DE102008051295A1 - Hybrid drivetrain i.e. parallel hybrid drivetrain, controlling method for vehicle, involves controlling torque-fluctuation-free and speed fluctuation-free transition from electromotive drive operation to internal combustion engine operation - Google Patents

Abstract

The method involves controlling torque-fluctuation-free and speed fluctuation-free transition from an electromotive drive operation to an internal combustion engine operation. Torque (Mem) of an electric motor is increased linearly by an amount that corresponds to amount of dragging torque of the engine, where the torque of the motor is increased till auto restarting of the engine. The torque of the motor is reduced when the torque is smaller than the dragging torque of the engine, where the torque of the motor is reduced till auto restarting of the engine. An independent claim is also included for a parallel hybrid drive train comprising an electric motor.

Description

The The invention relates to a method for controlling a hybrid drive train, an electric motor, an internal combustion engine and at least one arranged between the electric motor and the engine clutch includes, wherein the internal combustion engine during an electromotive Ride is started. The invention further relates to a parallel Hybrid powertrain with at least one electric motor, one over a clutch with the electric motor connectable combustion engine and with a control unit for controlling the hybrid drive train.

From the DE 10 2007 052 737 A1 For example, a method for starting a hybrid powertrain and a hybrid powertrain are known, wherein the hybrid powertrain has at least one electric motor and at least one connected via a clutch with the electric motor internal combustion engine. In this case, the electric motor is driven with a first torque and with a generation of a start signal by means of a control unit, a closing operation of the clutch is started, during which closing the torque of the electric motor is increased. A generated due to this increase additional torque of the electric motor is transmitted by means of the clutch to the engine, wherein a drive speed of the engine approaches a drive speed of the electric motor. After reaching a predetermined speed of the internal combustion engine, the torque of the electric motor is reduced such that it corresponds to a sum of a desired drive torque and a drag torque of the internal combustion engine and keeps the internal combustion engine at the achieved speed. Furthermore, the internal combustion engine is ignited or started after reaching the predetermined speed, with the start of a self-running of the internal combustion engine, the torque of the electric motor is reduced by the drag torque and increases the torque of the engine and synchronously reduced to this increase the torque of the electric motor.

Of the Invention is based on the object, a relation to the Prior art improved method for controlling a hybrid powertrain and to provide a parallel hybrid powertrain, in particular an engagement of an internal combustion engine without noticeable speed and / or torque fluctuations even with electric motors with low Allow services.

Regarding of the method, the object is specified by the in claim 1 Characteristics and with regard to the parallel hybrid powertrain solved by the features specified in claim 10.

advantageous Embodiments of the invention are the subject of the dependent claims.

at the method of the invention for control a hybrid powertrain, an electric motor, an internal combustion engine and at least one between the electric motor and the internal combustion engine arranged clutch, the internal combustion engine is during started an electromotive drive. According to the invention a torque fluctuation-free and speed fluctuation-free transition from the electromotive drive to an engine operation or a combined operation controlled. Thus, the transition for occupants of a vehicle not noticeable what leads to a high driving comfort. Continue to be due the torque fluctuation-free and speed fluctuation-free transition Vibrations in the hybrid powertrain reduced, resulting in a reduction Wear of the hybrid powertrain results.

To the Achieving the torque fluctuation-free and speed fluctuation-free transition is preferably at a time of generation of a start signal for the internal combustion engine through the control unit the clutch closed and meanwhile a torque of the electric motor continuous, in particular linear or approximately linear, increased by an amount equal to the amount of a drag torque of the internal combustion engine corresponds to its self-starting.

is the free available torque of the electric motor lower as the drag torque of the internal combustion engine until its self-starting, is a proportion of the torque of the electric motor, which as the drive torque is used, reduced, so that always sufficient torque to drive or for towing the internal combustion engine available stands.

alternative or in addition to closing the clutch to Time of generation of a start signal becomes the internal combustion engine by means of a starter until reaching a maximum speed driven by the starter. Thus, the invention Process and its embodiments in a profitable manner also applicable when the electric motor used has a low power having.

According to an advantageous development, the clutch is closed upon reaching a certain, in particular the maximum speed of the starter and while a torque of the electric motor continuously, in particular linear or approximately linearly increased by an amount corresponding to the amount of a drag torque of the internal combustion engine to its self-starting.

there This is done by closing the clutch by the amount the drag torque of the engine increased, additional Torque of the electric motor transmitted to the internal combustion engine.

Around a torque fluctuation-free and speed fluctuation-free transition from the electromotive drive to an engine operation or to produce a combined operation will be achieved upon a start speed of the engine, the clutch reopened and the internal combustion engine started, during opening the clutch torque of the electric motor by the amount of Drag torque of the engine is reduced.

