DE4344053A1 - Hybrid-drive vehicle drive control method - Google Patents

Abstract

A method of controlling a hybrid-drive vehicle i.e. a vehicle equipped with a main IC engine (6) and a battery powered electric machine and including separate clutch couplings (3, 5) employs an electrical auxiliary (4) which can be engaged to power the transmission shaft (1) and output gearbox (2) when independently supplied from an accumulator (7) or to operate as a recharging generator. In this latter mode the IC engine (6) provides both vehicle propulsion and generator drive or on a downward incline regenerative braking may temporarily replace the engine (6) for accumulator (7) re-charging.The electric drive is employed for environmentally restricted low speed/low energy running e.g. in town centres followed by main engine running/recharging elsewhere.

Description

The invention relates to a method for operating a hybrid vehicle of the type mentioned in the preamble of claim 1 and an apparatus for performing the method.

Hybrid vehicles in which the vehicle is either al by an internal combustion engine, especially an Otto engine or diesel engine, just by one from a rechargeable electrochemical energy storage (battery) fed and used Recharge the energy storage also as a generator bare electric machine or at the same time by burning Motor and the electric machine are driven in known various variants, u. a. from DE-OS 21 33 485, DE-29 43 554-A1, DE-29 45 303-C2 and DE-31 12 629-C2.

In general, such hybrid vehicles are in a lower Power or speed range and / or in one order field where low emissions are important, e.g. B. in city rides, driven only by the electric machine and in the dar overlying power or speed ranges or at Overland trips generally only from the combustion engine.

It is well known during the combustion engine Operating phases of the hybrid drive on gradients and on Decelerate the vehicle to couple the electric machine - so far it is not always connected anyway - and in the genera  gate operation to control the during these operating phases charge or recharge electrochemical energy storage.

Basically, it is also known (DE-OS 21 33 485) the electric machine - driven by the internal combustion engine - operated as a generator and charge the electrochemical energy store. This Be drive-wise is particularly advantageous viewed because the internal combustion engine then on overland routes should be more evenly loaded, which leads to a substantial ver reduce the exhaust emissions of the internal combustion engine should. Fuel Consumption Considerations There was no fuel optimization for the entire vehicle employed. In the hybrid vehicles operated in this way Incidentally, the performance of the internal combustion engine should be preferred be dimensioned larger than it is for normal overland trips, d. H. without coupled generator, is necessary, so at over if necessary, land journeys regardless of the respective Traction conditions or requirements the energy storage to be able to charge.

In another known hybrid vehicle (DE-29 43 554-A1), due to its special conception, not only a high standard of spontaneity, but also by particularly low fuel consumption, it is also common the electric machine not only on slopes and / or on Deceleration phases of internal combustion engine driving - charging the electrochemical energy store - generator operate, but also when the energy content of the cont carefully monitored electrochemical energy storage during of the electromotive driving operation under a given minimum value drops. In this case, the Ver internal combustion engine switched on automatically and the electric machine out of their motor operation and to charge the Energy storage reversed into generator operation.

This continuous monitoring of the energy content of the elec trochemical energy storage and changing the operating mode ′  is absolutely necessary in this known hybrid vehicle, because the electric machine here - apart from its generator function - not just as a drive machine for the vehicle serves, but in particular also as a starting machine for the internal combustion engine without a flywheel is required and therefore at least it must always be ensured that the as Motor operated electric machine for starting the combustion motors from standstill to the required minimum rotation number of the internal combustion engine can be accelerated.

For hybrid vehicles, which can either be made from an elec trochemical energy storage powered electric motor or by an internal combustion engine, it is for the purpose of ver need optimization particularly important that both engines possible at least in a consumption-based at least comparative manner se favorable performance range are operated, unless in special cases other aspects, e.g. B. the Emission, priority must be given.

