WO2013152846A1

WO2013152846A1 - Method for operating a hybrid drive device

Info

Publication number: WO2013152846A1
Application number: PCT/EP2013/001037
Authority: WO
Inventors: Georg Hommes
Original assignee: Audi Ag
Priority date: 2012-04-12
Filing date: 2013-04-09
Publication date: 2013-10-17
Also published as: DE102012007322A1

Abstract

The invention relates to a method for operating a hybrid drive device (1) of a motor vehicle having an internal combustion engine (2) and an electrical machine (6) as drive units, wherein a clutch (4) provided between the internal combustion engine (2) and electrical machine (6) for transferring a target effective torque is engaged by the electrical machine (6) in order to start the internal combustion engine (2), and wherein the rotational speed of the internal combustion engine (2) is detected while engaging the clutch (4). On the basis of a rotational speed gradient determined from the rotational speed, an actually transferred actual effective torque of the clutch (4) is determined and is compared to the target effective torque.

Description

Method for operating a hybrid drive device

The invention relates to a method for operating a hybrid drive device of a motor vehicle having an internal combustion engine and an electric machine as drive units, wherein for starting the internal combustion engine by the electric machine provided between an internal combustion engine and electric machine clutch for transmitting a desired effective torque is closed, wherein the speed of the internal combustion engine is detected when closing the clutch.

Methods of the type mentioned are known from the prior art. In hybrid drive devices with an internal combustion engine and an electric machine, the internal combustion engine can be driven by a torque of the electric machine from a standstill and start. The electric machine replaces the conventional starter in this respect. In particular, to start the internal combustion engine from the purely electrical operation of the motor vehicle, the coupling provided between the internal combustion engine and the electrical machine is closed, so that the torque generated by the electric machine is transmitted to the internal combustion engine for its driving. The clutch is closed or transmitted to transmit a desired torque. Usually, the desired effective torque is stored in the control unit as characteristic or characteristic as a function of the coupling position in order to be able to control the clutch to achieve the desired effective torque accordingly.

In the context of the present invention, the nominal effective torque is understood to mean an active torque which is stored, for example, in the control unit and which is assumed by the control unit as an active torque acting as a function of the current setting of the clutch.

For example, published patent application DE102006048358A1 discloses a method for controlling a hybrid drive, in which a desired value for a slip torque of the clutch is stored in a characteristic field. The slip torque corresponds in so far to the desired effective torque. Furthermore, the known method provides for adapting or correcting the setpoint effective torque in operation in order to achieve the fastest possible and reliable starting of the internal combustion engine. For this purpose, the speed of the internal combustion engine is monitored and the desired effective torque

CONFIRMATION COPY a higher value is incremented if the speed of the internal combustion engine is below a threshold within a predeterminable time interval. As a result, a slow approach to an optimal target effective torque is achieved.

The invention has for its object to provide a method by which the desired effective moment faster, especially without incrementing steps, can be adapted to the present actual moment of action.

The object underlying the invention is achieved in that, as a function of a rotational speed gradient determined from the rotational speed, an actually transmitted actual effective torque is determined and compared with the desired effective torque. From the speed gradient of the internal combustion engine when closing the clutch can be calculated, which torque is actually transmitted to the engine through the clutch. For this purpose, the driving torque counteracting forces of the internal combustion engine are expediently taken into account. By comparing the actually transmitted actual effective torque with the desired effective torque, the deviation from the desired effective torque can be detected in one step, without the need for several incrementing steps for this purpose.

Preferably, the desired effective torque is corrected or adapted as a function of the detected actual effective torque. In particular, by knowing the above-mentioned deviation, this can be made simple. The difference between the desired effective torque and the actual effective torque is preferably formed and the value of the desired effective torque stored in the control unit is supplemented by this difference. If the desired effective torque is stored in the form of a characteristic curve, it is preferable to calculate an actual effective torque characteristic curve when the clutch is closed, so that accordingly the entire

Nominal effective torque characteristic can be adjusted. For this purpose, a clutch position-dependent characteristic curve of the desired effective torque is preferably adapted or corrected as a function of the detected actual effective torque or the detected characteristic of the actual effective torque. A single starting operation of the internal combustion engine by closing the clutch thus suffices to quickly adapt the slip torque assumed by the control unit to the actual effective torque actually present.