According to one Embodiment of the method according to the invention After the engine has started, its speed will increase increases a target speed, which a speed of the electric motor or a transmission input speed, so that one on it following closing the clutch can be done without jerk.

at Reaching the target speed is next to the closing of the Clutch then the torque of the internal combustion engine increased to a setpoint and synchronous to the torque of the Electric motor reduced, resulting in a for the vehicle occupants no noticeable change in internal combustion engine operation or the combined operation results.

Of the Parallel hybrid powertrain according to the invention includes at least one electric motor, one via a Clutch with the electric motor connectable combustion engine and a control unit for controlling the hybrid powertrain, wherein the Control unit means for carrying out the inventive Having method and its developments. With the means these are, in particular, sensors which, for example, as torque sensors for detecting torques of the internal combustion engine, the electric motor and the coupling are formed. Furthermore include the means speed sensors, which at least rotational speeds of the internal combustion engine and the electric motor capture.

According to one particularly advantageous embodiment of the invention is a starter provided by means of which the internal combustion engine until reaching a maximum speed of the starter is driven, so that the Combustion engine, even with low-power electric motors speed fluctuation-free and torque fluctuation freely switchable or activatable. to Detecting the rotational speeds of the starter is again preferably at least a speed sensor is provided, which is part of the control unit is.

In various developments of the parallel hybrid powertrain is the clutch as a friction clutch, especially as a wet friction clutch or formed as a dry friction clutch.

embodiments The invention will be described in more detail below with reference to drawings explained.

there demonstrate:

1 FIG. 2 schematically shows a torque curve of an electric motor, an internal combustion engine and a clutch during a transition from an electromotive drive to an internal combustion engine operation, FIG.

2 schematically the torque curve of the clutch according to 1 and a speed curve of the electric motor and the internal combustion engine during the transition from an electromotive drive to the engine operation,

3 schematically a torque curve of an electric motor, an internal combustion engine and a clutch at a transition from an electromotive drive to an internal combustion engine operation, wherein the electric motor is supported by a starter, and

4 schematically the torque curve of the clutch according to 2 and a speed curve of the electric motor and the internal combustion engine in the transition from an electromotive drive to the engine operation, wherein the electric motor is supported by a starter.

each other corresponding parts are in all figures with the same reference numerals Mistake.

1 FIG. 4 illustrates a torque curve M of an electric motor, an internal combustion engine and a clutch at a transition from an electromotive drive to an engine operation as a function of the time t. 2 represents the course of the torque M _{K of} the clutch and a speed curve n of the electric motor and the internal combustion engine at the transition from the electromotive drive to internal combustion engine operation. The electric motor, the internal combustion engine and arranged between the electric motor and the internal combustion engine clutch form a parallel hybrid drive not shown strand, in particular a vehicle, wherein the internal combustion engine is started during an electromotive drive. In the following, both the method according to the invention, the parallel hybrid powertrain according to the invention and developments thereof will be described with reference to both 1 and 2 explained in more detail.

The transition from the electromotive drive to a combustion engine operation takes place in particular when a power of the electric motor alone is insufficient to drive the vehicle or an energy reserve of an electrical energy source of the electric motor, for example an accumulator, is used up. In order to achieve a torque fluctuation-free and speed fluctuation-free transition from the electromotive drive to the engine operation, the clutch is closed at a first time t ₁ of generating a start signal for the internal combustion engine by means of a control unit, not shown, and while a torque M _{EM of} the electric motor continuously, in the illustrated embodiment linearly increased.

The torque M _{EM of} the electric motor is thereby increased up to the second time t ₂ by the same amount, which due to a drag torque, ie a negative torque M _VM , the internal combustion engine via the clutch, ie the torque M _{K of} the clutch transmitted to the electric motor becomes.

The clutch remains closed until the internal combustion engine has reached a starting rotational speed n _start at time t ₃ , in which a self- _{running of} the internal combustion engine is possible by igniting a fuel mixture.

From the time t ₃ until reaching the time t ₄ , in which the clutch is fully opened again, the torque M _{EM of} the electric motor is reduced by the torque M _{K of} the clutch.

At the same time, the rotational speed n _{VM of} the internal combustion engine is increased until a rotational speed n _{EM of} the electric motor is reached at a _nominal rotational speed n _VMSoll , wherein when this _nominal rotational speed n _{VMSoll is reached,} the clutch is closed at time t ₅ and thus the torque M _{K thereof is} increased. Since the speed n _{VM of} the internal combustion engine at this time t ₅ equal to the speed n _{EM of} the electric motor, it comes at the full engagement of the engine in the parallel hybrid powertrain to no drag torque and thus to a speed fluctuation-free and torque fluctuation-free engagement of the engine.