It is therefore already known (e.g. DE-31 12 629-C2) for the purpose of ver Optimizing the consumption of the combustion engine of a hybrid vehicle to operate in such a way that in a lower power or Ge speed range only the electrical machine and in one closing upper power or speed range only the internal combustion engine is effective as a prime mover. This Operating procedures are based on the knowledge that the specific Fuel consumption of internal combustion engines, especially of Otto or diesel engines especially in the lower part-load range high and in the upper part load range - close to full load - comparative is cheap and that, in contrast, electrical machines in the sem lower part load range of the hybrid vehicle in particular then work with a comparatively good efficiency if they are comparatively compared to the internal combustion engine small nominal power of z. B. only 10 to 20% of the combustion own motors. In this known hybrid vehicle (DE-31 12 629-C2) is now switching from that operated as a motor Electric machine on the internal combustion engine for further ver need optimization at a performance or speed  value made depending on the expected the distance to be covered by the hybrid vehicle to be covered will change.

Against this background, the object of the invention is now reasons to apply a method for operating a hybrid vehicle ben, with the help of the total consumption of the hybrid vehicle is further optimized.

This task is carried out in a process of Claim 1 mentioned type according to the invention by the Drawing features of claim 1 solved.

Advantageous refinements and developments of the invention are specified in the subclaims.

The invention is described below using an exemplary embodiment explained in more detail.

Show in the drawing

Fig. 1 in hybrid vehicle including an array of internal combustion engine and the electric machine,

Fig. 2 shows the schematic diagram of a control and Re gel means for the hybrid vehicle,

Fig. 3 shows a conventional motor characteristic field of a Burn voltage motors and,

Fig. 4 shows an (unusual) engine consumption map egg nes internal combustion engine.

In the embodiment of FIG. 1, a hybrid vehicle is shown, as it is from its structure, for example from DE-OS 29 43 554 or from the magazine "Gute Fahrt" 1/90, Be te 8 is known. In this hybrid vehicle, the input shaft le 1 of a conventional motor vehicle transmission 2 is connected via a first switchable disconnect clutch 3 to an electric machine 4 which can be operated optionally as an electric motor or as a generator, and via a second switchable disconnect clutch 5 to an internal combustion engine 6 .

The hybrid vehicle can be driven in a known manner as required either by the electric machine 4 operated as an electric motor, the first clutch 3 being closed and the second clutch 5 open, or solely by the internal combustion engine 6 , in which case both clutch 3 and 5 are closed and the electric machine 4, which is neither electromotive nor ge-generator, rotates as a flywheel. In this internal combustion engine operating phase, the electric machine 4 could also be used for driving the hybrid vehicle (e.g. on uphill sections or during special acceleration phases) by connecting it to the electrochemical energy store 7 (drive battery) or in its engine operation is controlled.

Each have an internal combustion engine and an electric machine send hybrid vehicles are u. a. designed to be in a and the same vehicle as required, the specific pre Use parts of an electric motor or an internal combustion engine to be able to B. in special inner-city areas zero emissions and / or low noise of the electromo tors and outside of these areas, e.g. B. for overland trips o. Ä. the assets with the internal combustion engine even longer distance without a refueling stop and if the road conditions allow, if necessary, also at higher speeds to be able to cover.

With the inventive method for operating a hybrid vehicle z. B. the type shown in Fig. 1 is keeping the aforementioned basic operational possibilities and advantages of such a hybrid vehicle, the fuel requirement of the entire vehicle optimized in a previously unfamiliar manner, namely simply that the internal combustion engine 6 in driving phases in which his specific fuel consumption is high, in a special way is additionally charged with generator power for charging the electrochemical energy store (drive battery) 7 on board, so that due to the resulting increase in the torque required of him at one point of his consumption map with the comparison previously decidedly lower specific fuel consumption is operated.

The superimposed generator power N _{L of} the electric machine 4 is controlled in such a way that the total fuel consumption of the internal combustion engine 6 , based on the total distance traveled (without internal combustion engine and with superimposed Ge generator power and electromotive) is lower than the fuel consumption required for the same route at one purely combustion engine (ie without superimposed generator power) operation.

The total fuel consumption is thus composed of the fuel consumption for the propulsion of the hybrid vehicle operated by the internal combustion engine and the fuel consumption for driving the generator-operated electric machine 4 , the electrical energy generated in the process initially stored in the electrochemical energy store 7 and in a later driving phase again for the electromotive propulsion of the Hybrid vehicle is made available.

