DE102010007808A1 - Method and device for operating a hybrid vehicle drive, vehicle - Google Patents

Abstract

The method involves operating an electrical flywheel accumulator for generating a supply voltage in an electrical system in an operating mode. The supply voltage is high such that an electrical machine (16) is operated for a boost-operation of a vehicle drive. The operation of the electrical flywheel accumulator is provided in the operating mode also when no boost-operation of the vehicle drive is provided. Independent claims are also included for the following: (1) a device for controlling the operation of a hybrid vehicle drive; and (2) a motor vehicle for racing.

Description

STATE OF THE ART

The present invention relates to a method and apparatus for operating a hybrid vehicle drive drivable with an internal combustion engine and an electric machine. Furthermore, the present invention relates to a vehicle with a hybrid vehicle drive.

In general, a hybrid drive means that it has at least two different energy converters and two different energy stores. In practical implementation, the transducers are typically an internal combustion engine and an electric motor and the energy storage devices are a combustible fuel for the internal combustion engine and a rechargeable battery, a high-performance condenser or an electric flywheel storage as an electrical energy store for the electric motor.

Such a hybrid vehicle has over conventional vehicles with internal combustion engine the advantage that it can recover the braking energy to the loss of efficiency to a large extent. This feedback or intermediate storage of energy, ie the recuperation, occurs during active braking of the vehicle and in overrun operation, in which the internal combustion engine does not actively drive the vehicle and the vehicle is driven only by its own inertial mass on. The recovered, so recuperated braking energy is cached in the energy storage and can be retrieved as needed. The electric motor is operated here as a generator and works as a mechanical-electrical converter. In addition, a mechanical variant for the energy storage of the electric motor is possible, where a flywheel is accelerated by the braking process. The stored kinetic energy can then be returned to the drive axle at a later time via a continuously variable transmission. Such an energy recovery system is in the WO 2009/141646 A1 described.

In motor racing, the so-called KERS system (Kinetic Energy Recovery System) has been used for some time to recover kinetic energy. The stored kinetic energy is used here to operate the electric motor for a short time if necessary so that its power can be used in acceleration phases in addition to the internal combustion engine. Such phases, in which the internal combustion engine is assisted by an electric motor drive, are referred to as boost phases or boost operation.

This electric motor drive is powered by a DC link voltage of the high-voltage vehicle electrical system. However, this DC link voltage, which results from the induced voltages of an electric machine and an electric flywheel storage, is usually too low to provide an effective boost operation. For a boost operation, it is necessary to raise the intermediate circuit voltage to an efficient level for the electric machine.

For this purpose, z. B. the kinetic energy of the electric flywheel storage can be used by being operated as a generator and thus slowed down. As a result of this deceleration, the electric flywheel storage unit generates energy via which the original, comparatively small DC link voltage is raised to a higher DC link voltage. This high DC link voltage is sufficiently high for the electromotive drive to provide a comparatively effective boost operation with a desired performance. Following the boost operation, the electric flywheel accumulator is returned to a freely rotating operating mode in which the flywheel rotates without drive and brake. The DC link voltage then drops again. This comparatively low DC link voltage is energetically more favorable, since less energy is consumed here.

In certain applications and in particular in the racing sector, a high dynamics of the drive system is required. Here one would like, for example, that the boost operation can be used as quickly as possible. The problem, however, is that the lifting of the DC link voltage from the relatively low DC link voltage to the high DC link voltage required for the boost operation due to the inertia of the voltage regulation takes a certain amount of time. However, this gives a lower dynamics.

SUMMARY OF THE INVENTION

The present invention is based on the object to provide a more dynamic operation of a hybrid vehicle, especially under racing conditions.

According to the invention, this object is achieved by means of a method having the features of patent claim 1 and / or by means of a device having the features of patent claim 9 and / or by means of a vehicle having the features of patent claim 12.

