boundary make an adaptation of the characteristic impossible, three, four or more areas with three, four or more area centers are provided. Thus, at least two area centers always remain spaced apart and define at least one line as a characteristic.

Furthermore, the predetermined points of the characteristic function of step (c) are expediently the range centroids without the adapted centroid.

In order to save storage space, the range centers of gravity from the characteristic function are redetermined as points of these in the respective areas in a particularly preferred manner when the controller is restarted. As a result, a separate storage of the area centers is unnecessary.

In a preferred embodiment, in step (b) a distance is determined as the distance with respect to the clutch capacity corresponding value and a distance with respect to the driving variable between the predetermined point of the characteristic and the operating point and respectively reduced. This corresponds, for example, to an abscissa and an ordinate distance.

In order to achieve small adaptation steps so that short-term extreme situation or outliers do not immediately distort the characteristic or to avoid rapid adaptation of the characteristic to an actual excessive clutch pressure, the operating point before step (b) is subjected to digital low-pass filtering in a particularly preferred manner. This corresponds for example to a multiplication of the distance of predetermined point and operating point with a predetermined value between zero and one.

Expediently, the characteristic function is a straight line or a non-linear function in two-dimensional space, a plane or curved surface in three-dimensional space, or a surface in n-dimensional space. In this case, the two-dimensional space is preferably spanned by a drive variable, a disturbance variable, that is to say a further variable on which the clutch capacity depends, and by a value corresponding to the capacity of the clutch, the three-dimensional space by a drive variable and two values corresponding to the capacity of the clutch spanned and the n-dimensional space spanned by a control variable, n - 2 disturbances and of the capacity of the clutch corresponding values.

In a preferred embodiment, the clutch control is a hydraulic system, the control variable is a current I of the clutch control and / or the value corresponding to a clutch capacity a clutch pressure p, preferably a predetermined minimum value is 0 bar and a predetermined maximum value is 10 bar. The clutch pressure p is additionally advantageously divided into areas. Here, for example, a first range clutch pressures smaller than 3.0 bar, a second range of clutch pressures of 3.0 bar <= p <4.5 bar, a third range of clutch pressures of 4.5 <= p <6.0 bar and a fourth Range of coupling pressures greater than or equal to 6.0 bar.

One of a clutch capacity, d. H. a transmitted torque, corresponding value is derived, for example, from an engine torque signal (MMI signal) of an engine control unit. For this purpose, one makes use of the circumstance that in certain operating phases, a stationary torque output by a drive motor is transmitted, for example in the case of a slipping clutch and a constant engine speed and constant slip.

The disturbance variables preferably additionally comprise a temperature value of the coupling.

In a particularly preferred manner, the adaptation of the characteristic function in step (c) takes place by means of linear regression or according to the Gaussian least squares method.

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

An adaptation of a predetermined range is excluded by the fact that at least one predetermined fixed point of the characteristic function is held. This has the advantage that in critical areas where one may possibly not be able to determine the actual transmitted moment accurately enough, a misadaptation is prevented.

Conveniently, the predetermined fixed point is a range centroid or a point of the characteristic at maximum or minimum drive magnitude or a point of the characteristic at maximum or minimum of a clutch capacity corresponding value.

An adaptation of ranges of the characteristic in which one can not determine the actual clutch capacity with sufficient accuracy is prevented by using different sources for the clutch capacity corresponding value for different ranges of the characteristic.

Further features, advantages and advantageous embodiments of the invention will become apparent from the dependent claims, and from the following description of the invention with reference to the accompanying drawings. These show in

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

2 a graphic illustration of the characteristic adaptation according to the invention.

In the 1 Clutch slip control unit shown by way of example includes a controller 10 , Which determines from the engine torque and the deviation of the target and actual slip a clutch actuating torque that in a function block 12 with the characteristic 14 a drive current I for a hydraulic 16 the clutch 18 certainly. With this drive current I, the hydraulics 16 controlled and the clutch 18 transmits a torque because by means of the hydraulics 16 a certain instantaneous clutch capacity is set. Coupling capacity is to be understood herein as meaning a maximum torque that can currently be transmitted by the clutch. The actual value of the slip of the clutch is via connection 20 returned and in function block 22 compared with a setpoint. The controller regulates according to the result of this comparison 10 the drive current of the hydraulics 16 until the control has settled and the desired torque is transmitted from the clutch.

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

2 shows an example of a characteristic 14 , Based on this 2 the method of the invention will be explained in more detail below. 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 value pair consisting of the current clutch pressure p and the current desired clutch power I. Instead of the desired current, alternatively, the actual current can be used. Depending on the current clutch pressure value p, the operating point determined in this way is assigned to exactly one of 4 ranges. The range limits were chosen here as an example as follows: Area 1 p <3.0 bar Area 2 3.0 bar <= p <4.5 bar Area 3 4.5 bar <= p <6.0 bar Area 4 6.0 bar <= p

For each area is an area focus 24 . 26 . 28 and 30 predetermined. The area center of gravity of the area into which a current operating point falls is shifted a bit in the direction of the current operating point, thus producing an adapted area center of gravity. For this purpose, a digital low-pass function with the same time constant is executed for each of the two coordinates. The parameters of the low-pass filtering are to be chosen such that in the case of an impermissibly high pressure is not adapted so fast that the characteristic 14 before responding to a monitoring function tracked to the high pressure. From the 4 main areas 24 . 26 . 28 and 30 , which are not necessarily exactly on a straight line, then, for example, a straight line is determined by means of, for example, the least squares method as an adapted characteristic or characteristic which corresponds to the adapted range centroid 24 . 26 . 28 and 30 is closest.