Preferably, to determine the actual effective torque, a friction torque of the internal combustion engine, in particular a static friction torque of the internal combustion engine, with a moment of inertia of the combustion dependent on the speed gradient, is determined. motors added. The friction torque of the internal combustion engine is stored in the control unit preferably in the form of a characteristic curve or a characteristic field, in particular as a function of various operating parameters of the internal combustion engine, such as the operating temperature, the speed or the aging of the internal combustion engine. Furthermore, the inertia of the internal combustion engine is stored in the control unit or preferably multiplied by the rotational acceleration, from the speed gradient, in order to reproduce the inertia torque of the internal combustion engine. The friction torque and the inertia torque are essential to the torque of the electric machine counteracting forces that must be overcome by closing the clutch to turn the internal combustion engine or tearing. By knowing these values, it is thus possible to easily calculate the actual effective moment actually present.

According to an advantageous embodiment of the invention, a compression torque of the internal combustion engine is taken into account for determining the actual effective torque. The compression moment is to be understood as the moment which is generated by the air which is present in the cylinders of the internal combustion engine and which is to be compressed when it is turned on.

Particularly preferably, only the compression torque of the first-compressing cylinder of the internal combustion engine is taken into account. As the internal combustion engine continues to rotate beyond the first compression, the compression torque is not or only negligibly effective. In the further course, it can therefore be assumed that the torque requirement for the unfired rotation of the internal combustion engine is completely contained or taken into account in the friction torque. Preference is therefore given in the speed range of about 200 U / min until the firing of the internal combustion engine, or until the speed of the engine corresponds to the speed of the electric machine, assumed the following relationship: Actual effective torque = friction torque + inertial torque.

In the following, the invention will be explained in more detail with reference to the drawing. The only one shows

Figure a hybrid drive device in a simplified representation.

The figure shows in the simplified representation of a drive device 1 for a motor vehicle not shown here in detail. The drive device 1 has a combustion tion motor 2, on whose output shaft, a flywheel 3, in particular in the form of a two-mass flywheel is arranged. Furthermore, the output shaft is connected to a first coupling part of a clutch 4, which is designed in particular as a friction clutch. A second coupling part of the clutch 4 is connected to a transmission input shaft of a transmission 5. The transmission 5 is designed, for example, as a manual or automatic transmission and has, for example, a torque converter or a starting clutch. Between the gear 5 and the clutch 4 sitting on the transmission input shaft also an electric machine 6, which can be operated both motorized and regenerative, expediently their rotor rotationally fixed to the transmission input shaft and its stator are fixedly arranged on the drive device. The transmission has in the present embodiment, a further coupling point 7, through which the transmission with drive wheels 8 of the motor vehicle, or the hybrid drive device 1 is connected. The coupling point 7 may be, for example, a switching device of the transmission, for example in the form of positively co-operating gears, friction or jaw clutches. At the coupling point 7 can thus take place in the transmission 5 a frictional connection or interruption to the drive wheels. Furthermore, the hybrid drive device 1, a control unit 9, which is designed in particular as an engine control unit and signal technically connected to at least the internal combustion engine 2, the clutch 4 and the electric machine 6 to control these and to detect operating parameters of said components. In addition, the control unit 9 is also connected to a speed sensor 10 which is assigned to the internal combustion engine 2 and in particular its output shaft to detect the rotational speed of the internal combustion engine.

