DE102017211248A1 - Method for recuperation of kinetic energy of a hybrid vehicle, and control device therefor - Google Patents

Abstract

The invention relates to a method for recuperation of kinetic energy of a hybrid vehicle (10), which has an internal combustion engine (12), an electrical machine (14) and a vehicle electrical system (16) with an energy store (18) which is in a recuperation operation of the hybrid vehicle (12). 10) of the electric machine (14) can be charged with electrical energy, wherein a Rekuperationsstärke (Mrek) of the electric machine (14) in dependence on a current state of charge of the energy storage device (18) and / or a current vehicle electrical system load is set. In order to avoid a more or less uncontrolled vehicle deceleration during recuperation operation, the internal combustion engine (12) is operated to generate a drive torque (Mbkm) in recuperation operation when a recuperation rate (Mrek) exceeds a predetermined recuperation threshold (Mrek0 (B1)). Furthermore, a control device for controlling such recuperation is proposed.

Description

The present invention relates to a method for recuperation of kinetic energy of a hybrid vehicle according to the preamble of claim 1 and a control device for controlling such Rekuperation according to the preamble of claim 7. Furthermore, the invention relates to a equipped with such a control device hybrid vehicle and a for performing a computer program product designed in such recuperation method.

Such a method, such a control device and such a hybrid vehicle, for example, from the patent publication DE 10 2015 006 454 A1 known. The hybrid vehicle known therefrom has an internal combustion engine, an electrical machine and an on-board network with an energy store, which can be charged with electrical energy by the electric machine in a recuperation operation of the hybrid vehicle.

The Rekuperationsbetrieb is used to recover advantageous in the deceleration phases of the vehicle kinetic energy of the vehicle. The electric machine is operated here as an electric generator and generates in this generator mode acting in the sense of a deceleration of the vehicle torque (torque) in a drive train of the vehicle.

From the aforementioned DE 10 2015 006 454 A1 In this case, it is also known to set a recuperation power of the electric machine in recuperation operation, ie its electrical power supplied in the generator mode, as a function of a current charge state of the energy store. If the state of charge is less than or equal to a threshold, a relatively large recuperation power is set, and if the state of charge is greater than the threshold, a relatively small recuperation power is set.

Since the state of charge of the energy storage is influenced by many circumstances of a "previous driving profile" and thus subject to variations in practice, has an adjustment of the recuperation depending on the state of charge of the energy storage z. B. from the perspective of a driver of the vehicle the disadvantage of varying in recuperation operation from case to case vehicle behavior (varying vehicle deceleration), which is often perceived as disturbing especially in a "driver-passive state". How much the vehicle decelerates in recuperation, then depends not only on a current "braking demand", z. As a degree of braking operation by the driver, but also from the previous driving profile.

The term "driver-passive state" is intended in the context of the invention to denote that state of a vehicle controlled by a driver, in which the driver neither actively activates an acceleration nor actively decelerates the vehicle, ie, for example. B. neither an "accelerator pedal" nor a "brake pedal" operated (or similar, provided for speeding up and decelerating operator actions makes).

In contrast, the term "active brake state" in the context of the invention to denote that state of a vehicle in which a deceleration of the vehicle is actively controlled, ie z. B. a driver operates the brake pedal.

The explained disadvantage of the prior art, ie a more or less "varying vehicle deceleration in recuperation", arises regardless of whether in addition to the recuperation of the electric machine in addition to the vehicle also decelerating "drag torque" of the internal combustion engine is effective or not in Rekuperationsbetrieb ,

For example, in a so-called mild hybrid as a possible embodiment of a parallel hybrid electric machine is usually always coupled to the internal combustion engine (unlike a so-called full hybrid with a clutch between the engine and electric machine, which recuperation without entrainment of the internal combustion engine allows). As a result, the cumulative torque of the electric machine and the internal combustion engine always acts in such a mild hybrid in recuperation mode, with further retarding torques in the drive train being able to take effect in the case of auxiliary devices (eg air conditioning devices, etc.) driven mechanically by the internal combustion engine.

It is an object of the present invention, in a hybrid vehicle of the type mentioned in Rekuperationsbetrieb regardless of the previous driving profile to allow a better reproducible vehicle deceleration, in particular z. For example, when decelerating by recuperation without brake operation (eg in the "driver-passive state").

This object is achieved according to a first aspect of the invention in a method for recuperation of the type mentioned in that in recuperation in the presence of a recuperation threshold exceeding a recuperation the Internal combustion engine is operated to generate a driving torque.

