DE102016208035A1 - Method of controlling a disconnect clutch in a hybrid powertrain - Google Patents

Abstract

The invention relates to a method for controlling a between an internal combustion engine and an electric machine arranged by an actuator automatically operated disconnect clutch of a hybrid powertrain with the electric machine subsequently arranged transmission. In order to be able to establish a relationship between the clutch torque (MK) of the disconnect clutch via an actuation path of the actuator and to be able to adapt continuously and robustly, a torque (ME0) becomes smaller than when the gearbox is decoupled from the electric motor with the internal combustion engine and the disconnect clutch disconnected applied the compression torque of the internal combustion engine, the separating clutch of the actuator along an actuation path successively opened and associated with a speed change of the electric machine, a disengaging point (A) of the separating clutch a predetermined actuation path.

Description

The invention relates to a method for controlling a between an internal combustion engine and an electric machine arranged by an actuator automatically operated disconnect clutch of a hybrid powertrain with the electric machine subsequently arranged transmission.

Hybrid powertrains of a motor vehicle in which an internal combustion engine and an electric machine form a drive unit are well known. In this case, a separating clutch can be arranged between the internal combustion engine and the electric machine. Here, the electric machine is a drive wheels of the motor vehicle driving gear downstream, so that can be purely electric driven and recuperated at open disconnect clutch and optionally arranged between the electric machine and gearbox open startup clutch or a neutral position of the transmission without engaged gear, the internal combustion engine can be started by means of the electric machine can. The separating clutch is automatically controlled by a control unit. For this purpose, an actuator is provided which actuates the separating clutch along an actuating path from a closed to an open state and vice versa. In this case, each individual actuating travel point is assigned a clutch torque to be transmitted. Due to influencing parameters such as temperature, wear and operating time of the separating clutch, this assignment changes. Due to a determination of the relationship between actuation travel and transmissible clutch torque, the separation clutch can be calibrated and continuously adapted. For this purpose, a touch point of the separating clutch is determined in the separating clutch begins to transmit torque and applied to this touch point, a clutch characteristic of the transmittable clutch torque on the actuation path. The clutch characteristic itself can be continuously calibrated and adapted, for example, by determining a so-called coefficient of friction, which represents a slope of the characteristic curve. Since the actuation path is usually detected only by means of relatively measuring displacement sensors, a calibration of the displacement sensor is carried out by an actuator of the actuator to a stop, for example, with an open friction clutch and there determines a reference position, for example, by energizing the Aktors no locomotion of the actuator is detected. Due to blockages before the stop a wrong reference position can be set, so that is assumed by a wrong coordinate origin, and the disconnect is operated incorrectly, for example, is suppressed in the closed state of the clutch, so that, for example, in a clutch with force-adjusting device unnecessary Nachstellvorgänge be initiated ,

From the DE 10 2008 030 473 A1 a method is known for the detection of the impact point of an automated separating clutch in a generic hybrid drive train. Here, the electric machine is operated speed-controlled when the internal combustion engine, the separating clutch supplied by the actuator successively and evaluated on the electric machine, a signal response that is assigned to a starting clutch torque. This means, mutatis mutandis, that the actuator delivers the clutch until a torque of the electric machine is transmitted via the separating clutch to the internal combustion engine and countered by this, whereby an operating parameter of the electric machine is influenced. The speed of the electric machine must be kept in a narrow speed range, this is not the case, the Tastpunktermittlung is canceled and continued the operation of the motor vehicle with a previously determined touch point. The transmission of the motor vehicle is located during the Tastpunktermittlung in a neutral position when not engaged gear or an optional starting clutch between the electric machine and transmission is open.

The object of the invention is the development of a method for controlling a separating clutch in a generic drive train. In particular, an adaptation of the separating clutch should be safer and more frequently possible. In particular, the frequency of adaptations should be increased. In particular, the robustness of the adaptations should be increased.

The object is achieved by the method of claim 1. The claims dependent on the claim give advantageous embodiments of the method of claim 1 again.

The proposed method is used to control a between an internal combustion engine and an electric machine arranged, automatically actuated by an actuator, such as an electric actuator disconnect clutch of a hybrid powertrain with the electric machine subsequently arranged transmission. The separating clutch can be closed or opened during active operation of the actuator. The separating clutch may have a force-controlled or path-controlled adjusting device. For example, an adjustment process can be initiated with an actively closed disconnect clutch with force-adjusting device by overpressing the closed disconnect clutch.

A method is proposed in which a torque smaller than the compression torque of the internal combustion engine is applied when the transmission is decoupled from the electric machine, the internal combustion engine and the clutch disconnected, the clutch is successively opened by the actuator along an actuation path and at a speed change the electric machine is assigned a Auskuppelpunkt the separating clutch a predetermined actuation path.