In cases in which the electrochemical energy store 7 is at least approximately fully charged at this point in time, that is to say, for. B. still has about 70% of its charging capacity, the internal combustion engine 6, on the other hand, is simply switched off and the propulsion of the hybrid vehicle is effected solely by the electric motor 4 , which is then fed from the electrochemical energy store 7 , until the operating circumstances of the Hybrid vehicle have changed so that the internal combustion engine 6 as a sole drive could again be operated in more fuel-efficient higher load areas, or until the electrochemical energy store 7 is discharged to the extent that it is again cheaper to use the hybrid vehicle in the aforementioned manner To drive the internal combustion engine 6 and at the same time recharge the energy store 7 by the generator electric machine 4 .

As far as a hybrid vehicle type is present, in which the electric machine or its rotating part during the combustion engine operation of the hybrid vehicle, notwithstanding FIG. 1, is not always mechanically coupled to the internal combustion engine anyway, it is of course necessary to first mechanically connect the electric machine to the internal combustion engine to couple before it is controlled to charge the electrochemical energy storage in the generator operation.

Ultimately, it is in front by the method according to the invention partially possible to use the fuel so that the Fuel consumption of the hybrid vehicle is lower than at a conventional, i.e. H. operated purely by combustion engine vehicle.

It is understood in this context that the We efficiency chain for electrical energy conversion and electromotive propulsion of the hybrid vehicle of special Meaning is.

In the typical engine map of an internal combustion engine shown as an example in FIG. 3, three medium-pressure characteristics for three different constant engine outputs are shown in broken lines as a function of the speed ne ben of the thick full-load characteristic curve and three thinly drawn hyperbolic torque characteristic curves for three different transmission gears of the hybrid vehicle also shows several lines, each with constant specific fuel consumption. Although this map was of course based on a specific internal combustion engine, apart from the absolute sizes, it applies in principle to all gasoline and diesel engines.

From this engine map it is easy to see that the spec Fish fuel consumption of an internal combustion engine in the bottom  ren part load ranges rises sharply.

For the explanation of the invention it is assumed that a Hy bridfahrzeug about the Golf class is present, which with an Elek electric machine with a nominal output of only about 6 kW is.

If such a hybrid vehicle according to the prevailing operating conditions of the internal combustion engine 6 z. B. at et wa 2000 min ^-1 with a propulsive power N _F of about 6 kW is driven, so in the assumed example it drives at about 50 km / h, then the internal combustion engine 6 operates in a relatively low-load range with a specific low fuel consumption Fuel consumption b _e of approximately 360 g / kWh, as can be seen from the engine map in FIG. 3.

If in this combustion engine driving phase of the hybrid vehicle, the electric machine 4 is controlled according to the invention in its generator operation in order to recharge the electrochemical energy store 7 , then the internal combustion engine 6 instead of the 6 kW power N _F required previously only for the propulsion of the hybrid vehicle a higher total power N _F + N _L , e.g. B. 8 kw demanded, namely the power N _F for the propulsion of the hybrid vehicle and additionally the superimposed generator power N _L for driving the work as a generator, the electric machine 4th For the internal combustion engine 6 , the specific engine consumption N _F + N _L of 8 kW at 2000 min ^-1 results in a specific fuel consumption b _e 'of about 305 g / kWh. In Fig. 3 the corresponding medium pressure curve with a constant engine power of 8 kW is not shown further, but it lies approximately in the lower third between the medium pressure curve for 6 kW and 11 kW.

While there is a fuel consumption per hour of 6 × 360 g / kWh = 2160 g of fuel in the case of the purely internal combustion engine propulsion with the engine power N _F of 6 kW, the fuel consumption of the internal combustion engine 6 is at the same time as the 2 kW generator-operated electric machine 4 is driven per hour a total of 8 × 305 g / kWh = 2440 g fuel. The additional consumption as a result of the 2 kW generator power (charging power N _L ) is therefore 280 g of fuel. The specific generator power consumption, ie the additional consumption per kilowatt hour generated is thus 140 g / kWh.