When carried out by means of the electric machine 6, unfired slip start the engine 2 is started from a standstill by the clutch 4 is operated or closed, so that their coupling parts engage each other in operative connection, in particular with each other in frictional operative connection. Depending on the engagement position or position of the clutch 4 or its coupling parts, this results in a transmitted or transmissible active torque via the clutch 4. In the control unit 9, depending on the position of the clutch 4, corresponding values for this moment of action are stored as desired effective moment. Depending on the set position of the clutch 4, the control unit 9 assumes that the corresponding desired effective torque is transmitted from the clutch 4. However, the actual transmitted torque of the clutch 4 may change in the same (on) position, in particular over the life of the clutch 4. In order for the burn tion motor 2 can always safely be started by the electric machine 6 without, for example, a jerking in the drive train when closing the clutch 4 is formed, it is important to know the actual actual torque transmitted, or to adjust the desired effective torque to the operation of the motor vehicle , Therefore, it is important to know exactly when starting the engine 2 and also when switching on the engine 2, if this is already running, the transmitted from the clutch 4 effective torque.

For this purpose, it is provided that a friction torque of the internal combustion engine 2 and an inertia torque of the internal combustion engine 2 are used as an indicator for the actually transmitted effective torque.

The friction torque of the internal combustion engine 2 is known for example from the engine test bench and stored in the control unit 9. In this case, the friction torque is stored, in particular as a static friction torque. It is also conceivable to deposit the friction torque as a function of operating parameters of the internal combustion engine, such as speed or operating temperature in maps.

The speed of the internal combustion engine 2 is - as mentioned - detected by means of the speed sensor 10. From the course of the speed, a speed gradient is formed and multiplied by the inertia of the internal combustion engine 2, which is also assumed to be known and stored in the control unit 9, in order to determine the inertia torque of the internal combustion engine 2.

Thus, in principle, the following formula results for determining the actually transmitted actual effective torque:

M, = M _R + J ^* dn / dt, where M | the actually transmitted actual effective torque, M _R corresponds to the friction torque of the internal combustion engine 2, J of the inertia of the internal combustion engine 2 and dn / dt the speed gradient.

In addition, in the present embodiment, a compression torque of the engine 2 is also considered. This is necessary to overcome the first compression of the first-compressing cylinder when driving the engine 2. The compression torque is after turning Beyond the first compression addition no longer effective, so that it can be assumed in the further course that the torque requirement for the unfired turning of the internal combustion engine 2 in the frictional torque M _{R is} completely contained. Thus, the above formula applies in particular for a speed range of the internal combustion engine 2 of about 200 U / min to the fired operation of the internal combustion engine 2 or until the rotational speeds of the electric machine 6 and the internal combustion engine 2 match.

The difference between the thus determined actual effective torque and the stored or assumed in the control unit 9 target effective torque shows the current characteristic error, wherein the nominal effective torque characteristic of the control unit is corrected accordingly until a match with the detected actual effective torque or with a corresponding course of the actual effective torque is present as the actual effective torque characteristic.

LIST OF REFERENCE NUMBERS

driving device

internal combustion engine

flywheel

clutch

transmission

electric machine

Positive connection

drive wheels

control unit

Speed sensor

Claims

PATEN TA NSPR CHE

1. A method for operating a hybrid drive device (1) of a motor vehicle having an internal combustion engine (2) and an electric machine (6) as drive units, wherein for starting the internal combustion engine (2) by the electric machine (6) between an internal combustion engine (2 ) and electrical machine (6) provided for the transmission of a desired active torque is closed, and wherein the rotational speed of the internal combustion engine (2) when closing the clutch (4) is detected, characterized in that in dependence on one of the rotational speed determined rotational speed gradient, an actually transmitted actual effective torque of the clutch (4) is determined and compared with the desired effective torque.

2. The method according to claim 1, characterized in that the desired effective torque is corrected or adapted in dependence on the detected actual effective torque.

3. The method according to any one of the preceding claims, characterized in that a coupling position-dependent characteristic of the desired effective torque in dependence of the detected actual effective torque or an actual effective torque characteristic is adapted.

4. The method according to any one of the preceding claims, characterized in that for determining the actual effective torque, a friction torque of the internal combustion engine (2) with a dependent of the speed gradient inertial torque of the internal combustion engine (2) is added.

5. The method according to any one of the preceding claims, characterized in that for determining the actual effective torque, a compression torque of the internal combustion engine (2) is taken into account.

6. The method according to any one of the preceding claims, characterized in that only the compression torque of the first-compressing cylinder of the internal combustion engine (2) is taken into account.