The term "Rekuperationsstärke" (the electric machine) is to be understood in the context of the invention wide and z. B. refer to the supplied in the recuperation of the electric machine electrical power, or z. As the recuperation of the electric machine generated by the delaying moment in the drive train (Rekuperationsmoment).

Thus, in the case of an exceptional (defined by the recuperation threshold) high recuperation intensity, the invention results in a superimposition of the resulting deceleration moment (recuperation moment) with the drive torque of the internal combustion engine provided according to the invention.

Depending on the specific setting of the drive torque of the internal combustion engine, it is thus possible, in particular, to effect a substantially constant deceleration of the vehicle, regardless of a preceding driving profile in the recuperation mode.

The dependence of the recuperation intensity on a current state of charge of the energy store (eg having a lithium-ion accumulator, "supercap" accumulator, or the like) and / or a current vehicle electrical system load connected and operated by electrical consumers advantageously takes into account the circumstance Bill that it may be necessary for reasons of energy management, such as at relatively low state of charge of the energy storage or relatively high electrical system load to set a greater Rekuperationsstärke the electric machine in recuperation to ensure the supply of electrical loads from the electrical system and z. B. to avoid excessive discharge of the energy storage.

As regards the dependence of the recuperation intensity of the electric machine to be set on the current state of charge of the energy store, according to one embodiment it is provided that the energy store is monitored continuously in the recuperation mode and an increased recuperation intensity is set when a state of charge below a predetermined charge state threshold is detected (as in the case exceeding the state of charge threshold).

In one embodiment, it is provided that in recuperation operation, the recuperation intensity is also set as a function of a current desired braking amount.

Such a dependency on a current braking request amount, z. B. a current Bremsbetätigungsausmaß by an operating action of a driver (eg., Brake pedal position), advantageously takes into account the fact that the recuperation should be carried out the stronger, the more the vehicle is to be braked.

It is advantageous if an entire current braking torque request can be met solely by the recuperation torque (and possibly additionally acting torque of the internal combustion engine), ie without energy loss by using a conventional dissipative brake system (eg hydraulically acting brake system with "disc brake"). "Drum brake" etc.). If the braking torque request can not be fulfilled due to its large extent, the generation of the required braking torque can be divided between a conventional dissipative braking system and the electric machine operated in the generator mode.

In the invention, by means of the dependency of the recuperation intensity (eg recuperation moment) on the current desired braking amount (eg brake application amount such as brake pedal position), a non-zero recuperation intensity is also preferred in the already mentioned driver-passive state Provided in which a driver neither actively a braking request nor actively enters an acceleration request to effect in this state, a gradual deceleration of the vehicle.

In one embodiment of the invention it is provided that the recuperation threshold is predetermined as a function of a current desired braking amount.

This can advantageously be taken into account the fact that the recuperation should be carried out all the more, the stronger the vehicle is to be braked, and that in this case z. B. a because of a low state of charge of the energy storage and / or a high electrical system load "over a normal extent increased Rekuperationsstärke" only a drive torque of the engine should be "opposed" if without this drive torque the total resulting braking torque (and consequently the vehicle deceleration) in terms would be too big on a current request for braking.

In one embodiment of the invention, the method is carried out in a parallel hybrid vehicle, for example a mild hybrid vehicle, in which the electric machine is always coupled to the internal combustion engine, so that always a cumulative torque of these two devices acts on the relevant powertrain of the hybrid vehicle.

In one variant, the method is performed in a full hybrid vehicle, in which the electric machine and the internal combustion engine are arranged to act on the same powertrain of the hybrid vehicle (parallel hybrid), but with a controllable disconnect clutch between the electric machine and the internal combustion engine is arranged On the other hand, in the context of the invention in the recuperation of the hybrid vehicle this disconnect coupling, if necessary, d. H. in the presence of a recuperation of the electric machine exceeding the predetermined Rekuperationsschwelle, is closed in order to operate the internal combustion engine for generating a force acting on the respective drive train drive torque can.

Although the method according to the invention, as mentioned, can be advantageously used, in particular in a parallel hybrid vehicle, the invention can basically be used for a multiplicity of completely different hybrid concepts. What is essential is the possibility that by means of the electric machine in the generator mode a moment retarding the vehicle and at the same time by means of the internal combustion engine a moment driving the vehicle can be effected. For example only, it should be noted that this also z. For example, in a hybrid concept, the electric machine and the engine operate on powertrains different from each other (eg, each one of a plurality of axles of the vehicle provided with respective vehicle wheels).

