DE102018221881A1 - Method for operating a drive train of a hybrid vehicle - Google Patents

Abstract

Method for operating a drive train of a hybrid vehicle, which has a hybrid drive (1) with an internal combustion engine (2) and an electric machine (3), a transmission (5) connected between the hybrid drive (1) and an output (4), a starting clutch ( 20) and a service brake (18), with a transmission control (10) for controlling and / or regulating the transmission (5), with a hybrid control (11) for controlling and / or regulating the electrical machine (3), with a brake control (17) for controlling and / or regulating the service brake (18), and control system (8) for performing such a method.

Description

The invention relates to a method for operating a drive train of a hybrid vehicle. The invention further relates to a control system for a drive train of a hybrid vehicle, which is set up to carry out such a method.

From the DE 10 2012 204 475 A1 the basic structure of a control system of a hybrid vehicle is known. A hybrid vehicle has a hybrid drive with an internal combustion engine and an electrical machine. A separating clutch is connected between the internal combustion engine and the electrical machine. The operation of the internal combustion engine is controlled and / or regulated by a motor control and the operation of the electrical machine by a hybrid control. Furthermore, a hybrid vehicle has a transmission connected between the hybrid drive, namely the electrical machine thereof, and an output, the operation of the transmission being controlled and / or regulated by a transmission control. A service brake acts on the output, the operation of which is controlled and / or regulated by a brake control. After DE 10 2012 204 475 A1 The transmission control determines a dynamic variable on the basis of a driving situation and / or a driver type and / or a vehicle type, on the basis of which the transmission control controls and / or regulates the execution of gearshifts in the transmission. The transmission control provides the dynamic variable of the hybrid control and possibly the brake control, in order to then control and / or regulate the operation of the electrical machine and, if appropriate, the operation of the service brake.

Then, if a braking torque is requested for a hybrid vehicle, for example by driver actuation of a brake pedal, this braking torque can be provided both by the electric machine of the hybrid drive in the recuperation mode thereof and via the service brake on the output. In order to operate the hybrid vehicle as efficiently as possible, there is a need to provide as much braking torque as possible through the recuperation operation of the electrical machine, in order to thereby charge an electrical energy store of the hybrid vehicle.

If the hybrid vehicle decelerates when braking, the speed at the input of the transmission drops, which makes it necessary to open a starting clutch of the hybrid vehicle in order to decouple the hybrid drive from the output. Otherwise, the speed of the internal combustion engine and / or the electrical machine could be pushed too far, which can cause the internal combustion engine to stall.

However, when the starting clutch opens, the electrical machine can no longer provide recuperation torque at the output, so that the braking effect of the electrical machine is then lost. In this case, the requested braking torque can then no longer be provided at the output, so that the hybrid vehicle then no longer brakes or decelerates as desired. This must be avoided for security reasons.

In order to take this problem into account, in a hybrid vehicle, when the same braking torque is made available via the electrical machine in recuperation mode when the same braking torque is provided on the output, the braking recuperation torque provided by the electrical machine is reduced early and the brake intervention of the service brake is increased accordingly, so that as a result of the Opening the starting clutch does not create a safety problem. However, this reduces the efficiency of the operation of the hybrid vehicle and thus its efficiency.

There is therefore a need for a method for operating a drive train of a hybrid vehicle, by means of which a hybrid vehicle can be operated more efficiently and with greater efficiency, namely in that the braking can be carried out for as long as possible via the electric machine and therefore as long and as long as possible A lot of braking torque is made available via the electrical machine in the recuperation mode of the same at the output.

Proceeding from this, the object of the invention is to create a novel method for operating a drive train of a hybrid vehicle. Another task is to provide a control system that is suitable for this purpose.

This object is achieved by a method according to claim 1. The further object is achieved by the features of patent claim 10. Advantageous refinements result from the subclaims, the description and the figures.

According to the invention, the transmission control determines, depending on the gear, an opening speed threshold for a transmission input speed, when the starting clutch begins to open, or a status signal of the starting clutch.

According to the invention, the transmission control provides the opening speed threshold or the status signal of the hybrid control and / or the brake control.

