DE19532325C2 - Method of operating a series hybrid drive - Google Patents

Description

The invention relates to a method for Operation of a series hybrid drive that burns motor with mechanically coupled generator, an electrically connectable to the generator drive electric motor and one to the generator and the Drive electric motor connectable energy storage includes, in an operating mode in which the Operation of the internal combustion engine is permitted at An demand for an increased drive power of the combustion engine from an operating state lower Power output in an operating state increased lei service charge is performed.

It is known that series hybrid drives with the ge named structure operated in different operating modes can be used by the drive ele trotoren their energy either from the energy source cher, e.g. B. a traction battery, or from the generator relate, which in turn from the internal combustion engine is drivable. Such series hybrid drives are found especially used in motor vehicles. In areas in which generate no combustion engine exhaust gases the vehicle will run out of energy the energy storage operated. Outside of such ge offers the combustion engine activated and its Energy via the generator drive electric motor be fed to the range and / or the To increase the mileage of the vehicle. Acquaintance these two operating modes can measure. H. Energy storage operation on the one hand and generator-supported Operation on the other hand, and possibly other special operations Specified via a corresponding selector switch will give. In generator-supported operation be an electronic control unit agrees when the genes rator is used to supply energy, what with a start or in any case an increase in performance of the internal combustion engine. This can be particularly the case be particularly the case when a given loading is closed the energy storage was below the level or a be particularly high mileage is required.

In the publication WO 93/07368, in which a Hybrid drive is shown in which the combustion motor mechanically attached to the drive electric motor can be coupled, are possible operating modes of the hybrid drive there explained in detail. In a Start mode is the internal combustion engine switched off, and the electric motor is powered by batteries ben. The drive takes place in an overland operating mode as long with the energy from the batteries as theirs State of charge is above a specified value. There at the internal combustion engine is switched off, or it will optionally at idle speed in standby kept operating. When the battery charge falls below the specified value, the Ver internal combustion engine by a conventional engine control in the required state of increased power output performed, after which he mechanically connected to the drive electronics engine is coupled and thus the vehicle drive takes over. The drive works at the same time electric motor in this case as a generator for charging that of the batteries. Furthermore, there is a burn engine mode provided in which the vehicle is continuously driven by the internal combustion engine.

Another generic method for loading Drive of a series hybrid drive is in the disclosure publication DE 41 33 014 A1 discloses. If requested egg ner increased power output of the drive through ent speaking actuation of the accelerator pedal is there Internal combustion engine from a lower state Increase power output to the required condition ter output along an optimal consumption Characteristic curve raised, preferably at the same time the coupled generator is relieved  is stopped by feeding the drive electric motors done entirely by the generator, but entirely or is partially taken over by the energy store. Also with the This system is the internal combustion engine by means of an ordinary Chen engine control started up.

For increasing the power output of the internal combustion engine with A conventional engine control system takes a certain amount of time needed during which the engine control unit the power request registered and converted into an internal combustion engine start and / or brings the internal combustion engine to the increased target speed who can provide the required additional service. This Duration can be in generator-supported operation of the series hy are disruptive to the drive.

The invention is a technical problem of providing green a method for operating a series hybrid drive de, where the said lagging problems in performance Development of the generator coupled to the internal combustion engine are diminished.

This problem is solved by a method with the characteristics of Claim 1 solved. By using additional speed increasing means in addition to the usual engine control measures the internal combustion engine can comparatively quickly match that of the engine increased output corresponding target speed are, so that accordingly the generator comparatively It quickly provides the required, increased performance likes, if the internal combustion engine was previously switched off or at least in a state of lower power output. This In a first operating variant, means include the measure, the combustion engine in generator-assisted operation of the series hybrid drive not always to be switched off completely, but to keep them in constant operational readiness, whereby the operating point of the internal combustion engine is advantageously dependent is selected from the state of charge of the energy store.

In an advantageous embodiment of the invention according to claim 2 includes the use of additional speed-increasing Means in a further, second operating variant with an internal combustion engine previously switched off an electric one The same is supported by a corresponding star termotor not only up to the normal starting speed, but up to  to an engine speed above that, as desired can be equal to the new target speed or a predefinable one Dimension is below the same. In addition, according to claim 3 the measure should be a temporary burden on the ener giespeicher up to its theoretical maximum power rend the electrical high-speed support for the cremation approved motor.

In a further embodiment of the invention, the use includes additional speed-increasing means according to claim 4 to lead to fuel in the initially stopped burns motor during starting before it is reached the normal starting speed, so that the internal combustion engine quickly can be started under full load.

To quickly reach the target speed through the combustion motor when requesting an increased power output is the further an embodiment of the invention according to claim 5 stig, in which the drive then acting as a generator electric motor additional energy to start the combustion motors provides that depend on the kinetic vehicle energy is branched. This measure is particularly prevalent in situations some where the energy storage is not particularly high Power can be taken.

A preferred embodiment of the invention is as follows described with reference to the drawings, in which:  

Fig. 1 is a schematic plan view of an operating range selector switch for a series hybrid drive a motor vehicle and

Fig. 2 is a perspective view of an automatic transmission selector lever device of the motor vehicle.

