KR102532027B1 - How to determine the engagement point of the hybrid clutch of a hybrid vehicle - Google Patents

Abstract

The present invention relates to a method for determining the bite point of a hybrid clutch of a hybrid vehicle, wherein the hybrid clutch (4) separates or connects an internal combustion engine (2) and an electric motor (3), and the hybrid vehicle During operation of the gripping point (TP) is adapted. In one method in which misadaptation of the gripping point and automatic readjustment of the hybrid clutch can be distinguished from each other, after the gripping point adaptation, the validity of the gripping point (TP _n ) determined during the gripping point adaptation is checked by a statistical method before being used again. do.

Description

How to determine the engagement point of the hybrid clutch of a hybrid vehicle

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

DE 10 2010 024 941 A1 discloses a method for controlling a dual clutch transmission having two or more partial drive trains, each of which can be connected to an internal combustion engine by means of a clutch. During driving of a vehicle including a dual clutch transmission, an engagement point of a clutch is determined regardless of an engine torque of an internal combustion engine. The bite point is determined during vehicle start-up and adapted during vehicle operation.

In a hybrid vehicle with a hybrid drive train, the driving resistance can be overcome by conversion into mechanical energy from two independent energy sources, such as the fuel of the internal combustion engine and the electric energy of the traction battery of the electric motor. From DE 10 2008 030 473 A1 a method for determining the engagement point of an automated hybrid clutch in a hybrid drive train is known. The engagement point of the hybrid clutch disposed between the internal combustion engine and the electric motor is determined by analyzing the effect of the hybrid clutch gradually closing in the stopped internal combustion engine and the electric machine of the electric motor rotating at a preset number of revolutions. do. The hybrid clutch enables purely electric driving of the hybrid vehicle in the open state, while in the closed state allows torque from the internal combustion engine to be transmitted to the drive wheels.

Another function of the hybrid clutch is to start the internal combustion engine. To this end, by increasing the torque of the electric motor as much as desired and closing the hybrid clutch, energy is transferred to the stopped internal combustion engine to accelerate the internal combustion engine. In this case, since the torque of the electric motor is transmitted to the drive wheels at the same time, it is necessary to know exactly the torque transmitted by the hybrid clutch in order to prevent unwanted vehicle acceleration from the point of view of driving comfort.

The pinch point is a sample point of the clutch characteristic curve (clutch torque as a function of travel of the hybrid clutch). The reason why the gripping point needs to be adapted during operation of the hybrid vehicle is that the behavior of the clutch fluctuates. This fluctuating clutch behavior occurs in particular during automatic readjustment of the clutch due to detection of clutch wear.

In the case of self-regulating hybrid clutches, very rapid fluctuations in the clutch characteristic curve occur when automatic readjustment is carried out in the mechanism used. In order to attenuate this error, in the known method, the presently detected pinch point is not entirely dedicated to the clutch characteristic curve, but only a specific part. In this case, the previous bite points are weighted strongly, and the newly determined bite points are weighted only slightly. As a result, the error between the torque requested from the clutch and the set torque increases.

An object of the present invention is to provide a method for determining an engagement point in which an error between a torque requested and a set torque in a hybrid clutch is reduced.

According to the present invention, the above problem is solved by checking the validity of the nip points determined during the nip point adaptation by a statistical method before they are used again after the nip point adaptation. The plausibility check considers statistical methods. The specificity of this scheme is its responsiveness to fluctuations with distinctly different time constants, and avoidance of recognition and application of misdetermined pinch points due to misadaptation. Such misadaptation may be caused by errors in signal transmission or mismanipulation of the higher driving strategies. As a result, the accuracy of the bite point is improved when the clutch characteristic curve changes rapidly, which may occur when the clutch characteristic curve is automatically readjusted. Thereby, by means of the software, it can be distinguished whether the gripping point variation is due to misadaptation of the gripping point or due to the automatic readjustment of the hybrid clutch.

In one embodiment, a statistical variance is calculated from a predetermined number of grip points determined during adaptation of the plurality of grip points, and automatic readjustment of the hybrid clutch is estimated based on the calculated statistical variance when there are plausible-looking grip points; A new pinch point is set. The cause of the displacement of the gripping point of the hybrid clutch can be easily identified using the statistical distribution, and based on this, it can be determined whether readjustment of the gripping point is really necessary.