In a preferred embodiment of the invention, the method is performed at least in the mentioned "driver-passive state". In this state, variations of the vehicle behavior z. B. for a driver "particularly noticeable" (in contrast to states in which an active braking is controlled).

In a preferred embodiment, the method is (also) carried out in the recuperation mode with a non-zero desired braking amount (eg extent of a brake application, eg brake pedal position), namely at least at a braking request amount below a predetermined braking request extent threshold. This is of practical relevance, in particular in the case of a relatively small desired amount of braking, since, in the case of a particularly large amount of braking demand, a high contribution of the recuperation torque in decelerating the vehicle is desirable anyway.

In contrast, in particular in the case of an extremely large (eg maximum possible) demand for deceleration, it is generally not sensible to operate the internal combustion engine in recuperation operation to generate a drive power because this would be detrimental to a correspondingly strong vehicle deceleration and in any case "maximally recuperates" in this extreme case "Can and should be.

With this embodiment can advantageously also in recuperation with non-zero braking request amount, z. B. from zero different brake actuation amount, regardless of the previous driving profile a particular, in particular constant (that is, possibly still depending on the braking request amount) delay torque can be accomplished.

In view of the fact that in the invention, the recuperation of the electric machine is adjustable depending on the current state of charge of the energy storage and / or the current electrical system load (current electrical power consumption of electrical consumers connected to the electrical system), can be made even to even out the vehicle deceleration (independent of the previous driving profile) be provided, for example, that the drive torque of the internal combustion engine is set in recuperation depending on the current state of charge of the energy storage and / or the current electrical system load.

Alternatively or additionally, it can be provided that the drive torque of the internal combustion engine is set in the recuperation operation as a function of the set recuperation intensity of the electric machine.

In particular, with the two last-mentioned embodiments can advantageously comparatively easily implement an embodiment in which the drive torque of the internal combustion engine is set in recuperation so that a delay torque variation is at least partially compensated, which from the dependence of the recuperation of the electric machine of the current state of charge the energy storage and / or the current electrical system load results.

In particular, z. B. a complete compensation are sought, which can be accomplished, for example, that in the recuperation a setpoint for the adjusted drive torque of the engine is determined as the difference between the set according to the set Rekuperationsstärke the electrical Machine resulting Rekuperationsmoment and a set for a "normal case" normal case Rekuperationsmoment.

Such z. B. continuously determined setpoint for the drive torque of the internal combustion engine can be used by an internal combustion engine controlling device to control relevant actuators of the engine in a suitable manner to regulate the drive torque of the internal combustion engine to the desired value.

As a "normal case" can z. For example, a state may be considered in which the state of charge of the energy store exceeds a predetermined (eg, predetermined) state of charge threshold, or z. B. a state in which both the state of charge of the energy storage exceeds a predetermined state of charge threshold and the vehicle electrical system load falls below a predetermined (eg., Permanently prescribed) on-board network load threshold. In a further development, it is provided that the aforementioned charge state threshold is predetermined as a function of the current vehicle electrical system load.

As far as the normal case recuperation torque present for the "normal case" is concerned, this can be done within the scope of the invention (and depending on the specific hybrid concept, eg parallel hybrid or other concept) e.g. B. as constant or z. B. at most be determined by a braking request amount dependent.

When using a hybrid system, which provides for a so-called fuel cut of the internal combustion engine at the beginning of a recuperation operation in the mentioned normal case, the invention can be realized by providing an on-demand prohibition of fuel cut, so that the internal combustion engine in the recuperation of kinetic energy of the vehicle continue to be fired can.

The control of the internal combustion engine and the electric machine can in this case take place in the recuperation according to the invention such that the sum of the emitted torque at least approximately corresponds to the summation torque in the normal case with fuel cut, so that the same vehicle deceleration results as in the normal case with fuel cut. The indexed drive torque of the internal combustion engine from the combustion therefore preferably corresponds to the increase of the recuperation torque of the electric machine compared to the normal case.