Then, when the transmission control provides the opening speed threshold or the status signal to the brake control, the brake control, depending on the opening speed threshold or the status signal, distributes a requested braking torque as a recuperation torque to the electric machine and / or as a friction torque to the service brake and provides the recuperation torque to the hybrid control.

Then, when the transmission control provides the opening speed threshold or the status signal of the hybrid control, the hybrid control, depending on the opening speed threshold or the status signal, distributes a requested braking torque as a recuperation torque to the electrical machine and / or as a friction torque to the service brake and provides the friction torque to the brake control.

The present invention proposes that the transmission control, depending on the gear, i.e. depending on the gear engaged in the transmission, determine an opening speed for the transmission input speed at which the starting clutch begins to open, or a status signal of the starting clutch and the hybrid control and / or the brake control provides to distribute a requested braking torque as a recuperation torque to the electric machine and / or as a friction torque to the service brake depending on the opening speed threshold or depending on the status signal.

The brake control and / or the hybrid control are accordingly at their disposal at which speed the starting clutch starts to open in an engaged gear or what the status of the starting clutch is, i.e. whether the starting clutch remains closed for a long time or will open shortly. Accordingly, it is not necessary to reduce a braking recuperation torque at an early stage; rather, as long as possible, a maximum proportion of a requested braking torque can be provided as a recuperation torque via the electrical machine on the output. In this respect, the hybrid vehicle can be operated efficiently and with high efficiency in braking operation without a safety risk.

If the transmission input speed is more than a limit value above the opening speed threshold, or if the status signal corresponds to a closed starting clutch, the brake control or the hybrid control system distributes the requested braking torque in such a way that the electric machine provides the maximum possible recuperation torque and the service brake provides the difference between the requested braking torque and the maximum possible recuperation torque. If the transmission input speed is less than the limit value above the opening speed threshold, or if the status signal corresponds to an opening clutch to be opened, the brake controller or the hybrid controller distributes the requested braking torque in such a way that it starts from the recuperation torque provided by the electric machine the maximum possible recuperation torque is reduced and the friction torque provided by the service brake is increased accordingly. This enables particularly efficient operation of the hybrid vehicle with particularly high efficiency.

According to an advantageous development of the invention, the transmission control determines the opening speed threshold and makes the opening speed threshold available to the hybrid control. Depending on the opening speed threshold, the hybrid control then distributes a requested braking torque as a recuperation torque to the electrical machine and / or as a friction torque to the service brake and provides the friction braking torque to the brake control.

The hybrid control preferably continues to select gears for the transmission and provides the gear selection of the transmission control. The hybrid controller preferably selects the gears for the transmission such that when the transmission input speed is less than a limit value above the opening speed threshold, the hybrid controller requests a downshift. With this advantageous development, the efficiency and thus the efficiency for a hybrid vehicle can be increased further. If the hybrid controller requests downshifts in the transmission depending on the opening speed threshold, a braking torque can be provided as a recuperation torque for as long as possible via the electric machine on the output, even in low gears.

According to an advantageous development of the invention, the transmission control determines the opening speed threshold or the status signal as a function of an idling speed, with the transmission control using an idling speed of the internal combustion engine as the idling speed when the internal combustion engine is coupled, and wherein the transmission control using a virtual idling speed of the electrical machine as the idling speed. The transmission control system also determines the opening speed threshold or the status signal depending on an offset with which it calculates the idling speed. The transmission control determines the offset depending on a gradient of the speed of the output and / or depending on a gradient of an actuation of a brake pedal. This determination of Opening speed threshold or the status signal is particularly preferred and allows an efficient operation of a hybrid vehicle with high efficiency.

• 1 eine schematisierte Darstellung eines Antriebsstrangs eines Hybridfahrzeugs;
• 2 ein Zeitdiagramm zur weiteren Verdeutlichung der Erfindung.

Preferred further developments result from the subclaims and the following description. Exemplary embodiments of the invention are explained in more detail with reference to the drawing, without being restricted to this. It shows:

• 1 a schematic representation of a drive train of a hybrid vehicle;
• 2nd a timing diagram to further illustrate the invention.

