WO2018162236A1

WO2018162236A1 - Method for performing launch control drives in a hybrid vehicle

Info

Publication number: WO2018162236A1
Application number: PCT/EP2018/054262
Authority: WO
Inventors: Stephan Schaefer; Marko Marchlewski
Original assignee: Volkswagen Aktiengesellschaft
Priority date: 2017-03-06
Filing date: 2018-02-21
Publication date: 2018-09-13
Also published as: DE102017203623A1

Abstract

The invention relates to a method for preforming a start process of a motor vehicle having a hybrid drive train comprising an output shaft (9), a start element (5) and an internal combustion engine (1) with a drive shaft and an electric machine (2) that can be connected to the drive shaft of the internal combustion engine (1), wherein during the start process, the electric machine (2) is operated as a generator for biasing the internal combustion engine (1).

Description

description

Method for launching LaunchControl approaches in a hybrid vehicle

The invention relates to the field of motor vehicle transmissions, in particular a method for carrying out LaunchControl approaches ("racing starts").

In the known methods for carrying out LaunchControl approaches is the

Driveline already biased before the actual start. For example, toughening promotes throughput through the turbocharger so that when the brake is released by the driver, power can be demanded spontaneously. So far, to bias the

Internal combustion engine used the starting clutch.

German patent document DE 103 05 297 A1 discloses, for example, a method for controlling a start-up procedure of a motor vehicle that can be selected by the driver in connection with a start-up procedure ("LaunchControl") .This LaunchControl enables optimum vehicle acceleration on an off-road surface. eg by deactivating the slip control system or putting it into sports mode when the vehicle is stationary, selecting a specific driving program, setting the selector lever to a specific position when the vehicle is stationary, or / and pressing the brake while the accelerator pedal is fully depressed then prepared by the engine speed is adjusted to a fixed value with partially open ("slipping") clutch. By releasing the selector lever or alternatively the

Brake pedal accelerates the vehicle; i.e. the prepared starting process is

then by means of clutch control in the sense of optimal acceleration

continued.

However, the pretensioning leads to a thermal stress on the coupling. The energy from the fuel is converted into thermal energy, which leads to a

Clutch load leads. The power delivered by the engine is converted into unusable thermal energy. It requires a high cooling capacity.

From US Patent 9,067,593 B2, a LaunchControl system for a hybrid vehicle with a continuously variable transmission (eCVT) is known, at which engine speed and motor torque are controlled independently of the wheel speed and the wheel torque. The torque of the internal combustion engine can be counteracted by a torque from a motor generator and by activation of the brake pedal by the driver. However, the approach control system has the disadvantage that it is intended for a hybrid vehicle that has no startup clutch.

The object of the present invention is to provide a method and a correspondingly set up control for carrying out a starting operation of a motor vehicle with a starting clutch, which at least partially overcomes the abovementioned disadvantages.

This object is achieved by the method according to claim 1, as well as the correspondingly established control according to claim 8. Further advantageous

Embodiments of the invention will become apparent from the subclaims and the following description of preferred embodiments of the present invention.

The following embodiments relate to a method for performing a

Starting operation of a motor vehicle with hybrid powertrain with starting element, such as a converter or a starting clutch. The method can in particular

Hybrid vehicles, especially in hybrid vehicles with dual-clutch transmission are used.

The motor vehicle has a hybrid drive train having an output shaft and a

Starting element, such as a converter or a starting clutch has, and an internal combustion engine with an output shaft and an electric machine, with the

Output shaft of the engine is connectable. The internal combustion engine is preferably a supercharged VKM engine provided with a turbocharger.

During the starting process, the electrical machine is operated as a generator to bias the internal combustion engine. By biasing the internal combustion engine by means of a generator-operated electric machine instead of by means of starting clutch, a thermal load of the starting clutch can be avoided.

According to a preferred embodiment, for biasing the internal combustion engine, the electric machine is operated as a generator in order to charge a battery, for example a high-voltage battery. Thus stands for the following acceleration process more electrical energy in a high-voltage battery available. The energy for tempering is not cooled away, but reused for earmarked purpose.

The hybrid powertrain may further include a disconnect clutch between the engine and the electric machine. By closing the clutch, the

Combustion engine are loaded to build boost pressure for the starting process.

According to a preferred embodiment, in the method according to the invention, the state of charge of a high-voltage battery is checked in order to detect whether a generator operation of the electrical machine is possible. If the battery is fully charged, the

Internal combustion engine are not biased. But then, conversely, it is ensured that the electric machine can provide a complete instation equalization, so that in both cases the implementation of a full-fledged LaunchControl is guaranteed.