If, in the normal case, the internal combustion engine is "dragged along" in the recuperation mode (ie, the drag torque is added to the recuperation torque of the electric machine, then the optionally generated drive torque of the internal combustion engine is in the recuperation mode according to a development of the invention set to a value that depends on the current speed of the engine (also). This dependence on the rotational speed takes into account the fact that in recuperation operation normally a speed-dependent drag torque of the internal combustion engine acts in the sense of a deceleration of the vehicle in the drive train. This drag torque can be taken into account when it comes to the driver a z. B. substantially only dependent on the brake pedal position to deliver vehicle deceleration. A well-defined dependency of the vehicle deceleration on the brake pedal position can be realized by the control program taking into account the possibly acting drag torque of the internal combustion engine by adjusting the recuperation torque to be additionally supplied by the electric machine.

A setpoint for the recuperation torque (or a differently defined recuperation intensity) can, for. B. depending on the speed of the engine and the state of charge of the energy storage map-based.

With decreasing state of charge, a (tendentially) greater recuperation torque can be applied, so that the state of charge for constant conditions (vehicle electrical system load, engine speed) stabilizes at a specific value.

Alternatively, the setpoint for the Rekuperationsmoment z. B. model-based depending on the speed of the internal combustion engine and the vehicle electrical system load. The model in question can take into account other parameters that affect the efficiency or other properties of the electrical machine, such. B. a voltage applied to the electrical machine operating voltage. The electrical system load can z. B. can be determined as the sum of the modeled power requirements of multiple electrical consumers. For the latter determination may optionally z. B. a power of a DC / DC converter are used, the electrical energy from a first on-board power supply of higher voltage (eg., 48 V or more) in a second on-board power supply of a lower voltage (eg 12 V on-board power supply) transferred.

If it is determined during the recuperation, that again the "normal case" exists, so z. B. the state of charge of the considered energy storage again exceeds a certain state of charge threshold, so the overrun fuel cut of the internal combustion engine (in still non-existing acceleration request) again be allowed, so that then the further recuperation takes place again (as in the prior art) with uncontrolled engine.

In a particular embodiment, the prohibition of overrun fuel cutoff in the recuperation operation takes place only if the recuperation torque set for its state (characterized, for example, by the state of charge of the energy store, vehicle electrical system load, engine speed, desired braking amount) in accordance with the invention is the recuperation torque that normally results exceeds a minimum amount. This minimum amount can z. B. be in the range of 0.5 times to 1.5 times the normally resulting drag torque of the internal combustion engine (to avoid "overcompensation" of increased recuperation). However, as an alternative or in addition, avoidance of such "overcompensation" can also be achieved by compensating for the "sudden omission of the drag torque" as required by the invention by setting the recuperation intensity of the electric machine in such a way that is taken into account (and without any problems) becomes.

The recuperation strategy described can be used for driver-passive recuperation (in the driving state without brake and accelerator pedal actuation) and / or for active-brake recuperation (in the driving state with brake pedal actuation). It is particularly advantageous in the case of driver-passive recuperation, since only low Rekuperationsmomente may be applied (possibly zero moment), while during recuperation during braking often high Rekuperationsmomente be applied (especially in strong brake pedal actuation), for an electrical energy supply anyway are sufficiently large.

The invention is primarily applicable to mild hybrid systems. In a modification, it is also applicable to full hybrid systems in which the recuperation can normally be done with open disconnect clutch. If in this case, however, a significantly increased recuperation intensity is set in accordance with the invention (eg, required for energy storage charging and / or sufficient consumer power supply), the disconnect clutch is closed in order to allow compensation of the increased recuperation torque by the internal combustion engine. In this case, the drive torque of the internal combustion engine should compensate not only the additional generator torque (recuperation torque of the electric machine), but also the loss torque of the internal combustion engine, which is not effective in the normal recuperation.

According to a further aspect of the invention, the object stated in the introduction is achieved in a control device of the type mentioned above in that the control device is also designed to operate the internal combustion engine to generate a drive torque in recuperation operation when a recuperation intensity exceeds a predetermined recuperation threshold.

The control device may in particular be a "hybrid control device" which, according to a predetermined hybrid operating strategy based on operating parameters entered therefor (eg brake request amount such as brake pedal position, charge state of the energy store, vehicle electrical system load, etc.), the internal combustion engine and the electrical Actuates the machine accordingly.

The particular embodiments and design details described here for the recuperation method according to the invention can also be provided in an analogous manner as embodiments or special design details of the control device according to the invention.

According to a further aspect of the invention, a hybrid vehicle is proposed which is equipped with means for carrying out the recuperation method described, for example comprising a control device designed to carry out the described recuperation method.

Finally, the invention proposes a computer program product comprising a program code which carries out a recuperation method of the type described here on a data processing device (for example hybrid control device of the vehicle).