In one embodiment, the calculated statistical variance is compared to a variance threshold, wherein misadaptation of the grip point is estimated if the variance threshold is exceeded, and automatic readjustment of the hybrid clutch is estimated if the variance threshold is not met. It is statistically very frequent for the pinch point to fluctuate slightly relative to the previously determined pinch point. Through statistical analysis, the pinch point approaches the actual physical value in several adaptations. A distinction is made between rapid mechanical fluctuations and misadaptation of the engagement point due to automatic readjustment of the hybrid clutch, without the need to consider a compromise with the appropriately limited application of minute and very slow fluctuations in the mechanical dynamics, without the need to consider the performance of the driven hybrid clutch at any given time. Accuracy of torque capacity is guaranteed.

In one embodiment, when an automatic readjustment of the hybrid clutch is detected, the newly set engagement point is determined from an average value of a previously determined, preset number of engagement points. A reliable detection of the automatic readjustment of the hybrid clutch is ensured, so that an exact engagement point is always set for future operation of the hybrid vehicle.

In one variant, if misadaptation of the nip point is detected, the nap point established prior to the last nip point adaptation is maintained. Thereby, an erroneously determined bite point is discarded, and an obstacle in the operating progress of the hybrid vehicle is prevented.

In one alternative, if misadaptation of the nip points is detected, the nip points closest to the average value among the preset number of nip points are determined and set as new nip points. This makes it possible to set the engagement point smoothly due to the current operating state of the hybrid clutch.

In yet another alternative, if maladaptation of a nip point is detected, the nip point having the largest statistical error among at least a preset number of nip points is determined and is not taken into account when determining the statistical variance. In this way, erroneously determined pinch point values are not taken into account during adaptation. If the variance value can be reduced in the new calculation, the calculated average value of the remaining pinch point values is used as the new pinch point.

In one variant, after each nip point adaptation, the deviation between the nip point determined and other nip points that were determined in previous nip point adaptations is obtained, the deviation is compared to a nip point deviation threshold, and the deviation is nipped. Statistical variance is calculated only when the point deviation threshold is exceeded. This pinch point threshold comparison tells whether a larger pinch point variation is present. Statistical methods require a lot of computational time and are therefore only performed when large pinch point variations are estimated.

In one refinement, the engagement point in the adaptation of the engagement point is determined by slow operation of the hybrid clutch starting from the open position of the hybrid clutch to the closed state when a predetermined increase in torque is detected under observation of the torque of the electric motor. Since it is assumed that the internal combustion engine is in an inoperative state and only the electric motor is running during this bite point adaptation, the bite point is estimated based on the torque increase, and the torque of the electric motor is transmitted to the internal combustion engine at this point.

In one embodiment, pinch point adaptation is repeated periodically. The reason why such periodic repetition is necessary is to respond to fluctuating clutch behavior during operation of the hybrid vehicle.

The present invention allows for numerous embodiments. One of them will be described in more detail based on the accompanying drawings.

1 is a principle diagram of a hybrid drive.
2 is an embodiment of a method according to the present invention.

1 shows a principle diagram of a drive train 1 of a hybrid vehicle. The drive train includes an internal combustion engine (2) and an electric motor (3). A hybrid clutch 4 is disposed immediately after the internal combustion engine 2 between the internal combustion engine 2 and the electric motor 3 . The internal combustion engine (2) and the hybrid 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 clutch 4 is connected to a transmission 9 , which is disposed between the electric motor 3 and the transmission 9 and is a clutch element not shown in detail, for example a second clutch or torque converter. includes Transmission 9 transmits torque generated by internal combustion engine 2 and/or electric motor 3 to drive wheels 10 of the hybrid vehicle. At this time, the hybrid clutch 4 and the transmission 9 form a transmission system 11, which is driven by a clutch actuator 12, for example, a hydrostatic clutch actuator.

When the internal combustion engine 2 is restarted by the electric motor 3, sufficient torque is provided to the electric motor 3 to actually start the internal combustion engine 2 while driving the hybrid vehicle through the drive wheels 10 without loss of comfort. Accurate information of the clutch characteristic curve of the hybrid clutch 4 in which the clutch torque generated over the travel of the hybrid clutch 4 is reproduced is necessary to ensure that the point provided by the hybrid clutch 4 is reproduced. The contact point of the clutch characteristic curve is the engagement point TP, which means a position of the hybrid clutch 4 where the friction surfaces of the input or output parts of the hybrid clutch 4 come into frictional contact with each other.