Straight 14 represents the sought adapted characteristic 14 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 must be written to save the characteristic, for example, in an EEPROM, but not all area priorities 24 . 26 . 28 and 30 , This saves space accordingly. After switching the computer off and on again, initialization values for the main areas of focus can be obtained 24 . 26 . 28 and 30 be calculated.

In 2 are with 36 . 38 . 40 and 42 Designated areas or adaptation areas in which the respective area centers shift by adaptation and thus to a shift of the line or characteristic curve 14 to lead. According to the different adapted characteristics 14 There are a plurality of minimum and maximum current values, respectively 32 and 34 ,

In principle, either the nominal coupling or the actual coupling current can be used for the method according to the invention. The use of the desired current has the advantage that the plausibility between desired and actual current can be included in a clutch pressure monitoring.

The tracking of each area priority 24 . 26 . 28 and 30 requires little computing time and preferably takes place at about 100 Hz. The calculation of the characteristic curve 14 from the main areas 24 . 26 . 28 and 30 For example, every 0.1 to 1.0 s is performed. The calculation can be divided into several sections, which can be distributed over several sampling steps, for example, in order to load a computer more evenly.

In the characteristic adaptation according to the method according to the invention, the adaptation of range centers in the range of low values of a clutch capacity corresponding value, so 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 of the MMI signal are excluded in these areas and a corresponding e error in the adaptation of the characteristic 14 avoided.

Especially the range of low values of a value corresponding to a clutch capacity, that is, for example, a range at low clutch pressures p, is very important for a comfortable clutch control. Thus, when starting a Kupplungsvorbefüllung, on the one hand must be done quickly, but on the other hand must not be too strong, as a sudden and unwanted torque transmission of the clutch would cause an uncomfortable starting pressure. Furthermore, highly dynamic phases are to be avoided in the clutch control. A control variable for the pre-filling and the pilot control of the clutch is directly the characteristic or the characteristic 14 taken, so that a well and error-free adapted characteristic 14 in the said range with an output of a torque sensor as a value corresponding to a clutch capacity, this problem is reliably eliminated.

The torque sensor is a hydraulic component, which controls a contact pressure of conical disks of a variator of a continuously variable transmission (so-called CVT transmission) in dependence on a torque to be transmitted. The output signal of the torque sensor is usually a pressure which is sensed and provides a measure of a momentarily actually transmitted torque. Using the clutch characteristic or clutch characteristic 14 represents the regulator 10 a clutch torque M _{is supposed to be} and the actual actual torque M _ist is measured by means of the torque sensor. The operating point thus obtained is used with the above-described method according to the invention for adapting the characteristic function.

In an advantageous embodiment of the invention, a predetermined point of the characteristic is always fixed fixed, so that in the corresponding area no adaptation of points of the characteristic 14 he follows. The predetermined point is, for example, a range centroid 24 . 26 . 28 . 30 or a point of the characteristic at maximum or minimum control variable or a point of the characteristic at maximum or minimum coupling capacity corresponding value.

In another preferred embodiment of the invention are for different areas of the characteristic 14 with, for example, corresponding area priorities 24 . 26 . 28 and 30 uses different sources for the value corresponding to a clutch capacity. For example, the output signal of the torque sensor is used for the adaptation of points of the characteristic curve or for the determination of operating points in regions of low actuation variables, and the MMI signal for the adaptation of points of the characteristic curve in regions of high actuation variables or vice versa.

LIST OF REFERENCE NUMBERS

10

regulator

12

function block

14

curve

16

hydraulic

18

clutch

20

connection

22

function block

24

Area focus

26

Area focus

28

Area focus

30

Area focus

32

minute current value

34

Max. current value

36

adaptation range

38

adaptation range

40

adaptation range

42

adaptation range

I

driving

p

clutch pressure

Claims (38)