1 shows the basic structure of a drive train of a hybrid vehicle, the drive train being a hybrid drive 1 with an internal combustion engine 2nd and an electrical machine 3rd includes. Between the hybrid drive 1 and an output 4th is a gear 5 switched, which is designed as an automatic or automated transmission. The gear 5 converts speeds and torques and thus represents the tractive power offer of the hybrid drive 1 on the output 4th ready.

Between the internal combustion engine 2nd of the hybrid drive and the electric machine 3rd the same is a disconnect clutch 6 switched. Then when the disconnect clutch 6 is open is the internal combustion engine 2nd uncoupled and it is then driven purely electrically. With the disconnect clutch closed 6 is the internal combustion engine 2nd coupled and it can be hybrid via both the internal combustion engine 2nd as well as about the electrical machine 3rd be driven.

The drivetrain of the 1 still has an electrical energy storage 7 , the energy for the operation of the electrical machine 3rd provides. The one in the electrical energy storage 7 stored energy is via power electronics 15 for motorized operation of the electrical machine 3rd utilized. In the recuperation mode of the electrical machine 3rd can about the power electronics 15 the electrical energy storage 7 Loading.

1 still shows a starting clutch 20th which in the embodiment of the 1 in the transmission 5 is integrated. Is the starting clutch 20th in the transmission 5 integrated, so the starting clutch 20th through a switching element of the transmission 5 be formed, which for gear formation of the transmission 5 contributes. The starting clutch integrated in this way 20th can be designed as a multi-plate clutch or as a multi-plate brake. The starting clutch 20th can also be a clutch external to the gearbox, which is between the electrical machine 3rd and the gear 5 is switched.

On the downforce 4th acts as a service brake 18th a. Via the service brake 18th the drive train can be decelerated, in particular depending on the driver's actuation of a brake pedal 19th of the hybrid vehicle.

The hybrid vehicle is operated by a control system 8th controlled and / or regulated.

The control system 8th includes an engine control 9 , a transmission control 10th and a hybrid controller 11 . The engine control 9 controls and / or regulates the operation of the internal combustion engine 1 . The transmission control 10th controls and / or regulates the operation of the transmission 5 . The hybrid control 11 controls and / or regulates the operation of the electrical machine 3rd . Here is in 1 the engine control 9 in an engine control unit 12 , the transmission control 10th in a transmission control unit 13 and the hybrid control 11 in a hybrid control unit 14 implemented. It is also possible that transmission control 10th and hybrid control 11 are implemented in a common control unit.

In the sense of in 1 The double arrows shown exchange the engine control unit 12 and with it the engine control 9 with the internal combustion engine 1 , the hybrid control unit 14 and thus the hybrid control 11 with the electric machine 3rd and the transmission control unit 13 and thus the transmission control 10th with the gear 5 Data from. The control units also replace 12 , 13 and 14 data from one another. The hybrid control unit also swaps 14 Data with the electrical energy storage 7 out of that with a voltage converter 16 cooperates.

The control system 8th further comprises a brake control device which has a brake control 17th provides. The brake control unit swaps in particular with the brake pedal 19th and the transmission control unit 10th Data from.

The above data exchange is preferably carried out via at least one so-called CAN data bus. Details of such a CAN data bus are familiar to the expert addressed here.

The present invention is concerned with the fact that the control system 8th enables the hybrid vehicle to operate as efficiently as possible with high efficiency when braking the hybrid vehicle, for which purpose as much and as long as possible via the electric machine in braking operation 3rd in the recuperation mode of the same Braking torque on the output 4th should be provided.

In order to make this possible, the transmission control device determines 10th gear dependent, i.e. dependent on the gearbox 5 engaged non-positive gear, an opening speed threshold for the transmission input speed, when the starting clutch is reached 20th begins to open. Alternatively, the transmission control determines 10th a status signal of the starting clutch 20th , which provides information about whether the starting clutch 20th is closed, or whether the starting clutch is opened soon 20th is to be expected.

The transmission control device 10th sets the determined opening speed threshold or the determined status signal of the hybrid control 11 and / or the brake control 17th ready.