The measures described below relate hen on the operation of a in a motor vehicle built-in series hybrid drive, its construction is of a natural nature and therefore no closer here Presentation and explanation required. With such a Series hybrid drives become one or more drives electric motors optionally only from one energy source A traction battery is an example here adopted, or supported by a generator, which is driven by an internal combustion engine, ge feeds.

With the selector switch ( 1 ) shown in Fig. 1, the driver sets the operating mode of the series hybrid drive. In the shown position of the operating range selector switch ( 1 ), the battery operation of the series hybrid drive is set, as symbolized by an associated text display ( 2 ) “battery”, which means that the drive motor or motors are fed solely by the energy of the traction battery. As a special function of this, a release of the charge emergency reserve of the traction battery is provided by actuating an assigned pressure switch ( 10 ), to which an obvious text display ( 7 ) "reserve" is assigned.

In a position symbolized by a written display ( 3 ) "generator" of the operating range selector switch ( 1 ), generator-assisted operation is specified which is mainly of interest in the present case and which will be discussed in more detail below. With two pressure switch functions ( 11 , 12 ), a battery charging mode, symbolized by a text display ( 5 ) "battery charging", or a battery discharge, symbolized by a text display ( 6 ) "empty battery", can be set, these two Switch functions can not be operated at the same time because of their contradicting functions, which is realized for example by a common Wippschaltele element for these two functions ( 11 , 12 ). For these two operating modes, limit values that determine the maximum degree of charging and / or discharging can be defined and changed, ie made dependent on parameters, by means of a separate input device (not shown). The same is also possible for the charging and discharging currents and, if applicable, for other sizes dependent on the driving company.

In a position of the operating range selector switch ( 1 ) symbolized by a text display ( 4 ) "stand charging", the traction battery is charged with the ignition key removed. As a safeguard against unintentional setting of this mode, it is provided that its activation is only possible as long as the ignition is still switched on. The start and end of a idle charge can be set via a timer not shown, so that the associated noise of the internal combustion engine does not occur at undesirable times. As special modes of operation, a full charge can be symbolized by a pushbutton ( 13 ), symbolized by the font display ( 8 ) "fully", or by a further pushbutton ( 14 ) a charge after deep discharge, symbolized by the font display ( 9 ) "for low load "can be set. Analogous to the two special modes of operation of the switch functions ( 11 , 12 ) in generator-assisted operation, charge target values can be specified via separate input devices.

In a further position of the operating range selector switch ( 1 ) symbolized by a text display ( 15 ) "emergency battery operation", an emergency operation takes place using only the traction battery to power the drive. Analogously, in a further position of the operating range selector switch ( 1 ), which is symbolized by a text display ( 16 ) "emergency operation combustion engine", an emergency operation in which the internal combustion engine alone supplies the drive energy. In both emergency operating positions, all higher control functions are overridden. It should only be possible to continue driving under restricted conditions. The associated drive control unit determines which remaining drive control functions are still active.

Below is a closer look at the procedure for Operation of the series hybrid drive in the generator sub supported operation. In this mode be is the electronic drive control unit correct when the Generator for the supply of the drive electric or motors is switched on. This can e.g. B. be the case if a given state of charge of the traction battery terie below or a particularly high driving license is requested. In a first variant of the generator-assisted operation is combustion motor in the periods with not switched on Generator turned off and is used to connect the Ge nerators started. As soon as the provision of additional cher driving power by the internal combustion engine is requested, the control unit starts first hand the speed of movement of an existing one accelerator pedal and / or via an existing kick down switch fixed how big the driver request for is a rapid, increased power delivery. Then become one or more depending on the situation of the following measures taken, which otherwise conditions require a corresponding motor protection function control the delivery of a maximum Allows engine power by, for example, being determined is that the cooling water is warm and an associated Catalyst is preheated.

In the event of a spontaneous request for benefits the previously switched off internal combustion engine started, not only from an associated starter motor dragged to normal start speed and then is supplied with fuel, but rather the elek tric high-speed support by the starter motor is continued up to a higher speed, which up to to the target speed of the desired power output can hen. As a further measure, a lower speed than the normal starting speed start supplying fuel, so  that then the internal combustion engine under full load high turns. In addition, a load can be provided the traction battery to its theoretical lei maximum during the start-up phase allow porous. Because this period is typically barely longer than about a second, this has no negative effects on the battery.

As a further measure, the internal combustion engine can quickly bring to the required target speed provided for a kick-down switch actuation be that the or the electric drive motors in a vehicle braking generator function reversed to be burned in this way to the increased target speed even faster drive. For this purpose, the electrical or electrical Design drive motors appropriately and fit them the electrical control circuit to provide like this is state of the art in itself. Since this measure under Circumstances can impair driving comfort, it is only approved by the control unit if the Traction battery is already heavily discharged or even does not cooperate or only works with partial performance, e.g. B. in one corresponding emergency or gentle operation.