For the evaluation of the fuel consumption of the entire vehicle, it is of course not only interesting and important what specific fuel consumption must be used to generate a kilowatt hour of generator power, but also how much of it can be used as the drive power for the vehicle in the electromotive operation of the electric machine 4 . The efficiency chain of the electrical function chain, ie the overall efficiency η _tot of electrical energy generation, storage and conversion into drive energy, plays an important role. The following individual efficiencies can be assumed today based on modern components:

A specific generator power consumption according to the above example of e.g. B. 140 g / kWh, ie the specific fuel consumption of the internal combustion engine 6 to generate a kilowatt hour of generator power, thus results in an equivalen th specific fuel consumption of

for the purely electromotive propulsion of the hybrid vehicle, ie when this energy generated in a generator and stored in the energy store 7 is later removed from the energy store 7 again by the electric machine 4 which is operated by an electric motor for the propulsion of the hybrid vehicle.

In order to obtain a positive energy balance, the generator power (charging power N _L ) must be regulated in such a way that the condition

respectively

is fulfilled.

If this condition is not met, the superimposition of regenerative power (N _L ) would lead to a specific fuel consumption for the (later) purely electromotive drive, which is at least as large as for the purely combustion motor drive. In this case, it would not make sense to additionally load the internal combustion engine with generator power; it would then be better to continue driving with the combustion engine in spite of the inherently poor specific fuel consumption.

It is easy to see that for this type of overall consumption optimization of the hybrid vehicle in addition to the choice of the operating point of the internal combustion engine 6 and the choice of the regulated or regulated generator power (charging power N _L ) of the electric machine 4, the efficiency chain, ie the total efficiency degree η _tot is of particular importance. The better the overall efficiency for electrical energy conversion, etc., the more fuel can be saved in this way.

With a hybrid vehicle can thus use certain profi le of the vehicle, if it would have to be operated comparatively frequently in low-load areas of the internal combustion engine 6 , using the operating method according to the invention, even in comparison to purely combustion-powered vehicles, who would save fuel.

The electric machine 4 is preferably regulated in such a way that the superimposed generator power N _{L is} well defined to a value at which the engine 6 loaded with the propulsive power N _F and additionally with the drive of the generator-operated electric machine 4 has a specific fuel consumption b _e 'reached, which is at least in the vicinity of its specific fuel consumption minimum.

This can be achieved with little effort in terms of control technology in that the electric machine 4 is controlled or regulated in such a way that the relationship N _L = K × n -N _{F is} fulfilled, where n is the engine speed and K is the stroke volume H of the internal combustion engine is proportional and determinable with the help of the engine consumption map characteristic characteristic constant of the internal combustion engine 6 .

This is explained in more detail using the map shown in FIG. 4.

4, the effective average combustion pressure P _e as a function of the specific fuel consumption b _{e of} the internal combustion engine is shown in FIG. 4, with different engine speeds n as parameters.

It has been shown that in such a manner of representation se for both petrol and diesel engines regardless of whose number of cylinders is a field of very closely about hyperbolic curves, so that it for the front lying purpose i. a. is sufficient, this characteristic field by ei ne to replace the average hyperbolic curve, the mathema table by the equation

P _e = k × b _e ¹

can be described, in which k and l are each characteristic Are constants for the respective motor type.  

The engine consumption map shown in FIG. 4 has of course been created using a specific internal combustion engine, namely a 6-cylinder gasoline engine with a displacement of 2.8 l. As it turned out, apart from the absolute sizes, this engine consumption map tends to apply to all gasoline and diesel engines. An engine consumption map P _e = k × b _e ¹ can therefore be created for each type of internal combustion engine, the characteristic constants k and 1 of which may of course differ somewhat from one engine type to another.

As can be seen in FIG. 4, the specific fuel consumption b _{e increases} with increasing mean effective combustion pressure P _e , that is to say with increasing engine output

initially continuously. In the upper pressure range above an average effective combustion pressure denoted by P * _e , the specific fuel consumption b _e no longer changes significantly. The specific fuel consumption associated with this mean effective combustion pressure is marked with b _e *.