Then when the transmission control 10th the opening speed threshold of the starting clutch 20th or the status signal of the starting clutch 20th the brake control 17th provides, shares the brake control 17th depending on the opening speed threshold or the status signal, a requested braking torque, in particular via a driver's actuation of the brake pedal 19th requested braking torque, as recuperation braking torque on the electrical machine 3rd and / or as a frictional torque on the service brake 18th and sets the recuperation torque of the hybrid control 11 ready. The brake control then controls the service brake 18th to provide braking torque and hybrid control 11 the electrical machine 3rd to provide the recuperation torque.

Then when the transmission control 10th the opening speed threshold of the starting clutch 20th or the status signal of the starting clutch 20th the hybrid control 11 provides, shares the hybrid controller 11 Depending on the opening speed threshold or the status signal, the requested braking torque as recuperation torque on the electrical machine 3rd and / or as a frictional torque on the service brake 18th and then sets the friction torque of the brake control 17th ready with the hybrid control 11 the electrical machine 3rd to provide the recuperation torque and brake control 17th the service brake 18th to provide the friction torque at the output 4th controls.

Then when the transmission input speed is more than a limit above the opening speed threshold, or when the status signal of a closed and kept starting clutch 20th corresponds to the brake control 17th or the hybrid control 11 the requested braking torque so that the electrical machine 3rd provides a maximum possible recuperation torque and the service brake 18th only the difference between the requested braking torque and the maximum possible recuperation torque is provided, that is, in extreme cases, a friction torque of zero.

Then when the transmission input speed is less than the limit value above the opening speed threshold or when the status signal of a starting clutch to be opened or soon to be opened 20th corresponds to the brake control 17th or the hybrid control 11 the requested braking torque in such a way that it corresponds to that of the electrical machine 3rd Recuperation torque provided is reduced from the maximum possible recuperation torque, in particular linearly along a ramp to zero, and correspondingly that from the service brake 18th Provided friction torque increased so that a total torque from the recuperation torque and the friction torque to provide the requested braking torque remains constant.

The transmission control unit 10th determines the opening speed threshold or the status signal depending on an idling speed.

Then when the internal combustion engine 2nd with the disconnect clutch closed 6 to the transmission 5 coupled, the idle speed is the idle speed of the internal combustion engine 2nd .

Then when the disconnect clutch is open 6 the internal combustion engine 2nd from the gearbox 5 is decoupled, the idle speed is a virtual idle speed of the electrical machine 3rd , i.e. a minimum speed at which the electrical machine 3rd to rotate, for example to maintain a hydraulic oil supply.

The transmission control system takes care of this 10th the idling speed with an offset in order to determine the opening speed threshold or the status signal as a function thereof, this offset preferably depending on a gradient of the speed of the output 4th and / or from a gradient of an actuation of the brake pedal 19th is determined.

Further details of the invention are described below with reference to FIG 2nd described, wherein in 2nd over time t, several time waveforms or waveforms 21st , 22 , 23 , 24th , 25th and 26 are shown. So the signal curve corresponds 21st a speed curve at the input of the transmission 5 . A waveform 22 visualizes one from the transmission control 10th determined opening speed threshold for the starting clutch 20th . A waveform 23 visualizes a speed curve on the output side behind the starting clutch 20th . A curve 24th illustrates a driver's actuation of the brake pedal 19th . A waveform 25th visualizes one of the electrical machine 3rd on the output 4th provided regenerative braking torque and a curve 26 one from the service brake 18th on the output 4th provided friction braking torque.

Before the time t1 the hybrid vehicle rolls in a fixed gear with the brake pedal not depressed and the accelerator pedal depressed, with the transmission control 10th an opening speed threshold 22 for the starting clutch 20th determined.

At the time t1 the driver presses the brake pedal 19th that by the time t2 increases, starting with the time t2 therefore a defined braking torque 24th is requested. The hybrid control 11 or the brake control 17th shares this requested braking torque 24th on the electrical machine 3rd and / or the service brake 18th on, and in such a way that as much of this braking torque as possible as a recuperation torque 25th about the electric machine 3rd on the output 4th is provided and that the rest of the requested braking torque 24th that over the maximum of the electrical machine 3rd available recuperation torque goes beyond the friction braking torque 26 via the service brake 18th on the output 4th provided.