In order to be able to detect a speed change significantly during the determination of the Auskuppelpunkts and at the same time to avoid a start of the internal combustion engine by overcoming the compression torque, it has proven to be advantageous to specify the torque provided by the electric machine within a predetermined torque range. For example, the applied torque can be greater than 5 Nm and less than 30 Nm.

It can be provided that the speed change introduced by the electric machine is attributed to the clutch torque at the disengaging point in the case of a speed change occurring, for example, as a result of a separating clutch sufficiently open during the determination of the disengaging point. This means that when a predetermined rotational speed of the electric machine is exceeded and the internal combustion engine depends on the operating state of the separating clutch, the clutch torque transmitted via the separating clutch is equated to the torque of the electric machine applied to the separating clutch. In this case, the predetermined speed can be provided in the smallest possible, yet significantly detectable range, for example a few revolutions per minute or only fractions of a revolution. It is understood that, for example, when using incremental angle sensors of the electric machine, only a few angular increments for detecting a slip of the separating clutch and thus of the disengaging point can be sufficient.

In the case of a desired detection of the touch point of the separating clutch, in which this begins to transmit moment, can be determined from the disengaging point by means of a predetermined correlation of the touch point of the separating clutch and the touch point a predetermined actuation path. In this case, the correlation can be determined, for example empirically, for example, based on hysteresis properties and the like of the separating clutch.

In order to avoid a backlash of the electric machine after the at least partial opening of the separating clutch during the determination of Auskuppelpunkts, the electric machine can be operated speed-controlled and torque-limited after determining the Auskuppelpunkts. For example, the electric machine can be switched off after exceeding a predetermined speed.

In order to decouple the transmission during the determination of the Auskuppelpunkts, the proposed method can be carried out at an existing starting clutch between the electric machine and transmission with the start clutch. Alternatively, the method can be performed with or without existing starting clutch in a neutral position of the transmission without gear engaged.

In order to avoid rolling away of the motor vehicle when desired standstill and not activated parking brake, when the determination of Auskuppelpunkts by opening the clutch rolling by means of the gear when engaged gear and in - if present - closed start-up effective compression torque held motor vehicle by, for example, automated activation the parking brake of the motor vehicle are kept.

In other words, the proposed method of determining the Auskuppelpunkts a separating clutch by means of the following method steps in not necessarily exhaustive list:
During commissioning of the motor vehicle, for example, in a new or resistance of the internal combustion engine, the disengaging point of the separating clutch is determined when opening the separating clutch. On the basis of a first approximation, the disengaging point of the separating clutch and the engaging point, such as the touch point of the separating clutch, can be considered to be interdependent.

• • Eine vorhandene Anfahrkupplung zwischen Elektromaschine und Getriebe ist geöffnet oder das Getriebe befindet sich in Neutralstellung, so dass die Ge schwindigkeit des Kraftfahrzeugs gleich Null ist oder das Kraftfahrzeug zugkraft frei ausrollt.
• • Die Trennkupplung ist im Anfangsstadium des Verfahrens geschlossen.
• • Die Brennkraftmaschine befindet sich im Stillstand.

The following boundary conditions apply:

• • An existing starting clutch between the electric machine and transmission is open or the transmission is in neutral position, so that the Ge speed of the motor vehicle is equal to zero or the motor vehicle traction rolls freely.
• • The disconnect clutch is closed at the initial stage of the process.
• • The internal combustion engine is at a standstill.

• 1. Die Elektromaschine bringt ein kleines Drehmoment auf und verspannt den Antriebsstrang, indem die Elektromaschine aufgrund des Drehmoments wegdrehen will, jedoch von der stillgesetzten Brennkraftmaschine daran gehindert wird. Das Drehmoment der Elektromaschine wird dabei so groß, beispielsweise größer 5 Nm eingestellt, dass im Verlauf des Verfahrens am Auskuppelpunkt ein deutlicher Drehzahlanstieg erfassbar ist. Das eingestellte Drehmoment wird kleiner als ein Startmoment der Brennkraftmaschine, beispielsweise kleiner 30 Nm eingestellt. Um nach dem Auskuppeln der Trennkupplung zu hohe Drehzahlen der Elektromaschine zu vermeiden, kann die Elektromaschine in Drehzahlregelung und gleichzeitiger Momentenbegrenzung betrieben werden.
• 2. Der Aktor zur Betätigung der Trennkupplung fährt langsam in Richtung „Kupplung öffnen“.
• 3. Am Ende der Kupplungskennlinie bei im Wesentlichen offenen Zustand der Trennkupplung liegt das Drehmoment der Elektromaschine oberhalb des Kupplungsmoments und führt dazu, dass die Drehzahl der Elektromaschine ansteigt. Der Auskuppelpunkt, an dem das Kupplungsmoment dem von der Elektromaschine aufgebrachten Drehmoment wie E-Motormoment entspricht, kann über die ansteigende Drehzahl der Elektromaschine ermittelt werden.
• 4. Das Drehmoment der Elektromaschine wird wieder reduziert.