• – Ein Verfahren zum Betreiben eines mit einer Brennkraftmaschine und einer elektrischen Maschine antreibbaren hybriden Fahrzeugantriebs, bei dem die elektrische Maschine und ein als elektrischer Schwungradspeicher vorgesehener Energiespeicher an ein Bordnetz ankoppelbar sind, mit einem ersten Betriebsmodus, bei dem der elektrische Schwungradspeicher zur Erzeugung einer ersten Versorgungsspannung im Bordnetz in einem generatorischen Betrieb betrieben wird, wobei die erste Versorgungsspannung derart hoch ist, dass die elektrische Maschine für einen Boost-Betrieb des Fahrzeugantriebs elektromotorisch betreibbar ist, und wobei der generatorische Betrieb des elektrischen Schwungradspeichers im ersten Betriebsmodus auch dann vorgesehen ist, wenn gerade kein Boost-Betrieb des Fahrzeugantriebs vorgesehen ist.
• – Eine Vorrichtung zum Steuern des Betriebs eines hybriden Fahrzeugantriebs, mit einer Steuervorrichtung, die dazu ausgelegt ist, eine elektrische Maschine des hybriden Fahrzeugantriebs entsprechend einem erfindungsgemäßen Verfahren zu steuern.
• – Ein Kraftfahrzeug, insbesondere ein für den Rennsport vorgesehenes Kraftfahrzeug, mit einem hybriden Fahrzeugantrieb, welches eine Brennkraftmaschine, eine elektrischen Maschine und einen als elektrischen Schwungradspeicher ausgebildeten Energiespeicher aufweist, mit einem Bordnetz zur Bereitstellung einer Hochvoltzwischenspannung, welches mit dem elektrischen Schwungradspeicher und der elektrischen Maschine verbunden ist, mit einer erfindungsgemäßen Vorrichtung.

Accordingly, it is provided:

• - A method for operating a drivable with an internal combustion engine and an electric machine hybrid vehicle drive, in which the electric machine and provided as an electrical flywheel energy storage can be coupled to a vehicle electrical system, with a first operating mode, wherein the electric flywheel storage for generating a first supply voltage is operated in the electrical system in a regenerative operation, wherein the first supply voltage is so high that the electric machine for a boost operation of the vehicle drive is operated by an electric motor, and wherein the regenerative operation of the electric flywheel in the first operating mode is also provided, if just no boost operation of the vehicle drive is provided.
• A device for controlling the operation of a hybrid vehicle drive, comprising a control device, which is designed to control an electric machine of the hybrid vehicle drive according to a method according to the invention.
• - A motor vehicle, in particular a motor vehicle intended for racing, with a hybrid vehicle drive, which has an internal combustion engine, an electric machine and designed as an electric flywheel energy storage, with a vehicle electrical system for providing a high-voltage intermediate voltage, which with the electric flywheel and the electric machine is connected, with a device according to the invention.

The underlying realization of the present invention is that a high dynamic of the intended as an electrical flywheel energy storage energy storage is required in the racing field or about when operating a hybrid motor vehicle driven under sporting conditions. Another finding is that this electric flywheel storage in a freely rotating operation, in which the DC link voltage in the (high-voltage) electrical system is located on an energy-saving, low voltage level, just this dynamic operation is not fair. The idea of the present invention is now, the electric flywheel storage z. B. in racing not even bring into the energy-saving, free-rotating state, but always to keep the electric flywheel storage on a required, relatively high voltage level of the DC link voltage. This high voltage level of the intermediate circuit voltage is sufficient to switch on the electric machine for a boost operation and also ensures high system performance and high efficiency. The vehicle electrical system thus permanently has a high intermediate circuit voltage in this mode. Due to the permanently higher voltage level of the intermediate circuit voltage in the electrical system during the first operating mode, although results in a higher energy consumption, which has a greater reduction in the speed of the electric flywheel storage result in idle mode. However, this higher energy consumption is deliberately accepted in favor of a desired for the racing sector or for the sporty operation of the vehicle high dynamics.