At the time t3 reaches the input speed 21st of the transmission 5 a value, so at the time t3 the transmission input speed 21st by less than the limit above the opening speed threshold 22 for the starting clutch 10th lies. Therefore, starting at the time t3 subsequently the requested braking torque 24th such from the brake control 17th or the hybrid control 11 split that same from the electrical machine 3rd provided recuperation moment 25th between the times t3 and t4 starting from the maximum possible recuperation torque, in particular along a ramp to zero, and that from the service brake 18th provided friction torque 26 is increased accordingly along a ramp, so that the total requested braking torque 24th can be provided.

At the time t4 is the starting clutch 20th opened, then only braking torque is applied via the service brake 18th on the output 4th provided.

Between the times t3 is the recuperation moment of the electrical machine 3rd maximum to the electrical energy storage 7 to be able to charge as efficiently as possible. Can the electrical machine between times t2 and t3 the total requested braking torque as the recuperation torque 24th provide, is between the times t2 and t3 that of the service brake 18th as friction torque at the output 4th provided braking torque zero.

2nd can be seen that depending on the actuation of the brake pedal 19th the opening speed threshold 22 increases. As stated above, the opening speed threshold 22 determined depending on the idle speed and the offset, the offset being preferably dependent on the brake pedal actuation. This training is based on the knowledge that the higher the actuation of the brake pedal 19th and the greater the deceleration of the hybrid vehicle, the less time it takes to open the starting clutch 20th is available. In this respect, the opening speed threshold must then 22 can be raised, for example, to stall the internal combustion engine 1 to prevent safely.

Following the date t4 after opening the starting clutch 20th , the speed of the internal combustion engine 1 or the electrical machine 3rd kept at idle speed. The speed behind the starting clutch 20th is further reduced by braking until the hybrid vehicle comes to a stop.

In the embodiment of the 2nd it was assumed that the transmission control 10th the opening speed threshold 22 determined. As already stated, it is also possible for the method to use a status signal for the starting clutch 20th he follows. When the invention uses a status signal, less data has to be transmitted via the CAN data bus, so that the CAN data bus is relieved.

But also when determining and transmitting a gear-dependent opening speed threshold for the starting clutch 20th the amount of data to be transmitted via the CAN data bus can be kept low. The number of signals to be transmitted can be kept low by only transmitting a signal for the opening speed threshold and, on the other hand, a counter signal, the counter signal indicating the gear. The counter can, for example, count the gears in a circle and so there can be a clear assignment between the gears and the opening speed threshold when only two signals are transmitted via the CAN data bus.

Then when the transmission control 10th the opening speed threshold for the starting clutch 20th determined and the hybrid control 11 provides, according to an advantageous development of the invention it is provided that the hybrid control 11 in in this case not just a requested braking torque on the electrical machine 3rd and / or the service brake 18th as a recuperation torque and / or friction torque, but that the hybrid control 11 additionally a gear selection for the transmission 5 makes and the gear selection of the transmission control 10th provides. Depending on the hybrid control 11 gear selection then controls the transmission control 10th The gear 5 on.

Gear selection through the hybrid control 11 takes place in such a way that the recuperation moment is as long as possible via the electrical machine 3rd on the output 4th Can be provided, including the hybrid control 11 when the transmission input speed is less than a limit value above the opening speed threshold for the starting clutch 10th requests a downshift. This enables recuperation down to low gears.

The control system according to the invention 8th enables efficient operation of a hybrid vehicle with high efficiency.

Reference symbol list

1

Hybrid drive

2nd

Internal combustion engine

3rd

electrical machine

4th

Downforce

5

transmission

6

Separating clutch

7

Energy storage

8th

Control system

9

Engine control

10th

Transmission control

11

Hybrid control

12

Engine control unit

13

Transmission control unit

14

Hybrid control unit

15

Power electronics

16

Voltage converter

17th

Brake control

18th

Service brake

19th

Brake pedal

20th

Starting clutch

21st

Curve shape

22

Curve shape

23

Curve shape

24th

Curve shape

25th

Curve shape

26

Curve shape

QUOTES INCLUDE IN THE DESCRIPTION

This list of documents listed by the applicant has been generated automatically and is only included 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.