For the transition into internal combustion engine operation, which is completely reached at time t ₇ , the torque M _{VM of} the internal combustion engine is increased from time t ₆ and at the same time the torque M _{EM of} the electric motor is reduced by the same amount, ie synchronously.

The 3 and 4 show on the basis of a torque curve M of the electric motor, the internal combustion engine and the clutch or the curve of the torque M _{K of} the clutch and the speed curve n of the electric motor and the internal combustion engine in the transition from an electromotive drive to the engine operation, an advantageous embodiment of the invention, in which the Electric motor is assisted when engaging the internal combustion engine of a starter.

The support is used in particular when the rotational speed n _{EM of} the electric motor is low or a freely available torque of the electric motor is too low to compensate for the drag torque of the internal combustion engine transmitted by the torque M _{K of} the clutch to the electric motor.

In this case, the starter is activated at a time t _{1 of} the generation of the starting signal of the internal combustion engine and the internal combustion engine until reaching a maximum speed n _StMax the starter driven at time t ₁ and upon reaching this maximum speed n _StMax the clutch is closed.

Subsequently, at the times t ₁ to t ₇ in the 1 and 2 described method to ensure the torque fluctuation-free and speed fluctuation-free transition to engine operation.

alternative for pure engine operation or electric motor operation is from a not shown combined operation the combustion and the electric motor possible.

M

torque curve

M _EM

torque

M _K

torque

M _VM

torque

_EM

rotation speed

n _VM

rotation speed

n _VMSoll

Target speed

n _start

Starting speed

n _StMax

rotation speed

t

Time

t ₁ to t ₇

time

t ₁

time

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 102007052737 A1 [0002]

Claims (14)

A method of controlling a hybrid powertrain comprising an electric motor, an internal combustion engine and at least one clutch disposed between the electric motor and the internal combustion engine, wherein the internal combustion engine is started during an electromotive drive, characterized in that a torque fluctuation-free and speed fluctuation-free transition from the electromotive drive to an engine operation or a combined operation is controlled. A method according to claim 1, characterized in that at a time (t ₁ ) generating a start signal for the internal combustion engine by a control unit, the clutch closed while a torque (M _EM ) of the electric motor continuously, in particular linearly or approximately linearly increased by an amount is equal to the amount of a drag torque of the internal combustion engine until its self-starting. A method according to claim 2, characterized in that a proportion of the torque (M _EM ) of the electric motor, which is used as a drive torque, is then reduced when the free available torque of the electric motor is less than the drag torque of the internal combustion engine to its self-starting. A method according to claim 1, characterized in that at a time (t ₁ ) of generating a start signal, the internal combustion engine is driven by a starter until reaching a maximum speed (n _StMax ) of the starter. A method according to claim 4, characterized in that upon reaching a certain, in particular the maximum speed (n _StMax ) of the starter clutch closed and while a torque (M _EM ) of the electric motor is continuously, in particular linearly or approximately linearly increased by an amount , which corresponds to the amount of a drag torque of the internal combustion engine to its self-starting. Method according to one of the preceding claims, characterized in that by closing the clutch that increased by the amount of drag torque of the internal combustion engine, transmit additional torque of the electric motor to the internal combustion engine becomes. Method according to one of the preceding claims, characterized in that upon reaching a starting speed (n _start ) of the internal combustion engine, the clutch re-opened and the internal combustion engine is started, wherein during the opening of the clutch, the torque (M _EM ) of the electric motor by the amount of the drag torque of the internal combustion engine is reduced. Method according to one of the preceding claims, characterized in that after starting the internal combustion engine whose speed (n _VM ) is increased to a desired speed (n _VMSoll ), which corresponds to a speed (n _EM ) of the electric motor or a transmission _input speed. A method according to claim 8, characterized in that upon reaching the target speed (n _VMSoll ), the clutch is closed again, then the torque (M _VM ) of the engine is increased to a desired value and synchronously to the torque (M _EM ) of the electric motor is reduced. Parallel hybrid powertrain with at least one Electric motor, one via a coupling with the electric motor connectable internal combustion engine and with a control unit for controlling the hybrid drive train, characterized in that the control unit Means for carrying out the method according to one of the claims 1 to 9. Parallel hybrid drive train according to claim 10, characterized in that a starter is provided, by means of which the internal combustion engine is driven until reaching a maximum speed (n _StMax ) of the starter. Parallel hybrid powertrain according to claim 10, characterized in that the coupling is designed as a friction clutch is. Parallel hybrid powertrain according to claim 10, characterized in that the clutch as a wet friction clutch is trained. Parallel hybrid powertrain according to claim 10, characterized in that the clutch as a dry friction clutch is trained.