To explain the invention, two different operating cases are only arbitrarily indicated in FIG. 4 by way of example. On the one hand, it was assumed that the vehicle would move at a speed of about 50 km / h (with the engine used in the example in 5th gear at a speed n = 1095 min ^-1 ) purely combustion engine. For this propulsion, the internal combustion engine must have an output N _F (50) = 4 kW, whereby it has a comparatively high specific fuel consumption b _e (50). If during this driving phase of the combustion engine 6 is now additionally used to drive the generator-operated electric machine 4 and z. B. a superimposed generator power N _{L is} also controlled by 4 kW, then the internal combustion engine 6 must apply a total power N _F + N _L = 8 kW, whereby it works with a significantly lower specific fuel consumption b ' _e (50). In a corresponding manner, it was assumed that the hybrid vehicle in 5th gear with about 70 km / h (with a speed n = 1570 min ^-1 ) is propelled purely by internal combustion engine, for which purpose the internal combustion engine 6 has a power N _F (70) = 7 , 2 kW must apply. This results in a specific fuel consumption b _e (70). For this example it was assumed that the internal combustion engine is alternatively additionally loaded with a superimposed generator power N _L = 6 kW, ie a total power N _F + N _L = 13.2 kW must be applied. As can be seen, there is also a significant reduction in the specific fuel consumption to b ′ _e (70).

It is easy to understand on the basis of the engine consumption map shown in FIG. 4 that an optimal overall consumption of the hybrid vehicle is achieved when the internal combustion engine 6 in suitable situations in addition to the propulsion power N _F ge straight during hybrid operation be charged with such a superimposed generator power that he works approximately with the mean effective pressure P * _e , if it is exceeded the specific fuel consumption b ' _e would not like to reduce significantly.

Optimal fuel consumption during hybrid driving operation thus arises when the generator-operated electric machine is controlled in such a way that the superimposed generator power N _{L is} just about

is.

Since the stroke volume H and this mean effective combustion pressure P * _e to be determined and determined from the engine consumption map P _e = f (b _e ) represent characteristic constant values known for each engine type, this relationship can also be represented as

N _L = K × n - N _F ,

where K is a characteristic of the respective engine type Kon aunt is.

Due to the well-defined limitation of the superimposed generator power N _L to such a value at which the combustion engine 6 is currently working with approximately the mean effective combustion pressure P * _e , it is achieved that on the one hand the specific fuel consumption for the traction power N _F and the superimposed generator power applied internal combustion engine is kept as low as possible during this time and on the other hand, that the propulsion of the vehicle Ver Ver engine 6 operated as long as possible with the combustion pressure P * _e associated with this low specific fuel consumption b * _e becomes.

Without this limitation of the superimposed generator power N _L, the internal combustion engine would then also be operated with this low specific fuel consumption or a slightly lower one during this operating phase, but only for a possibly much shorter operating time, since a - not limited - higher superimposed one Generator power would of course unnecessarily charge the electrochemical energy store 7 faster than the generator power limited in the aforementioned manner.

As already mentioned at the beginning, a hybrid vehicle can basically be operated in three different operating modes as required. Purely by electric motor, when it comes to emission-free and / or low-noise in special areas of application, purely by internal combustion engine, if, for. B. for longer cross-country trips at higher speeds and ultimately hybrid in the sense of the present invention, that is, according to the respective driving and operating conditions and the specifications of the driver automatically switched to the most favorable operation for the total consumption of the vehicle, which is temporarily can be a purely electric motor drive, a purely internal combustion drive or an internal combustion drive with superimposed generator power. Whether one mode of operation or the other mode of operation is set automatically depends, among other things, on the state of charge of the electrochemical energy store 7 and also on whether the specific fuel consumption b _{e of} the internal combustion engine 6 in the current operating state is greater than that in FIG specific fuel consumption marked with b * _{2 and} belonging to P * _e would be the same or, if applicable, also slightly lower.