Advantageous embodiments and further developments of the invention will become apparent from the other dependent claims in conjunction with the figures of the drawing.

In a typical embodiment, the electric flywheel storage is alternately accelerated in the first operating mode and then operated again in generator mode. As the electric flywheel accumulator accelerates, the speed of the flywheel increases, thereby increasing the kinetic energy stored in the flywheel electric accumulator. If this is sufficiently high, the electric flywheel storage can be operated again in regenerative operation, in which the first supply voltage in the electrical system is increased again or at least stabilized.

In a likewise preferred embodiment, the speed of the flywheel of the flywheel electric storage device is permanently determined. If the speed of the flywheel of the electric flywheel storage decreases below a predetermined minimum speed, then the electric flywheel storage is accelerated again. This minimum speed is predetermined such that a largely constant power is provided by the electric flywheel storage up to this minimum speed. Below this minimum speed, for example, the power output of the electric flywheel storage decreases in such a way that no boost operation with desired system performance is possible.

In a particularly preferred embodiment, the first operating mode denotes a racing operation of the hybrid vehicle drive. Especially in this racing a very high dynamics is very beneficial.

In a typical embodiment, the vehicle is driven in boost mode both by the electric motor driven electric motor and by the internal combustion engine. It can be z. B. the internal combustion engine driving a first vehicle axle, such as the Rear axle, while the electric machine drives a second vehicle axle, such as the front axle. As a result, a switchable four-wheel drive is guaranteed, in which the electric machine is switched on to drive the front axle. It would also be conceivable, however, for the internal combustion engine to drive all axles or for the electric machine to drive both the front axle and the rear axle or only the rear axle. In the first operating mode, the electric machine preferably drives only a single axis and in particular the front axle of the vehicle.

In a particularly preferred embodiment, a second operating mode is provided. In this second mode of operation, the flywheel electric storage can be controlled in a freely rotating operation. In this free-rotating operation of the electric flywheel storage, the DC link voltage of the electrical system falls to a second supply voltage, which is less than the first supply voltage from. This second operating mode denotes a relation to the first operating mode energetically favorable operation. However, this is at the expense of momentum. Depending on whether an energetically favorable idling operation or a load operation with high dynamics is required, the electric flywheel storage is now operated in the second operating mode or in the first operating mode.

In a typical embodiment, the electrical system referred to a so-called high-voltage vehicle electrical system for operating the flywheel electric storage and the flywheel electric machine. The first supply voltage provided by the high-voltage vehicle electrical system indicates a voltage range of more than 350 volts, preferably more than 400 volts, and more preferably more than 440 volts. Additionally or alternatively, the second supply voltage designates a voltage range of less than 200 volts, preferably less than 160 volts, and more preferably less than 140 volts.

In a typical embodiment, the control device has a microcontroller or a microprocessor, which is connected via a control bus to corresponding control inputs of the electric machine and the electric flywheel storage. Typically, the control device is part of a control unit and in particular of the engine control.

Preferably, the apparatus also includes a speed sensor that is configured to determine the speed of rotation and / or the speed of the flywheel of the flywheel energy storage. Preferably, a voltage sensor is further provided, which is designed to detect the voltage in the electrical system. Depending on the speed of the flywheel of the flywheel electric storage and the voltage in the electrical system, the control device can operate the electric flywheel storage in the first operating mode or in the second operating mode.

The above embodiments and developments can, if appropriate, combine with each other as desired. Further possible refinements, developments and implementations of the invention also include combinations, not explicitly mentioned, of features of the invention described above or below with regard to the exemplary embodiments. In particular, the person skilled in the art will also add individual aspects as improvements or additions to the respective basic form of the present invention.

BRIEF CONTENT OF THE DRAWINGS

The present invention will be explained in more detail with reference to the exemplary embodiments indicated in the schematic figures of the drawing. It shows:

1 a schematic representation of a vehicle according to the invention;

2 a flow diagram for explaining a first embodiment of the method according to the invention;

3 a block diagram for an inventive device.

