WO2016127982A1

WO2016127982A1 - Method for determining a bite point of a hybrid clutch in a hybrid vehicle

Info

Publication number: WO2016127982A1
Application number: PCT/DE2016/200022
Authority: WO
Inventors: Ralf Mannsperger; Markus Lienhard
Original assignee: Schaeffler Technologies AG & Co. KG
Priority date: 2015-02-11
Filing date: 2016-01-20
Publication date: 2016-08-18
Also published as: KR102532027B1; KR20170115549A; CN107208720A; CN107208720B; DE102016200689B4; DE102016200689A1; DE112016000714A5

Abstract

The invention relates to a method for determining a bite point of a hybrid clutch in a hybrid vehicle, wherein the hybrid clutch (4) disconnects or connects an internal combustion engine (2) and an electric motor (3), and a bite point (TP) is adapted during operation of the hybrid vehicle. In a method in which it is possible to differentiate between incorrect adaptation of the bite point and automatic re-adjustment of the hybrid clutch, after adaptation of the bite point the bite point (TP_n) which is determined during this bite point adaptation is checked for plausibility with a statistical method before it continues to be used.

Description

Method for determining a touch point of a Hybndtrennkupplung a

hybrid vehicle

The invention relates to a method for determining a touch point of a hybrid disconnect clutch of a hybrid vehicle, wherein the hybrid disconnect clutch separates or connects an internal combustion engine and an electric motor and a touch point is adapted during operation of the hybrid vehicle.

DE 10 2010 024 941 A1 discloses a method for controlling a Doppelkupp- ment gearbox with at least two sub-drive trains, each of which can be coupled by means of a clutch with an internal combustion engine. When driving the, the dual-clutch transmission comprehensive vehicle, a touch point of the clutch is determined independently of the engine torque of the internal combustion engine. This touch point is determined during commissioning of the vehicle and adapted during operation of the vehicle.

In a hybrid powertrain hybrid vehicle, drivability from two independent sources of energy, such as fuel from an internal combustion engine and electrical energy from a traction battery of an electric motor, may be overcome by conversion to mechanical energy. From DE 10 2008 030 473 A1, a method for the detection of the impact point of an automated hybrid disconnect clutch in a hybrid drive train is known. The touch point of the hybrid disconnect clutch, which is arranged between an internal combustion engine and an electric motor, is determined when the internal combustion engine is stopped by slowly closing the hybrid disconnect clutch and evaluating the influence of the closing hybrid disconnect clutch on an electric motor of the electric motor rotating at a predetermined speed becomes. This hybrid disconnect clutch allows a purely electric driving of the hybrid vehicle in the open state, while in the closed state, the torque of the internal combustion engine is guided to the drive wheel.

Another task of the hybrid disconnect clutch is to start the combustion engine. For this purpose, by selectively increasing the torque of the electric motor and closing the hybrid disconnect clutch energy is transmitted to the stationary engine and thus accelerated. Regarding the ride comfort In this case, the torque transmitted by the hybrid disconnect clutch must be known exactly in order to avoid unwanted vehicle accelerations, since the torque of the electric motor is simultaneously transmitted to the drive wheels.

The touch point represents a support point of a clutch characteristic (clutch torque as a function of a path of the hybrid disconnect clutch). An adaptation of the touch point during operation of the hybrid vehicle is necessary due to a changed clutch behavior. Such a changed clutch behavior occurs in particular in a self-adjusting clutch due to detected clutch wear. In a self-adjusting hybrid disconnect coupling, a particularly rapid change in the clutch characteristic curve is produced when the self-adjustment is carried out in the mechanism used. To dampen such errors, a currently detected tactile point is not taken over in full but only to a certain extent in a clutch characteristic by known methods. The old touch point is strongly weighted and the newly determined touch point only slightly. A big mistake between required and adjusted torque on the clutch is the result.