A control device required for the operation of a hybrid vehicle according to the invention must therefore have, inter alia, a charge control device monitoring the charge state of the electrochemical energy store 7 and signaling the actual electronic control and regulating device of the vehicle, as well as a device for determining the instantaneous specific fuel consumption b _{e of} the internal combustion engine 6 and to compare this current specific fuel consumption with the aforementioned specific fuel consumption b * _e , which is a known constant characteristic of each engine type. Such a device for determining and comparing the instantaneous specific fuel consumption b _e contains conventional electronic logic and comparison modules as well as electronic storage devices in which, in addition to characteristic vehicle constants, the engine characteristic map according to FIG. 3 and / or the engine consumption map accordingly Fig. 4 of the internal combustion engine 6 are saved.

With the aid of the device for determining and comparing the current specific fuel consumption b _e , the electronic control and regulating device would automatically select the following operating modes during the hybrid operating mode in accordance with the different operating conditions:

A. The capacity of the electrochemical energy store 7 corresponds at least approximately to its nominal capacity K _Ahist ∼0.7 × K _Ahnenn :

With practically fully charged energy storage, the internal combustion engine 6 would generally have no generator power superimposed. Depending on the prevailing operating condition, a purely electromotive propulsion, a purely combustion engine propulsion or a mixed propulsion would be set, ie a simultaneous drive by the internal combustion engine and the electric motor.

If in the present operating situation for a purely internal combustion engine propulsion a specific fuel consumption b _e would result, which is larger, i.e. less favorable than the aforementioned specific fuel consumption b * _e , then in the event that the performance of the comparatively small electric machine 4 for the propulsion is sufficient to be driven purely by an electric motor, but in the event that a higher propulsive power is required, purely combustion engine.

In contrast, when a specific fuel consumption b _e would result in the present operating situation, in purely IC engine propulsion which is equal to or possibly even slightly smaller b than the aforesaid SPE-specific fuel consumption * _e, then a mixed drive would be useful d h. a drive by the combustion engine 6 and additionally by the electric machine 4 ; by the (partial) drive by the electric machine 4 , the electrochemical energy store 7 would namely be partially discharged again, which in turn creates the prerequisite for driving in a corresponding operating situation to optimize consumption with superimposed generator power.

B. The capacity of the electrochemical energy store 7 is considerably lower than its nominal capacity K _Ahist <∼0.7 K _Ahnenn :

With partially discharged electrochemical energy store 7 , depending on the operating situation, either internal combustion engine or internal combustion engine with superimposed generator power is driven, depending on what is more favorable for the overall consumption of the hybrid vehicle in this situation. If the specific fuel consumption b _e in the case of purely internal combustion engine operation is the same or even slightly lower than the aforementioned specific fuel consumption b * _e , then the internal combustion engine 6 is only required to provide traction power, ie N _V = N _F where N _{V is} that of Total engine output to be applied and N _F, as previously stated, the power to be made available by the internal combustion engine for propelling the vehicle.

If, however, a specific fuel consumption b _e would result in purely internal combustion engine operation, which is greater than the aforementioned specific fuel consumption b * _e , then the internal combustion engine 6 would additionally drive the electric machine 4 controlled in the generator operation, in which case the superimposed generator power N _L is controlled or regulated in the manner described above.

An electronic control and regulating device suitable for automatic control of the superimposed generator power N _L in this sense, which is part of an overall regulating device provided for the operation of the hybrid vehicle, is shown in principle in FIG. 2.

This open-loop and closed-loop control device is formed by an electronic logic unit or logic stages containing hybrid control unit 12 , which is, for. B. can be a known microprocessor. In the exemplary embodiment, this hybrid control unit 12 essentially contains, as a core, a computing module 13 , two comparison elements 14 , 15 and an ad element 16 .

The arithmetic module 13 during the driving phase in which the internal combustion engine 6 is acted upon not only with the power N _F required for propulsion of the vehicle but also with a superimposed generator power N _L for driving the electric machine 4 controlled in generator operation one generates a control and regulating signal M _L for the desired optimal modulation of the electric machine 4 and, on the other hand, a control and regulating signal for the corresponding modulation of the internal combustion engine 6 .