A method for controlling an automated clutch, wherein from a predetermined characteristic between a control variable of a clutch control and a clutch capacity corresponding value to a target clutch capacity associated control variable as pre-control value, the clutch control is precontrolled with this control variable and a controller, the control variable according to a comparison adjusted between desired and actual clutch capacity such that the predetermined target clutch capacity is established, characterized by the following steps, (a) determining an operating point from a target drive quantity and the value corresponding to the clutch capacity, once after each settling of the controller, (b) changing a predetermined point of the characteristic to an adapted point such that a distance between the predetermined point of the characteristic and the operating point decreases, and (c) adapting the identification function to the adapted point and predetermined points of the identification function such that the adapted identification replaces the original one. A method according to claim 1, characterized in that in step (a) further sizes are taken into account, on which the coupling capacity depends. Method according to claim 1 or 2, characterized by the following additional step, (d) determining boundary values of the adapted characteristic at predetermined drive values or at predetermined reference values of the values corresponding to a clutch capacity. Method according to Claim 3, characterized in that the predetermined drive variables are a minimum and a maximum drive variable or the predetermined reference values are a minimum and a maximum value of values corresponding to a clutch capacity. Method according to claim 3 or 4, characterized by the following additional step, (e) storing the boundary values in a memory. Method according to one of Claims 3 to 5, characterized in that the characteristic function is newly determined from the boundary values when the control system is restarted. Method according to one of the preceding claims, characterized in that a deviation from the setpoint and actual clutch capacity is determined from a speed difference between a drive side and an output side of the clutch. Method according to one of the preceding claims, characterized in that the desired clutch capacity is selected such that a predetermined engine torque is transmitted from the clutch. Method according to one of the preceding claims, characterized in that the desired control quantity and / or the clutch capacity corresponding value and optionally other sizes on which the clutch capacity depends, are divided into areas, each area assigned a center of gravity on the characteristic and the operating point determined in step (a) is assigned to the area center of gravity in whose area the operating point lies. A method according to claim 9, characterized in that the predetermined point of the characteristic function in step (b) is the range center of gravity assigned to the operating point determined in step (a). Method according to one of claims 9 or 10, characterized in that three, four or more areas are provided with three, four or more area centers. Method according to one of Claims 9 to 11, characterized in that the predetermined points of the characteristic function of step (c) are the range centroids without the currently adapted range centroid. Method according to one of Claims 9 to 12, characterized in that, when the control is restarted, the range centers of gravity from the characteristic function are redetermined as points in the respective areas. Method according to one of the preceding claims, characterized in that in step (b) as distance a distance with respect to the coupling capacity corresponding at least one value and a distance with respect to the control variable and optionally distances with respect to other sizes on which the clutch capacity depends between the predetermined Point of the characteristic and the operating point is determined and respectively reduced. Method according to one of the preceding claims, characterized in that the operating point before step (b) is subjected to a digital low-pass filtering. A method according to claim 15, characterized in that the low-pass filtering corresponds to a multiplication of the distance of the predetermined point and the operating point with a predetermined value between zero and one. Method according to one of the preceding claims, characterized in that the characteristic is a straight line or a non-linear function in two-dimensional space, a plane or curved surface in three-dimensional space or a surface in n-dimensional space. A method according to claim 17, characterized in that the two-dimensional space is spanned by a drive quantity and a value corresponding to the capacity of the clutch. A method according to claim 17, characterized in that the three-dimensional space is spanned by a drive quantity and a value corresponding to the capacity of the clutch and a further variable on which the clutch capacity depends. A method according to claim 17, characterized in that the n-dimensional space is spanned by a drive quantity and a value corresponding to the capacity of the clutch and n - 2 other quantities on which the clutch capacity depends. Method according to one of the preceding claims, characterized in that the clutch control is a hydraulic system. Method according to one of the preceding claims, characterized in that the drive variable is a current I of the clutch control. Method according to one of the preceding claims, characterized in that the value corresponding to a clutch capacity is a clutch pressure p. A method according to claim 23, characterized in that a predetermined minimum value is 0 bar and a predetermined maximum value is 10 bar. A method according to claim 23 or 24, characterized in that the coupling pressure p is divided into areas. A method according to claim 25, characterized in that a first range of clutch pressures less than 3.0 bar, a second range of clutch pressures of 3.0 bar <= p <4.5 bar, a third range of clutch pressures of 4.5 <= p <6 , 0 bar and en fourth range clutch pressures greater than or equal to 6.0 bar. Method according to one of the preceding claims, characterized in that the values corresponding to a clutch capacity additionally comprise a value which corresponds to a pressure change in the clutch over time. Method according to one of the preceding claims, characterized in that the further sizes on which the coupling capacity depends, comprise a temperature value. Method according to one of the preceding claims, characterized in that the values corresponding to a clutch capacity additionally comprise an aging value of the clutch. Method according to one of the preceding claims, characterized in that the adaptation in step (c) takes place by means of linear regression or according to the Gaussian least squares method. Method according to one of the preceding claims, characterized in that the value corresponding to a clutch capacity is an output signal of a torque sensor. A method according to claim 31, characterized in that the output signal is a pressure signal. Method according to one of the preceding claims, characterized in that at least one predetermined fixed point of the characteristic function is recorded. A method according to claim 33, characterized in that the predetermined fixed point is a range centroid or a point of the characteristic at maximum or minimum drive magnitude or a point of the characteristic at maximum or minimum of a clutch capacity corresponding value. Method according to one of the preceding claims, characterized in that different sources for the clutch capacity corresponding value are used for different areas of the characteristic. Method according to one of the preceding claims, characterized in that the value corresponding to a clutch capacity is determined from a motor torque value at the clutch operated at the boundary between adhesion and slip or at low slip. Method according to one of the preceding claims, characterized in that the method is used for controlling an electronically controlled clutch. A method according to claim 37, characterized in that the method is used for controlling an electronically controlled clutch of a motor vehicle.

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