The invention has for its object to provide a method for determining a touch point, in which errors between the required and adjusted torque on the hybrid disconnect clutch can be reduced. According to the invention, the object is achieved in that, after a touch point adaptation of the determined during this Tastpunktadaption Tastpunkt is checked before its further use with a statistical method for plausibility. This plausibility check takes account of statistical procedures. The special feature of the solution is the ability to react to changes with significantly different time constants as well as the detection and avoidance of the application of incorrectly determined tactile points due to incorrect adaptations. Such erroneous adaptations can be caused by errors in the signal transmission or incorrect operation of the parent driving strategy. As a result, the accuracy of the touch point is improved with rapid changes in the clutch characteristic, as occurs in a self-adjustment of the clutch characteristic. Thus, it can be discriminated by software whether the touch point change is an incorrect adaptation of the touch point or a touch point change as a result of the self-adjustment of the hybrid disconnect clutch. In one embodiment, a statistical variance is determined from a predetermined number of tactile points determined during multiple touch point adaptations, wherein a self-adjustment of the hybrid disconnect clutch is concluded and a new touch point is set on the basis of the determined statistical variance in the presence of plausible sensing points. By means of this statistical variance, the cause of the adjustment of the touch point of the hybrid disconnect clutch can be easily determined, from which it can be determined whether a readjustment of the touch point is really necessary.

In one embodiment, the determined statistical variance is compared with a variance threshold value, wherein a self-adjustment of the hybrid disconnect coupling is concluded when the variance threshold value is exceeded due to an incorrect adaptation of the touch point and when the variance threshold value is undershot. Small changes of the touch points to the previously determined touch point are statistically very common. Due to the statistical evaluation, the touch point approaches the actual physical value in several adaptations. By distinguishing between the rapid mechanical change of the touch point due to the self-adjustment of the hybrid disconnect clutch and a misadaptation, the accuracy of the torque capacity of the controlled hybrid disconnect clutch is ensured at all times without having to compromise with the moderately limited application of small and very slow change of the mechanics.

In one embodiment, upon detection of the self-adjustment of the hybrid disconnect clutch, the newly set sensing point is determined from an average of the predetermined number of previously determined sensing points. Since a reliable determination of the self-adjustment of the hybrid disconnect clutch is ensured, thus always an accurate touch point for further operation of the hybrid vehicle is set.

In a variant, the detection of the misadaptation of the touch point of the set before the last Tastpunktadaption tactile point is maintained. Thus, the erroneously determined tactile point is discarded and interference in the course of operation of the hybrid vehicle is suppressed. In an alternative, upon detection of the misadaptation of the touch point from the predetermined number of touch points, the touch point with the shortest distance to the mean value is determined and set as a new touch point. Thus, a sliding tactile Point adjustment possible, which is due to the immediate operating state of the hybrid disconnect clutch.

In a further alternative, upon detection of the misadaptation of the touch point, at least one touch point with the largest statistical error from the predetermined number of touch points is determined, which is disregarded when determining the statistical variance. In this way incorrectly determined probe point values are not included in the calculation during the adaptation. If the value of the variance can be reduced on re-calculation, the calculated mean of the remaining touch-point values is used as the new touch-point. In a variant, after each touch point adaptation, a difference is formed between the determined touch point and another touch point, which was determined in the preceding touch point adaptation, which is compared with a touch point difference threshold value, wherein the statistical variance is only determined if the difference Touchpoint difference threshold exceeds. Such a tactile threshold comparison is an indication of whether a larger Tastpunktänderung has resulted. Since the statistical method requires a great deal of computation time, it is only executed if a large change in the tactile point is suspected.

In a further development, the touch point is determined by a slow actuation of the hybrid disconnect coupling, starting from an open position of the hybrid disconnect clutch in a closed state, under observation of a moment of the electric motor in the Tastpunktadaption, if a defined torque increase is detected. Since it is assumed that the internal combustion engine is at this Tastpunktadaption in the stationary state and only the electric motor moves, it is closed due to the torque increase to the touch point, since the torque is transmitted from the electric motor at this point to the engine.

In one embodiment, the touch point adaptation is repeated cyclically. This cyclic repetition is necessary to respond to the changed clutch behavior during operation of the hybrid vehicle. The invention allows numerous embodiments. One of them will be explained in more detail with reference to the figures shown in the drawing.

Show it: Fig. 1 is a Phnzipdarstellung a hybrid drive

Fig. 2 shows an embodiment of the method according to the invention.

In Fig. 1 is a schematic diagram of a drive train 1 of a hybrid vehicle is shown. This drive train comprises an internal combustion engine 2 and an electric motor 3. Between the internal combustion engine 2 and the electric motor 3, a hybrid separating clutch 4 is arranged directly behind the internal combustion engine 2. Internal combustion engine 2 and hybrid disconnect clutch 4 are connected to each other via a crankshaft 5. The electric motor 3 has a rotatable rotor 6 and a fixed stator 7. The output shaft 8 of the hybrid disconnect clutch 4 is connected to a transmission 9, which contains a coupling element (not further illustrated), for example a second clutch or a torque converter, which is arranged between the electric motor 3 and the transmission 9. The transmission 9 transmits the torque generated by the internal combustion engine 2 and / or the electric motor 3 to the drive wheels 10 of the hybrid vehicle. The hybrid separation clutch 4 and the transmission 9 thereby form a transmission system 1 1, which is controlled by a clutch actuator 12, for example by a hydrostatic clutch actuator.