The relationship M _L = K * × P * _e - M _F (n) symbolizes that the computing module 13 generates an output or control signal M _L , through which the electric machine 4 and the internal combustion engine 6 are controlled or regulated in this way that for the superimposed generator power N _L as desired, the previously explained relationship

is fulfilled.

Since in practice it is usually not the power but ultimately the torque of the two machines 6 , 4 that is controlled or regulated, it is not this power relationship but the corresponding torque relationship that is entered in the computing module.

The torque relationship entered was written using the mean effective combustion pressure P * _e , because the explanations of the invention made above with reference to FIG. 4 were based in particular on this value. This torque relationship can equally well be formulated using the specific fuel consumption b * _{e associated} with P * _e

M _L = K * × k × b * _e ¹ - M _F (n)

or else

M _L = constant - M _F (n)

since K *, P * _e and k, l and b * _e are characteristic known constants for each motor type.

The control and regulating signal M _L thus generated by the arithmetic module 13 causes the corresponding modulation or regulation of the generator-operated electric machine 4 via an electronic actuator 11, which is only indicated in principle, whereby it is indicated that the setpoint M _L predetermined by the arithmetic module 13 in the comparator 14 is compared with the corresponding actual value of the electric machine 4 supplied there. The resulting system deviation is denoted by M ' _E.

Since the internal combustion engine 6 in this operating phase with superimposed generator power must not only apply the power N _F required for propulsion of the vehicle or must generate the engine torque M _F (n) required to compensate for the driving resistances, the hybrid control unit 12 must also simultaneously to ensure that the internal combustion engine is operated with a correspondingly higher total output N _V = N _F + N _L or a correspondingly higher total torque M _F (n) + M _L , although the vehicle driver applies the accelerator or accelerator pedal 8 has only operated to the extent that the internal combustion engine is operated at a power N _F required to achieve and maintain the desired driving speed or only generates a correspondingly large torque for the propulsion M _F (n).

In an adder 16 of the hybrid control unit 12 , a setpoint value M _F (n) + M _L , which is required for this modulation of the internal combustion engine 6, is generated, which controls or regulates the internal combustion engine 6 as desired via an electronic actuator 10 , which is also only indicated, whereby this target value M _F (n) + M _L is in turn compared in a comparison element 15 with a corresponding actual value M _{V of} the internal combustion engine. The resulting system deviation is denoted by M '(v).

With 9 an electronic logic module or logic stage containing electronic mode switch is indicated, which according to the previously explained criteria on the basis of stored maps and supplied operating parameters automatically the most efficient mode of operation for the respective operating state, namely purely electromotive propulsion, purely internal combustion engine Turn on propulsion or internal combustion engine propulsion with superimposed generator power.

The hybrid control unit 12 is activated only when the internal combustion engine propulsion with superimposed generator power.

As indicated in Fig. 2, on the other hand, from the electronic mode switch 9 with purely electromotive propulsion the actuator 11 of the electric machine 4 and with purely combustion engine toric propulsion the actuator 10 of the internal combustion engine 6 each directly supplied with a control signal to the Elektromaschi ne 4 or Internal combustion engine 6 according to the desire expressed by the driver by operating the accelerator or accelerator pedal 8 .

Reference list

1 input shaft of the automotive gearbox
2 automotive transmissions
3 first switchable disconnect clutch
4 electric machine
5 second switchable disconnect clutch
6 internal combustion engine
7 electrochemical energy storage (drive battery)
8 accelerator pedal
9 electronic mode switch
10 actuator for the internal combustion engine
11 actuator for the electric machine
12 hybrid control unit, e.g. B. microprocessor
13 calculation block
14 comparator
15 comparator
16 adder
N _F Driving or propulsive power of the internal combustion engine
N _L "superimposed" generator power, ie the power of the internal combustion engine applied for the generator drive
b _e specific fuel consumption of the internal combustion engine with pure propulsion
b _e ′ specific fuel consumption of the internal combustion engine with additional drive of the generator-operated electric machine
b _e * a specific value of the specific fuel consumption specified on the basis of the engine consumption map
η _total efficiency for electrical energy generation, storage and conversion into drive energy