In the figures of the drawing are - unless otherwise stated - same and functionally identical elements each provided with the same reference numerals.

DESCRIPTION OF EMBODIMENTS OF THE INVENTION

1 shows a schematic representation of a vehicle according to the invention, which here with reference numerals 10 is designated. The vehicle 10 is here designed as hybrid drivable vehicle with a here only schematically and greatly simplified, coupled axle drive system. The vehicle 10 has an internal combustion engine 11 on, for example, in the rear of the vehicle 10 is arranged. This internal combustion engine 11 drives over a first conventional axle drive device 12 the two wheels (not shown here) of the rear axle.

The coupled drive system according to the invention also has a second electrical axle drive 14 on which at least one wheel and in the example shown, preferably both wheels of the front axle 15 drives. For this purpose, the electric drive device 14 for example, two electrical machines 16 on, each of which is an electric machine 16 a respective assigned wheel of the front axle 15 drives. These electrical machines 16 are preferably separate or at least independently formed and drive the respective wheels of the front axle 15 independently of each other. In principle, however, it would also be conceivable that only one electric machine 16 is provided, which drives both wheels of the front axle.

The electrical machines 16 Here are, for example, electric motors that can also be operated as a generator for recuperation, ie for the recovery and feedback of electrical energy. In electric motor operation these electric machines drive 16 via a respective spur gear or a propeller shaft to each assigned to her wheel. To supply the electrical machines 16 with energy is an electrical energy storage 17 intended. This electrical energy storage 17 is designed as an electric flywheel storage which, if necessary, its stored kinetic energy to the electric machine 16 emits.

Further, a control device 18 provided the operation of the electric machine and thus driving the two wheels of the front axle 15 controls. About the control device 18 can the vehicle 10 be operated in a two-wheeler or a switchable four-wheel drive. In two-wheeled operation, for example, only the rear axle 13 of the vehicle 10 over the internal combustion engine 11 driven. If necessary, a four-wheel drive can now be switched on. This connection can be set manually, for example by the driver of the motor vehicle, for example by pressing a button. It is particularly advantageous, however, if this four-wheel drive, depending on the particular driving situation fully automatically by the controller 18 is set. For example, it can be provided that the control device 18 when driving in a curve or even at a given torque of the rear axle 13 is switched on. As a result, the dynamics of the vehicle is stabilized, as now the front axle 15 is used for propulsion. Overall, this increases the dynamics and vehicle safety in these situations.

According to the invention is now the front axle 15 and thus the electrical machines 16 an electric flywheel storage (in 1 not shown). In this electric flywheel storage is a arranged in a vacuum cylinder and there virtually resistance-free rotatable wheel. This flywheel has a relatively high inertial mass and is thus suitable to store a high mechanical energy. Typically, this flywheel can rotate at high revolutions of up to 64,000 rpm. The flywheel is usually rotated by the electric motor (or a corresponding electric machine) and thereby accelerated. Preferably flywheel and electric machine are a combined component, in which, for example, the rotor of the electric flywheel storage is designed as a rotor of the electric machine. This flywheel is intended to provide the kinetic energy stored in the flywheel electric accumulator for driving an axle. The voltage level of the high-voltage vehicle electrical system during idling operation is generally not sufficient, however, to provide a boost operation, ie a high-output operation, in which the electric machines 16 the front axle 15 drive. For this purpose, a significantly higher voltage of, for example, over 400 volts and preferably of about 440 volts is provided. In order to realize this higher voltage level in the high-voltage on-board electrical system, this flywheel electric accumulator is decelerated slowly, whereby kinetic energy is reduced. At the same time, the electric flywheel accumulator operated in regenerative mode generates electrical energy which is fed into the high-voltage on-board electrical system and there causes a significant increase in the voltage level up to 440 volts. The electric machine 16 can now be operated with this high supply voltage and the front axle 15 or drive the wheels attached to it. This effectively provides a boost operation.