• 1 ein Ablaufdiagramm eines Verfahrens zur Rekuperation gemäß eines Ausführungsbeispiels,
• 2 eine schematische Darstellung eines Hybridfahrzeuges, das mit einer Steuereinrichtung zur Durchführung des in 1 dargestellten Rekuperationsverfahrens ausgebildet ist,
• 3 eine beispielhafte Auftragung eines gemäß einer Hybridbetriebsstrategie vorgesehenen Rekuperationsmoments einer in dem Fahrzeug von 2 eingesetzten elektrischen Maschine in Abhängigkeit von dem Ausmaß eines Beschleunigungs- bzw. Verzögerungswunsches des Fahrers, und
• 4 eine Auftragung eines im Rekuperationsbetrieb des Fahrzeuges von 2 gemäß der Hybridbetriebsstrategie von einer Brennkraftmaschine erzeugten Antriebsmoments.

The invention will be further described by means of embodiments with reference to the accompanying drawings. They show:

• 1 a flowchart of a method for recuperation according to an embodiment,
• 2 a schematic representation of a hybrid vehicle, with a control device for performing the in 1 formed recuperation method is formed,
• 3 an exemplary plot of a provided according to a hybrid operating strategy Rekuperationsmoments one in the vehicle of 2 used electric machine depending on the extent of an acceleration or deceleration request of the driver, and
• 4 a plot of a in Rekuperationsbetrieb the vehicle of 2 Drive torque generated by an internal combustion engine according to the hybrid operation strategy.

1 shows a flowchart of a method for recuperation of kinetic energy of a hybrid vehicle having an internal combustion engine, an electric machine and a vehicle electrical system with an energy storage, which is chargeable in the recuperation of the hybrid vehicle from the electric machine with electrical energy.

In the present exemplary embodiment, the method is started when, in the presence of a speed of the hybrid vehicle (eg, greater than 10 km / h) that is above a predetermined threshold, a "driver-passive state" or "braking request" is detected, and therefore the Hybrid vehicle should be delayed.

The process begins with a step S1 in which a current "brake actuation amount" is detected as a current "brake request amount" (quantitative measure of the desired deceleration).

In the present example, as a brake operation amount z. B. the position of one of a driver of the vehicle to be operated brake pedal used. Alternatively, z. B. another, directly determined from the detected brake pedal position measure can be used, if necessary, taking into account a time course of this brake pedal position.

In a subsequent step S2 a current state of charge of the energy storage is detected, wherein z. B. in the case of common electrical energy storage such. As lithium-ion batteries, nickel-metal hydride batteries in the art various methods for determining a so-called "State of charge" (SOC) are known, which can be used here in the context of the invention advantageously to a the Charge state quantifying measure to capture.

In a subsequent step S3 a current on-board network load is detected, which here is to be understood as the sum of those current loads (eg electrical services) which result from a current energization of electrical consumers connected to the electrical system (eg air-conditioning devices, lighting devices, etc.).

In a subsequent step S4 is a "Rekuperationsstärke" a Rekuperationsmoment the electric machine as a function of that in step S1 detected brake application amount, the in step S2 recorded state of charge and in step S3 recorded on-board network load.

Within the scope of the invention, and thus also in the illustrated example, the setting of the recuperation moment (or alternatively of a differently defined "recuperation level") is composed as an additive of two portions, namely a first "normal case portion" and a second (optionally in case of need fixed percentage), the normal portion being based on the (in step S1 detected) and increases with increasing brake operation amount (An example of such a specification is in 3 shown), and wherein the additive portion based on the (in step S2 detected) state of charge of the energy store and / or the (in step S3 recorded) on-board network load.

The additional component is set to zero at least at a charge state of the energy store exceeding a predetermined charge state threshold.

However, the decision as to whether or not to set the additive proportion to zero may also be based on a more complex criterion check, which is preferably checked on the basis of the determined values of the state of charge and the on-board network load.

If, after checking the said criterion, a determination of a non-zero additional proportion is made, the size of this additional proportion is also determined, again preferably as a function of (at least) the state of charge of the energy store and / or the on-board network load, wherein preferably the additional proportion tends to increase with decreasing state of charge and tends to be greater with increasing vehicle electrical system load. In a very simple embodiment of the invention in this regard, but the additional share could also z. B. be selected with a fixed predetermined value.

The additional portion can be advantageously used to improve the energy management in the hybrid vehicle and in particular to avoid excessive discharge of the energy storage.