According to an alternative embodiment, the biasing of the internal combustion engine can also be done by loading the internal combustion engine with a belt starter generator.

The boot process can be a LaunchControl start. The method can be used for example in the context of a LaunchControl. The

LaunchControl, for example, optimally accelerates a vehicle with an automated manual transmission to maximum speed. As part of a LaunchControl, the automatic shift can be controlled so that when starting up the speed is applied, which accelerates the vehicle with optimized wheel slip from a standstill the best.

The present invention also relates to a controller adapted to carry out the methods described above. The control may be, for example, a transmission control and / or a motor control.

The method according to the invention can be implemented, for example, as a computer-implemented method in a controller which has one or more processors, memory and communication interfaces. In particular, the process may take the form of

Program instructions that are executed on a processor, e.g. one

Transmission control module to be executed. The invention is thus also a

A processor arranged to implement the described method or to controllers comprising a processor arranged in this way. Also, a motor vehicle is subject of this invention, which includes such control. The motor vehicle may be, for example, a hybrid vehicle

Combustion engine and generator operable electric machine act.

Embodiments of the invention will now be described by way of example and with reference to the accompanying drawings, in which:

Fig. 1 shows schematically an embodiment of a drive train of a hybrid vehicle;

FIG. 2 shows exemplary controls of a motor vehicle for launching LaunchControl approaches; FIG. and

Fig. 3 shows an embodiment of a method for performing LaunchControl approaches.

Fig. 1 shows schematically an embodiment of a drive train of a hybrid vehicle. The figure provides a schematic and exemplary schematic representation of a

torque adding parallel hybrid drive concept. The drive concept may be, for example, a plug-in hybrid powertrain having a single-shaft parallel hybrid drive train or the like. A parallel hybrid powertrain of a hybrid vehicle includes an engine 1, a dual mass flywheel 8 (ZMS), an electric machine 2 (EM), a transmission 3, and a differential 4. Between electric machines 2 and

Internal combustion engine 1 is a controllable separating clutch 10. The electric machine 2 and the internal combustion engine 1 are coupled to an output shaft 9. The transmission 3 comprises a starting clutch 5. The transmission 3 is designed, for example, as an electro-hydraulically actuated double-clutch transmission, but other types of clutch or transmission may also be used. Serving as a traction battery high-voltage battery 6 provides electrical energy power electronics 7 available, which operates the electric machine 2. The electric machine 2 can be operated as a generator. With the help of the clutch 10 (hybrid clutch or Wiederstartkupplung) of the

Combustion engine 1 are coupled to the transmission 3. Among other things, the hybrid vehicle can be operated in the operating modes "electric driving" and "recuperation". Further, the engine 1 can be operated at full power, and in addition, the electric machine 2 can provide a torque to increase the total torque (boosting). If the starting clutch 5 is used for pretensioning of the internal combustion engine, this leads to a thermal load on the starting clutch 5. For this reason, in the method described here for carrying out LaunchControl approaches during the

Biasing the internal combustion engine 1 is not burdened by the transmission clutch 5, but otherwise. In particular, in the method according to the invention in a hybrid vehicle, the high-voltage battery 6 is charged with high power in order to drive the internal combustion engine 1

pretension. As a result, a thermal load on the starting clutch 5 can be avoided. In addition, more electrical energy in the high-voltage battery 6 is available for the following acceleration process. The energy for tempering is not cooled away, but reused for earmarked purpose.

According to one embodiment of the invention, the internal combustion engine 1 is loaded with the electric machine in order to build up boost pressure for the start. This has the advantage that the internal combustion engine 1 can deliver the power required for a race start. This loading of the internal combustion engine 1 can by the output shaft 9 of the

Internal combustion engine connected generator-operated electric machine 2 done by, for example, the clutch 10 between the engine 1 and electric machine 2 is closed.

Fig. 2 shows exemplary controls of a motor vehicle. A motor vehicle in this embodiment comprises an engine controller 1 1 for controlling the internal combustion engine 1, and a transmission controller 12 for controlling at least the transmission 3 with the starting clutch 5 (e.g., dual clutch) and the disconnecting clutch 10. The transmission controller 12 and the engine controller 1 1 are based for example on microprocessors and memory modules, as well as communication interfaces. The controls 11 and 12 are programmed to carry out the required steps of the starting control method according to the invention, for example the method described in the following Figure 3. Engine control 1 1 and transmission control 12 may be communicatively coupled with each other. Also, engine controller 11 and transmission controller 12 could be realized as a controller,

for example as a processor.