To ensure that when the internal combustion engine 2 is restarted by the electric motor 3, sufficient torque is provided by the electric motor 3, which both moves the hybrid vehicle via the drive wheels 10 without loss of comfort and at the same time actually starts the engine 2, an accurate knowledge of a clutch characteristic is Hybrid disconnect clutch 4 is required, in which a clutch torque across the path of the hybrid disconnect clutch 4 is shown. An interface of this clutch characteristic is the touch point TP, by which the position of the hybrid disconnect clutch 4 is to be understood, in which the friction surfaces of the input or output part of the hybrid disconnect clutch (4) come into frictional contact with each other.

This touch point TP is of particular importance for the control of the hybrid disconnect clutch 4. The determination of the touch point TP can take place, for example, when the internal combustion engine 2 is shut down. To determine the touch point TP, a clutch desired torque applied to the hybrid disconnect clutch 4 is increased until a drive torque that can be assigned to the clutch desired torque can be detected at the electric motor 3. It is a prerequisite that the hybrid separation clutch 4 is in an open state and then slowly under observation of the Mo- mentes of the electric motor 3 is fed. The electric motor 3 is in a speed-controlled operation and thus has a stable speed. The hybrid disconnect clutch 4 is closed until the friction engagement surfaces of input and output part of the hybrid disconnect clutch 4 are in frictional contact and a minimum torque is transmitted to the electric motor 3, which is detected by a corresponding reaction of the electric motor 3. This corresponding reaction consists in that a defined torque increase is given by the electric motor 3. The position of the hybrid disconnect clutch 4, in which this defined torque increase occurs, is referred to as the touch point TP. The hybrid disconnect clutch 4 is designed in the present case as a self-adjusting clutch, which means that when wear occurs, the Ausrückweg the hybrid disconnect clutch 4 changes automatically. Such a change must be taken into account when controlling the hybrid disconnect clutch 4 in order to ensure reliable control. FIG. 2 shows an exemplary embodiment of the method according to the invention, where it is determined by means of a statistical method whether a touch point change is an incorrect adaptation of the touch point TP or a self-adjustment of the hybrid disconnect coupling 4. For this purpose, in step 100, a touch point adaptation is performed. 10 of the particular touch point adaptation in this touch point TP _n with a touch point TP is compared _n- i Subsequently, in step 1, which was determined in the immediately preceding touch point adaptation. From these two scanning points a difference | TPn - TPn-1 1 is formed, which is compared with a Tastpunktsch well value STP. If the difference | TPn - TPn-1 1 is smaller than the Tastpunktschwellwert STP, then the control underlying Tastpunkt TP _n- i for the further activation of the hybrid separation clutch 4 is maintained in step 120. But if the difference | TPn - TPn-1 1 is greater than the Tastpunktschwellwert STP, SO is a plausibility of the determined touch point TP _n made. For plausibility, a statistical method is used, wherein in step 130 an average value M _T p is determined from a predetermined number of touch points TP _nm already determined in touch point adaptations. Subsequently, in step 140, the variance VAR (TP) of the individual scanning points TP _{nm is set} to this mean value M _T p.

In step 150, the variance VAR (TP) is compared with a variational sample threshold Sv. If the variance VAR (TP) is smaller than the variational sample threshold value Sv, then in step 160 the sampling points T _nm , which form the mean value M _T p, are used. a new touch point TP _{n is determined} for the further activation of the hybrid disconnect clutch 4, the new touch point TP _n corresponding to the mean value M _T p. If it is determined in step 150 that the variance VAR (TP) is greater than the variational sample threshold Sv, then it is assumed that the last probe adaptation was erroneous. This touch point TP _n is then discarded and the existing touch point TP _n- i is further used (block 170). However, if the variance VAR (TP) is smaller, ie the scattering of the individual scanning points TP _nm about the mean value M _T p is small, it is assumed that a self-adjustment of the hybrid disconnect coupling 4 as a result of wear has taken place so that the new sensing point TP _n is used for the further control of the hybrid separation clutch 4.