Patent literature cited

• DE 102012204475 A1 [0002]

Claims (10)

Method for operating a drive train of a hybrid vehicle, the drive train comprising a hybrid drive (1) with an internal combustion engine (2) and an electrical machine (3), a transmission (5) connected between the hybrid drive (1) and an output (4) Starting clutch (20) and a service brake (18) acting on the output (4), with a transmission control (10) for controlling and / or regulating the operation of at least the transmission (5), with a hybrid control (11) for control and / or regulating the operation of at least the electrical machine (3), with a brake control (17) for controlling and / or regulating the operation of at least the service brake (18), characterized in that the transmission control (10) depends on the gear, an opening speed threshold for a transmission input speed when the starting clutch (20) is reached, or a status signal from the starting clutch (20) is determined, the transmission control (10) determines the opening speed elle or the status signal of the hybrid controller (11) and / or the brake controller (17) provides, wherein if the transmission control (10) provides the opening speed threshold or the status signal of the brake controller (17), the brake controller (17) depending on the opening speed threshold or distributes the requested braking torque as a recuperation torque to the electrical machine (3) and / or as a frictional torque to the service brake (18) and provides the recuperation torque to the hybrid control (11), when the transmission control (10) opens the opening speed threshold or the status signal provides the hybrid controller (11), the hybrid controller (11), depending on the opening speed threshold or the status signal, distributes a requested braking torque as a recuperation torque to the electric machine (3) and / or as a friction torque to the service brake (18) and the friction torque of the brake controller (17 ) provides. Procedure according to Claim 1 , characterized in that when the transmission input speed is more than a limit value above the opening speed threshold, or when the status signal corresponds to a closed starting clutch (20), the brake control (17) or the hybrid control (11) distributes the requested braking torque in this way that the electrical machine (3) provides a maximum possible recuperation torque and the service brake (18) provides the difference between the requested braking torque and the maximum possible recuperation torque. Procedure according to Claim 2 , characterized in that when the transmission input speed is less than the limit value above the opening speed threshold, or when the status signal corresponds to an opening clutch (20) to be opened, the brake control (17) or the hybrid control (11) provides the requested braking torque in this way divides that it reduces the recuperation torque provided by the electrical machine (3) based on the maximum possible recuperation torque and increases the frictional torque provided by the service brake (18) accordingly. Procedure according to one of the Claims 1 to 3rd , characterized in that the transmission control (10) determines the opening speed threshold and provides the opening speed threshold to the hybrid control (11), the hybrid control (11) depending on the opening speed threshold a requested braking torque as a recuperation torque on the electrical machine (3) and / or as a friction torque distributes the service brake (17) and provides the friction braking torque to the brake control (11), and the hybrid control (11) continues to select gears for the transmission (5) and provides the gear selection of the transmission control (10). Procedure according to Claim 4 , characterized in that the hybrid controller (11) requests a downshift when the transmission input speed is less than a limit value above the opening speed threshold. Procedure according to one of the Claims 1 to 5 , characterized in that the transmission control (10) determines the opening speed threshold or the status signal as a function of an idling speed, the transmission control (10) using an idling speed of the internal combustion engine (2) as the idling speed when the internal combustion engine (2) is connected, and wherein when the internal combustion engine is uncoupled ( 1) the transmission control (10) uses a virtual idle speed of the electrical machine (3) as idle speed. Procedure according to Claim 6 , characterized in that the transmission control (10) determines the opening speed threshold or the status signal depending on an offset with which it calculates the idling speed. Procedure according to Claim 7 , characterized in that the transmission control (10) determines the offset depending on a gradient of the speed of the output (4). Procedure according to Claim 7 or 8th , characterized in that the transmission control (10) the Offset is determined depending on a gradient of an actuation of a brake pedal (19). Control system (8) which is set up to carry out a method according to at least one of the preceding claims.

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