It should be noted that in addition to the high-voltage vehicle electrical system, which is required for the hybrid drive and the flywheel, a conventional motor vehicle electrical system is provided. This conventional motor vehicle electrical system is connected to the conventional vehicle battery and provides a significantly lower than the high voltage vehicle electrical system low voltage. This conventional motor vehicle electrical system, unlike the high-voltage vehicle electrical system, which has a variable supply voltage, typically has a fixed voltage of typically 12, 24 or 42 volts.

The electric flywheel storage 20 (please refer 4 ) can basically have the following three operating modes:

1. Free-spinning operation:

In this freely rotating operation, the flywheel of the electric rotates flywheel storage 20 largely free, ie without it giving off electrical energy to the high-voltage vehicle electrical system or receiving electrical energy from the high-voltage on-board electrical system. It turns here an energetically favorable supply voltage in the high-voltage vehicle electrical system.

2. Generator operation of the electric flywheel storage:

If the electric flywheel storage operated in generator mode, the flywheel is braked more or less strongly and thus gives its stored kinetic energy, which is fed in the form of electrical energy into the high-voltage vehicle electrical system. About the controller 18 becomes the rotational speed of the flywheel of the flywheel electric flywheel 20 monitored in this operation. The control device 18 ensures that this regenerative operation is maintained only until a minimum rotational speed n _{min of} the flywheel of the flywheel flywheel 20 is reached. At this minimum rotational speed n _{min of} the flywheel of the flywheel flywheel 20 is still ensured that a maximum power can be delivered to the high-voltage electrical system. At the end of this operation, the flywheel of the electric flywheel storage 20 typically either controlled in the free-rotating mode or accelerated again.

3. Acceleration of the electric flywheel storage:

In this operation, the flywheel of the electric flywheel storage 20 accelerated, for example mechanically or by the electric motor, to the kinetic energy of the flywheel of the flywheel flywheel 20 rebuild. Has the flywheel of the electric flywheel storage 20 reaches a predetermined maximum rotational speed n _max , for example, n _max ≈ 64,000 U / min, this operation is terminated. Subsequently, the flywheel of the electric flywheel storage 20 switch back to free-running operation or to regenerative operation.

Hereinafter, a particularly preferred embodiment of the operation of the electric flywheel storage 20 based on 2 explains:
For the first operating mode according to the invention, in step S1, the flywheel of the electric flywheel storage 20 initially accelerated. Is a maximum rotational speed n _{max of} the flywheel of the flywheel electric flywheel 20 is reached (step S2) then this acceleration operation of the flywheel of the electric flywheel storage 20 completed. It is then checked whether a boost operation of the hybrid drive is desired (step S3). If a boost operation is desired, then the flywheel of the electric flywheel storage 20 operated in regenerative mode in step S4. This is done as long as the boost operation is needed or up to which the flywheel of the flywheel electric storage has reached a minimum speed n _min (step S5). In this case, the process returns to step S1. If no boost operation is desired in step S3, then only monitoring of the rotational speed n of the flywheel of the electric flywheel storage takes place 20 until the minimum speed n _{min is reached} in step S5.

3 shows a block diagram for an inventive device for controlling the operation of a hybrid vehicle drive. In 3 is the electric machine 16 with the electric flywheel storage 20 via the high-voltage on-board electrical system 30 connected. Furthermore, a device according to the invention 31 intended. The device according to the invention 31 for controlling the operation of the hybrid vehicle drive has here the control device 18 on, which contains for example a microcontroller. Furthermore, the device 31 also a speed sensor 32 on, with the flywheel of the electric flywheel storage 20 coupled and which is adapted to the rotational speed and / or the rotational speed of the flywheel of the electric flywheel storage 20 to investigate. The speed sensor 32 is with the control device 18 connected to provide information about the determined speed. The device according to the invention 31 also has a voltage sensor 33 on, via which the voltage level or the voltage level in the high-voltage vehicle electrical system 30 can be determined. Corresponding information about the determined voltage in the high voltage on-board electrical system 30 represents the voltage sensor 33 the control device 18 to disposal. There is also a tax bus 34 provided, for example, a CAN bus, via which the control device 18 with the electric machine 16 and the flywheel of the electric flywheel storage 20 can communicate or via the the controller 18 the electric machine 16 and the electric flywheel storage 20 can control.