In a further variant of generator-assisted operation, the internal combustion engine is not completely switched off in the periods with the generator not connected to the drive energy supply, but is kept in standby mode in an idle operating state. The driver can switch between the two operating variants of generator-supported operation by means of a switch ( 23 ), which is located in the position shown in FIG. 2 at an ergonomically easy-to-reach location on the selector lever ( 21 ) of an automatic transmission setting unit ( 22 ). In one position of the switch ( 23 ) the internal combustion engine runs continuously, the function of the switch ( 23 ) being of course inactive if an operating mode is selected via the operating range selector switch ( 1 ), in which the operation of the internal combustion engine is excluded. The drive control unit determines the speed and the engine load of the internal combustion engine in the ready position. In principle, there are also several operating cases with this variant, which are either completely independently controlled by the drive control unit or via which a special operating mode can be set, e.g. B. recharging the battery while driving, additionally influenced who can. Normally, when the generator is not supposed to recharge the traction battery, the internal combustion engine runs at low speed and high engine load, taking efficiency and operational readiness into account. If an additional power is suddenly requested from the internal combustion engine, the measures described above for the variant with the internal combustion engine switched off in the meantime can be taken to adapt the engine speed to the new target speed with appropriate transmission in this case. In the event that a useful braking of the traction drive is carried out and / or the traction battery, for example due to its state of charge, no longer takes on, the internal combustion engine can continue to be operated at a low speed, but then the engine load is reduced via a corresponding throttle valve adjustment .

If the automatic transmission selector lever ( 21 ) is brought into the selector lever position "B", see FIG. 2, an increased electric motor braking torque is specified when the accelerator pedal is released. In the selector lever position "B" in pure battery operation, ie in the position of the operating range selector switch ( 1 ) shown in FIG. 1, only the assignment of the accelerator pedal position to the electric motor braking torque is changed. When the generator-supported operation is set, on the other hand, the drive control unit can also use the generator and thus also the internal combustion engine to record the braking torque. This is particularly useful if the traction battery can no longer take up feedback from the drive electric motor, which in this case acts as a generator. If the switch ( 23 ) for continuous operation of the internal combustion engine is operated in the standby state, the internal combustion engine also runs in the vehicle brake operation given the position “B” of the automatic transmission selector lever ( 21 ) and can in this case reduce the fuel consumption in one Go overrun fuel cutoff operation, whereby the throttle valve can also be opened depending on the operating parameters.

Is the internal combustion engine already in the Battery recharging at higher speed and vol Operated engine load on a best consumption characteristic ben, the control algorithms and - Mechanisms to adapt the engine speed to the new target speed less pronounced than in the other ren, the above case applied. In particular can an electrical high-speed support of the Ver internal combustion engine above a certain reason speed and engine load position in the previous Motor operation is eliminated. If the drive control unit notes that the driver is constantly a dynamic driving wise, the base speed of burning can who is in standby mode the. For efficiency reasons, this is done under Consideration of the best consumption characteristic possible always with a high engine load.

Optionally provided, via the associated switch ter controllable special functions do not change the above-mentioned control functions and measures, but only change the constants of target functions, for example with regard to the state of charge in the functions "recharge the battery while driving" and "empty the battery until to destination ". Referring to FIG. 1, the operation switch are such Son of the functions in optical operative connection with the setting position of the operating range selector switch (1) is arranged, which ensures a good overview of the dependent on the respective operating areas of special functions.

Claims (6)

1. A method for operating a series hybrid drive, which includes an internal combustion engine with a mechanically coupled generator, a drive motor that can be electrically coupled to the generator, and an energy store that can be coupled to the generator and the drive electric motor, in which

• - In an operating mode in which the operation of the internal combustion engine is permitted, the internal combustion engine is guided into an operating state of increased power output when an increased drive power is requested,

characterized in that

• - For guiding the internal combustion engine in the operating state he increased power output in addition to a corresponding throttle valve, fuel / air mixture and / or ignition timing adjustment, additional speed-increasing means for rapidly reaching the desired speed are used, which in a first operating variant, in which the internal combustion engine is not completely switched off in the periods with the generator not connected to the drive energy supply, the setting of continuous internal combustion engine operation with an internal combustion engine operating point dependent on the state of charge of the energy store.

2. The method of claim 1, further characterized in that the use of additional speed-increasing means an elec tric revving support for the internal combustion engine Starting the same by a separate starter motor over the normal Starting speed includes in a further, second operating variant, in which the internal combustion engine in the periods with the generator connected to the drive power supply beforehand is turned off. 3. The method of claim 2, further characterized in that the use of additional speed-increasing means in the second operating variant, the approval a temporary load on the energy storage until its includes theoretical maximum power.   4. The method of claim 2 or 3, further characterized in that the use of additional speed-increasing means in the second operating variant, the feeding of fuel in the internal combustion engine when starting it before the normal start speed is reached. 5. The method according to any one of claims 1 to 4, further characterized in that the use of additional speed-increasing means an elec tric high-speed support of the internal combustion engine under Ver including the drive electric motor in generator function tet. 6. The method according to any one of claims 1 to 5, further characterized in that the use of additional speed-increasing means in the first operating variant len continuous combustion engine operation at low low engine speed and high engine load if the Energy storage is required, or at a higher speed and full engine load if the energy storage is charged is required.