The engagement point TP is very important in controlling the hybrid clutch 4 . Determination of the bite point TP can be carried out, for example, when the internal combustion engine 2 is at rest. For determination of the engagement point TP, the clutch setting torque applied to the hybrid clutch 4 is increased until the driving torque that can be allocated to the clutch setting torque in the electric motor 3 can be detected. In this case, it is assumed that the hybrid clutch 4 is in an open state and then gradually closes under observation of the torque of the electric motor 3. At this time, the electric motor 3 has a stable rotational speed by being in the rotational speed control mode. The hybrid clutch 4 is closed until the frictional engagement surfaces of the input part and the output part of the hybrid clutch 4 come into frictional contact and the minimum torque is transmitted to the electric motor 3, which is the minimum torque of the electric motor 3. detected through a corresponding reaction. The corresponding reaction is an increase in the predetermined torque by the motor 3 . The position of the hybrid clutch 4 where the predetermined torque increase occurs is referred to as an engagement point TP.

가 계산되어 물림점 임계값(S_TP)과 비교된다. 상기 차(

)가 물림점 임계값(S_TP)보다 작으면, 단계 120에서 제어에 기반하는 물림점(TP_n-1)이 하이브리드 클러치(4)의 추후 제어를 위해 유지된다. 그러나 상기 차(

)가 물림점 임계값(S_TP)보다 크면, 결정된 물림점(TP_n)의 타당성 검증이 수행된다. 타당성 검증을 위해 통계적 방법이 이용되며, 이 경우 단계 130에서, 물림점 적응들에서 이미 결정된, 사전 설정된 개수의 물림점들(TP_n-m)의 평균값(M_TP)이 산출된다. 이어서 단계 140에서 상기 평균값(M_TP)에 대한 개별 물림점들(TP_n-m)의 분산(VAR(TP))이 결정된다.In this embodiment, the hybrid clutch 4 is formed as an automatically readjusting clutch, which means that the release travel of the hybrid clutch 4 is automatically varied when wear occurs. These fluctuations must be taken into account when controlling the hybrid clutch 4 to ensure reliable control. FIG. 2 shows an embodiment of the method according to the invention, where a statistical method is used to determine whether the grip point variation is related to a misadaptation of the grip point TP or to an automatic readjustment of the hybrid clutch 4 . It is confirmed whether To this end, in step 100 pinch point adaptation is performed. Subsequently, in step 110, the nip point (TP _n ) determined in the nip point adaptation is compared with the nip point (TP _n−1 ) determined in the immediately preceding nip point adaptation. Difference from the two pinch points,

is calculated and compared to the pinch point threshold (S _TP ). The difference (

) is less than the engagement point threshold value S _TP , then in step 120 the control-based engagement point TP _n-1 is maintained for later control of the hybrid clutch 4 . However, the difference (

) is greater than the bite point threshold value (S _TP ), validation of the determined bite point (TP _n ) is performed. A statistical method is used for validation, in which case, in step 130, an average value (M _TP ) of a preset number of nip points (TP _nm ), which is already determined in the nip point adaptations, is calculated. Then, in step 140 , the variance (VAR(TP)) of the individual pinch points (TP _nm ) with respect to the average value (M _TP ) is determined.

In step 150, the variance (VAR(TP)) is compared to a variance pinch point threshold (S _V ). If the variance (VAR(TP)) is smaller than the variance pinch point threshold value (S _V ), in step 160, among the pinch points (TP _{n -m} ) underlying the average value (M _TP ), the hybrid clutch 4 A new pinch point for control (TP _n ) is determined, which corresponds to _the mean value (M _TP ). In step 150, if it is confirmed that the variance (VAR(TP)) is greater than the variance nip point threshold (S _V ), it is assumed that the last nip point adaptation was erroneous. Then, the nipping point TP _n is discarded, and the existing nipping point TP _n-1 continues to be used (block 170). However, if the variance (VAR(TP)) is smaller, that is to say the variance around the mean value (M _TP ) of the individual pinch points (TP _nm ) is small, the automatic readjustment of the hybrid clutch 4 due to wear is carried out. As a result, the new engagement point TP _n is used for later control of the hybrid clutch 4 .