On the other hand, this additional share is a cause of a not well reproducible vehicle behavior in recuperation, which z. B. can be perceived by a driver as rather unusual or disturbing. Especially in the recuperation with relatively large Rekuperationsstärke due to currently relatively heavily discharged energy storage, it can be one for the driver unusual delay of vehicle movement come.

In a subsequent step S5 is checked if that in the step S4 set regenerative torque exceeds a predetermined Rekuperationsschwelle, and if so, the internal combustion engine for generating a force acting on a drive train of the hybrid vehicle drive torque operated.

In the present example, the recuperation threshold is identical to the normal case component explained above (predetermined), meaning that the recuperation threshold is always exceeded when in step S4 a non-zero additional percentage is determined.

In step S5 In this case, the drive torque to be supplied by the internal combustion engine is set.

In general, such a drive torque can be set with a value equal to or greater than zero (which therefore does not act in the sense of a deceleration of the vehicle and possibly in the sense of an acceleration of the vehicle in the relevant drive train).

As long as the recuperation operation of the vehicle is maintained, the steps described become S1 to S5 repeated continuously.

Since in the present example, this drive torque of the internal combustion engine identical to that in step S4 fixed additional share (the Rekuperationsmoments the electric machine) is determined, ultimately, particularly advantageous the dependence of the step S4 adjusted Rekuperationsmoments the electric machine from the current state of charge of the energy storage and / or the current vehicle electrical system load compensated.

For the driver of the vehicle, this advantageously means that he "senses" a vehicle behavior in which the accelerations and decelerations of the vehicle depend solely on its current actuations of an accelerator pedal and the brake pedal of the vehicle.

2 shows an embodiment of a hybrid vehicle 10 equipped with a hybrid propulsion system, by means of which in deceleration phases an inventive method for recuperation of kinetic energy of the vehicle 10 can be carried out.

The vehicle 10 has an internal combustion engine 12 (eg gasoline engine, diesel engine or the like), an electric machine 14 and a wiring system 16 with electric accumulators 18 and 20 (Energy storage) on in the recuperation of the vehicle 10 from the (then in generator mode operated) electric machine 14 be charged with electrical energy.

In the example shown, the hybrid drive system according to the concept of a so-called parallel hybrid (here: Mildhybrid) is formed, in which the internal combustion engine 12 and the electric machine 14 always mechanically coupled together in a common drive train of the vehicle 10 are arranged, in the example shown via a coupling 22 , a gearbox (automatic transmission) 24 and a differential gear 26 to two front wheels 28 . 30 of the vehicle 10 leads, whereas rear wheels 32 . 34 of the vehicle 10 not included in a powertrain of the hybrid propulsion system in this example.

The operation of the internal combustion engine 12 and the electric machine 14 is controlled by an electronic program-controlled control device 40 according to a "hybrid operation strategy" defined by a control program based on a plurality of the control means 40 for this purpose supplied signals (eg, sensor signals) "s" controlled. These include z. B. signals (not shown) representative of the positions of an accelerator pedal and a brake pedal of the vehicle 10 , for the individual states of charge of the energy storage 18 . 20 , for the load of the electrical system 16 by electrical consumers connected thereto and for further operating parameters of the vehicle 10 are.

In the example shown, the electric machine 14 formed by a 3-phase AC motor in a controlled manner via a bidirectional AC / DC converter 42 with electric power from the first energy storage 18 (Here: for example, a 48 V lithium-ion battery) can be supplied, so in one (in the example of the control device 40 controlled) inverter mode of the AC / DC converter 42 the electric machine 14 in a drive mode for generating the vehicle 10 driving (or at least not delaying) moments to operate.

The electric machine 14 can in the recuperation mode of the vehicle 10 However, also be operated in a generator mode, what the AC / DC converter 42 , according to the control device 40 driven, operated in rectifier mode to the vehicle 10 to decelerate and thereby kinetic energy of the vehicle 10 in the first energy storage 18 to recuperate.

In the example shown, the electrical system includes 16 a "high voltage part" comprising the AC / DC converter 42 and the first energy storage 18 (With Rated voltage of 48 V), and a "low-voltage part" comprising a unidirectional DC / DC converter 44 and the second energy storage 20 (with nominal voltage of 12 V).

In the example shown, electrical energy can thus be required from the high-voltage part or first energy store 18 over the DC / DC converter 44 to the low-voltage part or second energy storage 20 be transmitted. This functionality as part of an energy management can, for. B. of the illustrated control device 40 or another, specially provided for this control device (not shown) to be accomplished.