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

• WO 2009/141646 A1 [0003]

Claims (12)

Method for operating an engine with an internal combustion engine ( 11 ) and an electric machine ( 16 ) drivable hybrid vehicle drive, wherein the electric machine ( 16 ) and as electrical flywheel storage ( 20 ) provided energy storage to an electrical system ( 30 ) are coupled, with a first operating mode in which the electric flywheel storage ( 20 ) for generating a first supply voltage in the electrical system ( 30 ) is operated in a generator operation, - wherein the first supply voltage is so high that the electric machine ( 16 ) is electrically operated for a boost operation of the vehicle drive, and - wherein the regenerative operation of the electric flywheel storage ( 20 ) is also provided in the first operating mode when no boost operation of the vehicle drive is provided. The method of claim 1, wherein the flywheel of the electric flywheel storage ( 20 ) is first accelerated alternately in the first operating mode and then operated in a regenerative operation. Method according to Claim 2, in which the rotational speed of the flywheel of the electric flywheel accumulator ( 20 ) is determined and in which at a decrease in the rotational speed of the flywheel of the electric flywheel storage ( 20 ) below a predetermined minimum speed, the flywheel of the electric flywheel storage ( 20 ) is accelerated again in the first operating mode. Method according to one of the preceding claims, in which the first operating mode denotes a racing operation. Method according to one of the preceding claims, in which the vehicle ( 10 ) in boost mode both by the electric motor driven electric machine ( 16 ) and of the internal combustion engine ( 11 ) is driven. Method according to one of the preceding claims, in which in the first operating mode only one axis ( 13 . 15 ) and in particular the front axle ( 15 ) by the electric machine ( 16 ) is driven. Method according to one of the preceding claims, with a second operating mode, in which the flywheel of the electric flywheel accumulator ( 20 ) is controlled in a freely rotating operation, in which the electrical system ( 30 ) is lowered to a second supply voltage, which is lower than the first supply voltage. Method according to one of the preceding claims, wherein the vehicle electrical system is designed as a high-voltage on-board network and wherein the first supply voltage denotes a voltage range of more than 350 volts, preferably greater than 400 volts and more preferably greater than 440 volts, and / or wherein the second Supply voltage denotes a voltage range of less than 200 volts, preferably less than 160 volts, and more preferably less than 140 volts. Device for controlling the operation of a hybrid vehicle drive, comprising a control device ( 18 ), which is designed to be an electrical machine ( 16 ) of the hybrid vehicle drive according to a method according to any one of claims 1 to 8. Device according to claim 9, wherein the control device ( 18 ) a microcontroller ( 18 ) or a microprocessor, which via a control bus ( 34 ) with corresponding control inputs of the electric machine ( 16 ) and the electric flywheel storage ( 20 ) connected is. Device according to one of claims 9 or 10, with a rotational speed sensor ( 32 ), which is adapted to the rotational speed (s) and / or the speed of the flywheel of the flywheel electric storage ( 20 ) and / or with a voltage sensor ( 33 ), which is designed to reduce the voltage in the electrical system ( 30 ) of the motor vehicle ( 10 ) capture. Motor vehicle, in particular a motor vehicle intended for racing ( 10 ), - with a hybrid vehicle drive, which an internal combustion engine ( 11 ), an electric machine ( 16 ) and one as an electric flywheel storage ( 20 ) formed energy storage, - with a vehicle electrical system ( 30 ) for providing a high-voltage intermediate voltage which is connected to the electric flywheel storage ( 20 ) and the electric machine ( 16 ), - with a device according to one of claims 9 to 11.

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