In an alternative to block 170, a new pinch point (TP _{n +1 ) may be calculated instead of maintaining the previous pinch point (TP n-1} ) in case of misadaptation, where the average value (M _TP ) is The closest engagement point TP _nm is used as the new engagement point TP _n+1 , which will be the basis for the control of the hybrid clutch 4 (block 180). In another alternative (block 190), when misadaptation is confirmed, the nip point (TP _nm ) with the largest statistical error is excluded from the calculation, and the average value (M _TP ) of the remaining nip points (TP _n-m+1 ) is calculated. is calculated and used as the new pinch point (TP _new ).

After setting the nip point TP _n , a new nip point adaptation step is passed to determine additional nip points (block 100), and this process is repeated periodically.

The described solution describes a pinch point TP that can be quickly adapted with high reliability in the event of a large fluctuation of the characteristic curve of the hybrid clutch 4 and reduces the error due to the process at small deviations. With this process, it is possible to react to TP variations, in particular with distinctly different time constants.

1 drivetrain
2 internal combustion engine
3 electric motor
4 hybrid clutch
5 crankshaft
6 rotor
7 stator
8 output shaft
9 gearbox
10 driving wheel
11 transmission system
12 clutch actuator
TP pinch point
M _TP average value
VAR(TP) Dispersion
S _V Distributed Cleavage Threshold
S _TP pinch point deviation threshold

Claims (10)

A method for determining the engagement point of a hybrid clutch of a hybrid vehicle, wherein the hybrid clutch (4) separates or connects an internal combustion engine (2) and an electric motor (3), and the engagement point (TP) is adapted during operation of the hybrid vehicle. , In the method for determining the engagement point of the hybrid clutch of the hybrid vehicle,
After the bite point adaptation, the validity of the bite point (TP _n ) determined during the bite point adaptation is checked by a statistical method before being used again,
As a statistical method, a statistical variance (VAR(TP)) is calculated from a plurality of pinch points (TP _nm ) of a preset number determined at different bite point adaptations, and in the presence of a valid pinch point (TP _n ), the above A method for determining the engagement point of a hybrid clutch, characterized in that the automatic readjustment of the hybrid clutch (4) is estimated on the basis of the calculated statistical variance (VAR(TP)), and the engagement point (TP _n ) is continuously used. delete The method of claim 1, wherein the calculated statistical variance (VAR(TP)) is compared with a variance threshold (S _v ), and misfitting of the pinch point (TP _n ) is estimated when the variance threshold (S _v ) is exceeded. and the automatic readjustment of the hybrid clutch (4) is estimated when the dispersion threshold value (S _v ) is not reached. 4. The method according to claim 1 or 3, wherein, when automatic readjustment of the hybrid clutch (4) is detected, a newly set engagement point (TP) is calculated from an average value (M _TP ) of a previously determined, preset number of engagement points (TP _nm ). _n ) is determined. The method according to claim 1, characterized in that, when misadaptation of the engagement point (TP _n ) is detected, the engagement point (TP _n-1 ) set before adaptation of the engagement point (TP n) is maintained. The method according to claim 1, when misadaptation of the bite point (TP _n ) is detected, a new bite point (TP _new TP ) is determined by determining a bite point closest to an average value (M _TP ) among a preset number of bite points (TP _nm ). A method for determining a bite point of a hybrid clutch, characterized in that set to The method of claim 1, wherein, when misadaptation of the bite point (TP _n ) is detected, a bite point having the largest statistical error among at least a preset number of bite points (TP _nm ) is determined, and the statistical variance (VAR(TP)) is determined. A method for determining the bite point of a hybrid clutch, characterized in that it is not considered when determining 4. The method according to claim 1 or 3, wherein after each adaptation of the pinch point, the deviation between the determined pinch point (TP _n ) and another pinch point (TP _n-1 ) determined in the previous pinch point adaptation. (

) is obtained, the deviation is compared with the pinch point deviation threshold (S _TP ), and the deviation (

A method for determining the engagement point of a hybrid clutch, characterized in that the statistical variance (VAR(TP)) is calculated only when ) exceeds the engagement point deviation threshold (S _TP ). 4. The gripping point (TP _n ) of the hybrid clutch (4) according to any one of claims 1 or 3, when a predetermined torque increase is detected under observation of the torque of the electric motor (3) in the gripping point adaptation. A method for determining the engagement point of a hybrid clutch, characterized in that it is determined by slow actuation of the hybrid clutch (4) from an open position to a closed state. 4. The method according to any one of claims 1 to 3, characterized in that the engagement point adaptation is repeated periodically.

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