Claims (4)

1. A method for operating a hybrid vehicle with an internal combustion engine ( 6 ), in particular a gasoline or diesel engine, and an electric machine ( 4 ), which can be fed as a motor from a rechargeable electrochemical energy store (drive battery 7 ) or as a combustion engine ( 6 ) drivable, the energy storage ( 7 ) aufla dender generator can be operated, the propulsion of the hybrid vehicle either solely by the internal combustion engine ( 6 ), solely by the motor operated as an electric machine ( 4 ), or simultaneously by both and with the internal combustion engine ( 6 ) during the propulsion of the vehicle also drives the electric machine ( 4 ) operated as a generator at the same time, characterized in that
that the internal combustion engine ( 6 ) in driving phases in which its specific fuel consumption is high, when the electrochemical energy store ( 7 ) is at least partially discharged, is additionally loaded with the generator-operated electric machine ( 4 ),
and that the electric machine ( 4 ) is controlled so that the relationship is observed, in which N _{F is} the driving or propulsive power of the internal combustion engine,
N _{L is} the "superimposed" generator power, ie the power of the internal combustion engine additionally applied to drive the electric machine operated as a generator,
η _tot the total efficiency of electrical energy generation, storage and conversion into drive energy,
b _e the specific fuel consumption of the internal combustion engine with pure propulsion, i.e. without additional generator load and
b _e ′ mean the specific fuel consumption of the combustion engine which is additionally loaded with the generator drive. 2. The method according to claim 1, characterized in that the electric machine ( 4 ) is controlled such that the superimposed generator power N _{L is} limited to a value at which the propulsion power N _F and additionally with the drive of the generator-operated electric machine ( 4th ) loaded internal combustion engine ( 6 ) reaches a specific fuel consumption (b _e ′) that is at least in the vicinity of its specific fuel consumption minimum. 3. The method according to claim 2, characterized in that the electric machine ( 4 ) is controlled such that the relationship N _L = K × n - N _{F is} satisfied, wherein N _{L is} the superimposed generator power,
N _{F is} the driving or propulsive power of the internal combustion engine,
n the engine speed and
K is a characteristic constant of the internal combustion engine that is proportional to the stroke volume of the internal combustion engine and that can be determined and determined on the basis of the engine consumption map. 4. Device for performing the method according to claims 1 to 3,
containing among others
a charge control device monitoring the state of charge of the electrochemical energy store ( 7 ),
an electronic storage device for storing the engine map and the engine consumption map as well as characteristic vehicle data,
a device containing electronic logic and arithmetic components for determining the instantaneous specific fuel consumption b _{e of} the non-generator-loaded internal combustion engine ( 6 ) and comparing this value with a one determined on the basis of the stored engine consumption map P _e = f (b _e ) fuel-efficient specific fuel consumption b * _e
an electronic operating mode switch ( 9 ), which, based on the comparison of the current specific fuel consumption b _e with the specified fuel-efficient specific fuel consumption b * _e and the state of charge of the electrochemical energy store ( 7 ) determined by the charging control device, automatically switches over to the current operating state for selects the overall consumption of the most favorable mode of operation of the hybrid vehicle, ie the purely electromotive propulsion, the purely internal combustion engine propulsion or the internal combustion engine propulsion with superimposed generator power N _L ,
an electronic arithmetic modules ( 13 ), comparison elements ( 14 , 15 ) and adding elements ( 16 ) containing hybrid control unit ( 12 ) which, on the one hand, after the hybrid operating mode selected by the electronic mode switching ( 9 ) with internal combustion engine propulsion and superimposed generator power N _L Provided that a torque relationship M _L = K * × P * _e - M _F (n) or a corresponding performance relationship is stored in the computing module ( 13 ) or a setpoint value M _L for the control and which is matched to the current driving state and the desired optimal total consumption Control of the electric machine ( 4 ) and on the other hand, a tuned target value M _L + M _F (n) for the internal combustion engine ( 6 ).