That in the controller 40 during operation of the vehicle 10 expiring control program includes a program code that already with reference to 1 described recuperation method when based on the control device 40 supplied signals "s" the desire for a delay of the vehicle 10 (Brake pedal is actuated, "Active-brake state") is detected, or when at above a predetermined speed limit (eg., About 10km / h) lying speed of the vehicle 10 a "driver-passive state" (neither gas nor brake pedal is pressed) is detected.

When the recuperation process of 1 from the controller 40 of the vehicle 10 from 2 is performed, so in step S1 detects the brake operation amount based on the inputted signals "s".

In the steps S2 and S3 is also based on the input signals "s" a state of charge regarding the energy storage 18 . 20 and the on-board network load recorded. The state of charge in the present example is the state of charge measured by means of appropriate sensors (eg "SOC") of the first energy store 18 detected. Alternatively, as the state of charge could also be that of the second energy storage 20 or a combination (eg, weighted average) of the individual states of charge of the two energy stores 18 . 20 be used. With regard to the detection of the on-board network load, it should be noted that in the present example, apart from the electrical machine 14 no further electrical consumers in the 48 V high-voltage part of the vehicle electrical system 16 are connected so that here as on-board network load z. B. the sum of the instantaneous electrical power of the 12 V low-voltage part of the electrical system 16 operated electrical equipment (in 2 not shown) is detected. In practice, the latter detection can often with sufficient accuracy z. B. by detecting the current electrical "conversion power" of the DC / DC converter 44 be accomplished.

If different from the illustrated embodiment, further electrical consumers in the 48 V high-voltage part of the electrical system 16 are connected, these should also be taken into account for determining the on-board network load.

In step S4 the adjustment of the recuperation torque of the electric machine takes place 14 depending on the speed of the internal combustion engine 12 , the position of the brake pedal, the said state of charge and the vehicle electrical system load.

For this purpose, in the control device 40 at least one corresponding characteristic field (eg look-up table) has to be stored.

In step S4 can z. B. first set a "normal case proportion" of Rekuperationsmoments depending on the brake pedal position. The stronger the brake pedal is actuated, the greater (greater or lesser) the normal case proportion is selected. If the brake pedal is not actuated (driver-passive state), a relatively small minimum recuperation torque is set in the illustrated example (which, however, could also be specified as zero).

If in step S4 on the basis of the detected state of charge (and possibly the detected on-board network load) from the control device 40 determined on the basis of a predetermined criterion that the risk of not reliable electrical supply to the on-board network 16 connected electrical loads and / or the risk of excessive discharge of the energy storage 18 exists, so just not the "normal case" is present, then in step S4 still set a non-zero "additional share" for the set recuperation moment.

In step S5 if in step S4 a non-zero additional proportion of Rekuperationsmoments has been determined, the internal combustion engine 12 operated to generate a drive torque acting on the drive train, in such a way that at least this additional component of the recuperation torque is at least approximately compensated with this drive torque.

The steps S4 and S5 will be described again below with reference to the exemplary representations of 3 (to step S4 ) and 4 (to step S5 ) explained.

3 is an exemplary plot of a normal case fraction "Mrek0" of the recuperation torque to be set as a function of a desired braking amount "B" (for B> 0, B can, for example, be regarded as representative of the brake pedal position).

As with the in 3 drawn curve "Mrek0 (B)" is shown in this example assumed that even in the driver-passive state (B = 0), a small recuperation torque from the electric machine 14 to deliver.

With increasing demand for braking demand (here: brake application amount) "B" also the normal case proportion "Mrek0 (B)" of the step increases S4 to be adjusted Rekuperationsmoments. It can, as out 3 can be seen, the case occur that from a certain amount of braking request B no further increase in the Rekuperationsmoments longer possible (depending on the actual performance of the electric machine 14 in generator mode). In addition, increasing braking request B Therefore, it remains at a no longer to be increased Rekuperationsmoment, to fulfill the braking request then z. B , a conventional braking system (eg hydraulic brakes, electromechanical brakes, etc.) are used.