In an alternative to block 170, instead of maintaining the old touch point TP _n- i instead of misadapting, a new touch point TP _{n +} i can be calculated by the touch point TP _nm , which is closest to the mean value M _T p, as the new touch point TP _n + i of the control of the hybrid disconnect clutch 4 is based (block 180). In a further alternative (block 190) is eliminated upon detection of a false adaptation of the touch point TP _nm with the greatest statistical error of the calculation and TP i calculates a mean value M _T p from the remaining remaining sampling points _nm +, which then _newly as the new touch point TP is used.

After setting the touch point TP _n , a new touch point adaptation is transferred (block 100) to determine a further touch point, which is repeated cyclically.

The illustrated solution describes a touch point TP, which can be quickly adapted to large changes in the characteristic of the hybrid disconnect clutch 4 with a high degree of safety and by means of which with small deviations procedural errors are reduced. With this method, it is possible in particular to respond to changes in the touch point TP with significantly different time constants. LIST OF REFERENCE NUMBERS

1 powertrain

2 internal combustion engine

3 electric motor

4 hybrid disconnect clutch

5 crankshaft

6 rotor

7 stator

8 output shaft

9 gears

10 drive wheels

1 1 transmission system

12 clutch actuator

TP tactile point

M _T p average

VAR (TP) variance

Sv variance sample threshold

STP Tastpunktdifferenzsch well worth

Claims

claims

Method for determining a touch point of a hybrid disconnect clutch of a hybrid vehicle, wherein the hybrid disconnect clutch (4) disconnects or connects an internal combustion engine (2) and an electric motor (3) and a touch point (TP) is adapted during operation of the hybrid vehicle, characterized in that after Tactile point adaptation of the determined during this Tastpunktadaption Tastpunkt (TP _n ) before its further use with a statistical method for plausibility is checked.

Method according to Claim 1, characterized in that a statistical variance (VAR (TP)) is determined as the statistical method from a predefined number of multiple touch points (TP _n - _m ) determined during different touch point adaptations, based on the statistical variance ( VAR (TP)) is closed in the presence of a plausible Tastpunktes (TP _n ) on a self-adjustment of the hybrid disconnect clutch (4) and the new touch point (TP _n ) is used.

Method according to claim 2, characterized in that the determined statistical variance (VAR (TP)) is compared with a variance threshold value (Sv), wherein if the variance threshold value (Sv) is exceeded, an incorrect adaptation of the touch point (TP _n ) and if the variance threshold value is undershot Variance threshold (Sv) on a self-adjustment of the hybrid disconnect clutch (4) is closed.

A method according to claim 2 or 3, characterized in that upon detection of the self-adjustment of the hybrid separation clutch (4) of the newly set touch point (TP _n ) from an average value (M _T p) of the predetermined number of previously determined tactile points (TP _nm ) is determined ,

A method according to claim 1 or 2, characterized in that upon detection of the maladaptation of the touch point (TP _n ) of the set before the Tastpunktadaption Tastpunkt (TP _n- i) is maintained.

A method according to claim 1 or 2, characterized in that upon detection of the misadaptation of the touch point (TP _n ) from the predetermined number of touch points (TP _nm ) of the touch point with the smallest distance to the average (M _T p) determined and as a new touch point (TP _new ) is set.

7. The method according to claim 1 or 2, characterized in that upon detection of the mismatch of the touch point (TP _n ) at least one touch point with the largest statistical error from the predetermined number of touch points (TP _n - _m ) is determined, which at the determination of the statistical variance (VAR (TP)) is disregarded.

8. The method according to at least one of the preceding claims, characterized in that after each Tastpunktadaption a difference (| TPn - TPn-1 1) between the determined touch point (T _n ) and another touch point (TP _n- i), which in the is formed, which is compared with a Tastpunktdifferenzsch well value (STP), wherein the statistical variance (VAR (TP)) is determined only if the difference (| TPn - TPn-1 1) the Tastpunktdifferenzschwellwert ( STP).

9. The method according to at least one of the preceding claims, characterized in that in the Tastpunktadaption the touch point (TP _n ) by a slow actuation of the hybrid disconnect clutch (4), starting from an open position of the hybrid disconnect clutch (4) in a closed state, under observation a moment of the electric motor (3) is determined when a defined torque increase is detected.

10. The method according to at least one of the preceding claims, characterized in that the Tastpunktadaption is repeated cyclically.