The implementation of the disengaging point determination:

• 1. The electric machine applies a small torque and braces the drive train by the electric machine wants to turn away due to the torque, but of the Stopped internal combustion engine is prevented. The torque of the electric machine is so large, for example, set greater than 5 Nm, that in the course of the process at the disengaging a significant increase in speed can be detected. The set torque is set smaller than a starting torque of the internal combustion engine, for example, less than 30 Nm. To avoid too high rotational speeds of the electric machine after disengaging the clutch, the electric machine can be operated in speed control and simultaneous torque limiting.
• 2. The actuator for actuating the separating clutch moves slowly in the direction "open clutch".
• 3. At the end of the clutch characteristic at substantially open state of the clutch, the torque of the electric machine is above the clutch torque and causes the speed of the electric machine increases. The disengaging point at which the clutch torque corresponds to the torque applied by the electric motor, such as the E-motor torque, can be determined by the increasing speed of the electric machine.
• 4. The torque of the electric machine is reduced again.

• • Ein zu weites Öffnen der Trennkupplung und damit gegebenenfalls eine Schädigung oder im Extremfall eine Zerstörung der Kupplung kann rechtzeitig verhindert werden, da während des Öffnens durch die Ermittlung des Auskuppelpunkts zugleich der sofortige Zustand der geöffneten Trennkupplung erfasst wird und ein Anfahren des Anschlags zur Ermittlung der Referenzposition plausibilisiert erfolgen kann.
• • Die Ermittlung des Auskuppelpunkts kann bei jeder Inbetriebnahme des Kraftfahrzeugs durchgeführt werden. In üblicher Weise wird bei jeder Inbetriebnahme des Kraftfahrzeugs ausgehend von einer geschlossenen Trennkupplung diese geöffnet, so dass während dieses Auskuppelvorgangs der Auskuppelpunkt bestimmt werden kann. Demnach kann der Auskuppelpunkt in jedem Fall vor dem ersten Start der Brennkraftmaschine als bekannt vorausgesetzt werden.
• • Die Ermittlung des Auskuppelpunkts ist im Gegensatz zur bekannten Ermittlung eines Tastpunkts bei sich schließender Trennkupplung robuster, da auf jeden Fall ein Auskuppelpunkt zugeordnet werden kann. Die bisherige Tastpunktermittlung kann aus verschiedenen Gründen erfolglos verlaufen. Beispielsweise kann eine Erlaubnis zur Durchführung der Tastpunktermittlung frühzeitig aufgrund einer überlagerten Betriebsstrategie entzogen werden oder die Drehzahl der Elektromaschine nicht stabil innerhalb des definierten Drehzahlbands gehalten werden oder dergleichen.

The proposed method offers advantages in particular:

• • Too wide opening of the clutch and thus possibly damage or in extreme cases destruction of the clutch can be prevented in good time, since during opening by detecting the Auskuppelpunkts at the same time the immediate state of the opened separating clutch is detected and a start of the stop to determine the Reference position made plausible.
• • The determination of the disengaging point can be carried out each time the vehicle is put into service. In the usual way, each time the motor vehicle is started up, starting from a closed separating clutch, it is opened, so that the disengaging point can be determined during this disengaging operation. Accordingly, the disengaging point can in any case be assumed to be known before the first start of the internal combustion engine.
• • The determination of the disengaging point is, in contrast to the known determination of a touch point, more robust when the disconnect clutch is closing, as a disengaging point can always be assigned. The previous touch point determination can be unsuccessful for various reasons. For example, a permission to perform the Tangenpunktermittlung can be withdrawn early due to a superimposed operating strategy or the speed of the electric machine can not be kept stable within the defined speed range or the like.

The invention is based on the in the 1 and 2 illustrated embodiment illustrated. Showing:

1 a generic drive train for carrying out the method and

2 a diagram for the procedure of the method.

The 1 shows the drive train 1 to carry out the proposed method in a schematic view. The internal combustion engine 2 and the electric machine 3 are by means of automatically actuated by means of an actuator, not shown, separating clutch 4 separably connected. The electric machine 3 is the transmission 5 which the drive wheels 6 drives, downstream.