It is assumed by way of example that a current braking request amount " B1 "Establishes a corresponding normal case proportion" Mrek0 (B1) ", and at the same time because of a relatively low state of charge of the energy store 18 and / or a relatively high vehicle electrical system load (eg, sensorically based on operating parameters of the DC / DC converter 44 to detect) the risk of even further discharge of the energy storage 18 consists. In this case, in step S4 a calculated on the basis of a predetermined criterion additive proportion "ΔMrek" set so that set as a sum of normal case share and additional share recuperation "Mrek" by the amount "ΔMrek" on the in 3 Plotted normal case curve "Mrek0 (B)".

The amount ΔMrek is in step S4 z. B. depending on the state of charge of the energy storage 18 and / or the on-board network load.

4 shows a plot of one in the step S5 in dependence on the additional portion "ΔMrek" to be determined drive torque "Mbkm" of the internal combustion engine 12 , In the example shown, Mbkm is selected to be the same as ΔMrek and thus a compensation of the additional deceleration of the vehicle caused by the additional portion ΔMrek (otherwise) 10 accomplished.

In summary, the invention advantageously makes it possible to ensure the electrical supply of the vehicle via the vehicle electrical system without having to accept undesired variations of the vehicle deceleration in recuperation operation. Due to the torque neutrality of the strategy used in the example described, it is advantageously possible, in particular without any disadvantages for the driving behavior, to take measures at an early stage against discharging the energy store too deeply, if a special driving profile requires it. This can reduce the so-called "cycling" (amount of charge and discharge processes) of a battery used as an energy storage device and the resulting aging processes.

LIST OF REFERENCE NUMBERS

10

hybrid vehicle

12

Internal combustion engine

14

electric machine

16

board network

18

energy storage

20

energy storage

22

clutch

24

transmission

26

differential gear

28

front

30

front

32

rear wheel

34

rear wheel

40

control device

42

AC / DC converter

44

DC / DC converter

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

• DE 102015006454 A1 [0002, 0004]

Claims (9)

Method for recuperation of kinetic energy of a hybrid vehicle (10), which has an internal combustion engine (12), an electrical machine (14) and an electrical system (16) with an energy store (18) which is in a recuperation operation of the hybrid vehicle (10) of the electrical machine (14) is chargeable with electrical energy, wherein a Rekuperationsstärke (Mrek) of the electric machine (14) is set in dependence on a current state of charge of the energy storage device (18) and / or a current vehicle electrical system load, characterized in that in the recuperation at If a recuperation intensity (Mrek) exceeds a predetermined recuperation threshold (Mrek0 (B1)), the internal combustion engine (12) is operated to generate a drive torque (Mbkm). Method according to Claim 1 , wherein in Rekuperationsbetrieb the Rekuperationsstärke (Mrek) is further set in dependence on a current braking request amount (B). Method according to one of the preceding claims, wherein the recuperation threshold (Mrek0 (B)) is predetermined as a function of a current desired braking amount (B). Method according to one of the preceding claims, wherein the drive torque (Mbkm) of the internal combustion engine (12) is set in recuperation depending on the current state of charge of the energy storage device (18) and / or the current vehicle electrical system load. Method according to one of the preceding claims, wherein the drive torque (Mbkm) of the internal combustion engine (12) in the recuperation operation in dependence on the set recuperation rate (Mrek) of the electric machine (14) is set. Method according to one of the preceding claims, wherein the drive torque (Mbkm) of the internal combustion engine (12) is set in Rekuperationsbetrieb so that a delay torque variation is at least partially compensated, which from the dependence of the Rekuperationsstärke (Mrek) of the electric machine (14) of the current charge state of the energy storage (18) and / or the current electrical system load results. Control device for controlling a recuperation of kinetic energy of a hybrid vehicle (10), which has an internal combustion engine (12), an electrical machine (14) and a vehicle electrical system (16) with an energy store (18) which is in a recuperation operation of the hybrid vehicle (10). from the electric machine (14) can be charged with electrical energy, wherein the control device is designed to recuperation a Rekuperationsstärke (Mrek) of the electric machine (14) in response to a current state of charge of the energy store (18) and / or a current vehicle electrical system load to set, characterized in that the control device is further configured to operate the internal combustion engine (12) for generating a drive torque (Mbkm) in Rekuperationsbetrieb in the presence of a predetermined recuperation threshold (Mrek0 (B)) exceeding Rekuperationsstärke (Mrek). Hybrid vehicle (10), comprising an internal combustion engine (12), an electrical machine (14) and a vehicle electrical system (16) with an energy store (18), which with a control device according to Claim 7 Is provided. Computer program product comprising a program code executed on a data processing device, a method according to one of Claims 1 to 6 performs.

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