3 shows an exemplary embodiment of a method for carrying out a LaunchControl start. In a step 301, the LaunchControl mode of the vehicle is activated. This can be done, for example, by the driver pressing a corresponding selection key of the

Dashboard operated, which sets a launch control bit in the engine control accordingly. At step 302, the method detects that the vehicle brakes are being applied by the driver, which is a prerequisite for launching LaunchControl startup. At step 303, the method detects an accelerator operation of the driver. Upon detection of the accelerator pedal operation in step 303, the transmission control closes the disconnect clutch and thereby couples the engine to the output shaft at step 304. The transmission control now automatically adjusts a desired speed of the internal combustion engine, eg of the

Torque request by the driver, the state of charge of the high-voltage battery or other parameters may be dependent. For this purpose, the engine control unit is sent the desired / stall speed via the synchronous speed interface, for example. At step 305, it is checked whether the high-voltage battery has enough charging capacity to allow regenerative operation of the electric machine. Exceeds the state of charge of

High-voltage battery a predefined threshold (or is the high-voltage battery already fully charged), so a generator operation of the electric machine is not possible because the energy generated by the electric machine can not be dissipated. In this case, the method continues with step 306. At step 306, a reduced starting torque of the internal combustion engine is built up without bias, and the startup process according to steps 309 and 310 is continued. Due to the delayed filling of the air gap of the

Internal combustion engine results in a delayed torque build-up, which, however, can be completely compensated for by a corresponding instation equalization by the electric machine due to the fully available battery charge. At the

Instationärausgleich the electric machine compensates for torque from the

Internal combustion engine can not be provided. The electric machine is used due to the full battery charge to perform required torque changes quickly and with good efficiency. A biasing of the internal combustion engine by the electric machine is not required in this case. On the other hand, if it is detected in step 305 that the high-voltage battery is not full, the method continues with step 307. At step 307, the internal combustion engine is biased against the electric machine. Here, the torque of the engine via the output shaft of the

Internal combustion engine transferred to the electric machine and recorded by this. As a result, the internal combustion engine is biased. The electrical machine converts the mechanical power absorbed by it into electrical power, thereby charging the high-voltage battery of the vehicle. In this case, the engine starting torque is fully established in step 308. In a step 309, the release of the vehicle brakes is detected. After releasing the vehicle brakes in step 310 closes the

Transmission control the starting clutch and at the same time the charging power (negative torque) of the electric machine is switched off, or in the boost mode (positive torque the electric machine) switched. As a result, torque is transmitted to the vehicle wheels, the vehicle is set in motion with a prestressed internal combustion engine.

List of Reference Number Combustion Engine (VKM)

electric machine (EM)

transmission

differential

Starting clutch / double clutch

High-voltage battery

power electronics

Dual Mass Flywheel

Output shaft of the internal combustion engine

Disconnect clutch (restart clutch)

motor control

transmission control

Claims

claims

1. A method for performing a starting operation of a motor vehicle with a hybrid drive train comprising a starting element (5) and an internal combustion engine (1) having an output shaft and an electric machine (2) connectable to the output shaft (9) of the internal combustion engine (1) is at the startup process for biasing the

Internal combustion engine (1) the electric machine (2) is operated as a generator.

2. The method of claim 1, wherein the internal combustion engine is a supercharged VKM engine.

3. The method of claim 1 or 2, wherein for biasing the internal combustion engine (1), the electric machine (2) is operated as a generator to charge a battery (6).

4. The method according to any one of claims 2 or 3, wherein the hybrid powertrain between the internal combustion engine (1) and electrical machine (2) further comprises a separating clutch (10) and by closing the separating clutch (10) of the internal combustion engine (1) is loadable to boost pressure to build up for the boot process.

5. The method according to any one of the preceding claims, wherein further the state of charge of the battery (6) is checked to detect whether a regenerative operation of the electric machine (2) is possible.

6. The method of any one of the preceding claims, wherein the electric machine is a belt-starter-generator.

7. The method according to any one of the preceding claims, wherein it is in the

Startup process is a LaunchControl startup.

8. A controller adapted to carry out the method according to any one of the preceding claims.

9. Motor vehicle, with a controller according to claim 8.