The actuator actuates the separating clutch 4 along an actuation path. In order to associate the actuating travel with the transmittable clutch torque, an adaptable clutch characteristic of the clutch torque via the actuating travel is provided, which is running, for example, before commissioning of the drive train 1 is adapted. For this purpose, at least one Auskuppelpunkt on an associated actuation path of the separating clutch 4 determined. The electric machine 3 is doing while stopped internal combustion engine 2 , closed disconnect clutch 4 and end open drive train, that is, in this embodiment in the neutral position of the transmission 5 energized when the gear is not engaged with a torque between 5 and 30 Nm. This torque is via the closed disconnect clutch 4 on the internal combustion engine 2 transferred and held against there by this. A change in the speed of the electric machine 3 therefore does not occur. Subsequently, the separating clutch 4 as long as slowly along the actuation path of the actuator, until the electric machine 3 a speed is detected. At this point, the disengaging point of the separating clutch is determined and assigned to the covered actuating travel.

The 2 shows with reference to the 1 the diagram 7 with the moment M and the rotational speed n over the time t for carrying out the determination of the disengaging point A of the separating clutch 4 , Here the graph shows 8th the clutch torque M _{K of} the clutch 4 , the graph 9 the torque M _{E of} the electric machine 3 and the graph 10 the speed n _{E of} the electric machine 3 over time t.

In phase I will be at the electric machine 3 a torque M _{E0 set} at a level between 5 Nm and 30 Nm. That over the separating clutch 4 transmissible maximum clutch torque M _K0 is in the closed state a multiple greater than the torque M _E0 , so that the torque M _E0 completely on the internal combustion engine 2 transferred and is held by this.

In phase II, the clutch torque M _K is slowly reduced by displacing an actuator of the actuator along the actuation path.

At the beginning of phase III, the clutch torque M _{K of} the clutch corresponds to the torque M _{E of} the electric machine 3 and the rotor of the electric machine 3 starts to turn. The Auskuppelpunkt A is reached and is assigned to the current actuation path of the actuator of the actuator.

In phase IV, the speed reaches n _{E of} the electric machine 3 a predetermined value and is switched off.

LIST OF REFERENCE NUMBERS

1

 powertrain

2

 Internal combustion engine

3

 electric machine

4

 separating clutch

5

 transmission

6

 drive wheel

7

 diagram

8th

 graph

9

 graph

10

 graph

A

 disengagement point

M

 moment

M _E

 Torque of the electric machine

M _E0

 applied torque of the electric machine

M _K

 clutch torque

M _K0

 maximum clutch torque

n

 rotation speed

n _E

 Speed electric machine

t

 Time

I

 phase

II

 phase

III

 phase

IV

 phase

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102008030473 A1 [0003]

Claims (10)

Method for controlling a between an internal combustion engine ( 2 ) and an electric machine ( 3 ), actuated by an actuator automatically actuated separating clutch ( 4 ) of a hybrid powertrain ( 1 ) with one of the electric machines ( 3 ) subsequently arranged transmission ( 5 ), characterized in that at opposite the electric machine ( 3 ) decoupled transmission ( 5 ), when the internal combustion engine ( 2 ) and closed disconnect clutch ( 4 ) of the electric machine ( 3 ) a torque (M _E0 ) smaller than the compression torque of the internal combustion engine ( 2 ) is applied, the separating clutch ( 4 ) is successively opened by the actuator along an actuation path and at a speed change of the electric machine ( 3 ) a disengaging point (A) of the separating clutch ( 4 ) is assigned to a predetermined actuation path. A method according to claim 1, characterized in that the applied torque (M _E ) is greater than 5 Nm and less than 30 Nm. A method according to claim 1 or 2, characterized in that at a speed change from the electric machine ( 3 ) applied torque (M _E0 ) is assigned to the clutch torque (M _K ) at the predetermined actuating travel at the disengaging point (A). Method according to one of claims 1 to 3, characterized in that from the disengaging point (A) by means of a predetermined correlation of the touch point of the separating clutch ( 4 ) is determined and the touch point is assigned a predetermined actuation path. Method according to one of claims 1 to 4, characterized in that the electric machine ( 3 ) with the separating clutch open ( 4 ) is speed-controlled and torque-limited operation. Method according to one of claims 1 to 5, characterized in that the electric machine ( 3 ) is switched off after exceeding a predetermined speed. Method according to one of claims 1 to 6, characterized in that after the determination of the Auskuppelpunkts (A), a reference position is determined. Method according to one of claims 1 to 7, characterized in that the method is carried out at an existing starting clutch between the electric machine and transmission with the starting clutch. Method according to one of claims 1 to 8, characterized in that the method in a neutral position of the transmission ( 5 ) is performed without engaged gear. Method according to one of claims 1 to 9, characterized in that before opening the separating clutch ( 4 ), the opening of a starting clutch and / or a shifting of the transmission ( 5 ) in a neutral position when not engaged gear when the parking brake is not activated, the parking brake is activated.

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