WO2010012613A1

WO2010012613A1 - Braking method for hybrid vehicles

Info

Publication number: WO2010012613A1
Application number: PCT/EP2009/059233
Authority: WO
Inventors: Gerhard Kressel
Original assignee: Robert Bosch Gmbh
Priority date: 2008-07-29
Filing date: 2009-07-17
Publication date: 2010-02-04
Also published as: DE102008040812A1

Abstract

The invention relates to a method for braking a hybrid vehicle (1), wherein the electrical energy (32) obtained in the recuperation operation is fed (28) at least partially and/or at least intermittently (26) to at least one electric heating device (8).

Description

description

title

BREAKDOWN PROCEDURE FOR HYBRID VEHICLES

The invention relates to a method for braking a hybrid vehicle. The invention further relates to a hybrid drive system for a motor vehicle and a hybrid motor vehicle.

Against the background of rising crude oil prices and the emerging change in the global climate due to the release of greenhouse gases, the call for more fuel-efficient and fuel-efficient motor vehicles is becoming increasingly strong.

A promising approach for the realization of such fuel-efficient motor vehicles is in motor vehicles with a hybrid drive system. In the hybrid drive system, in addition to the engine, a motor is used which is driven with a different form of energy, and which at least partially serves to drive the hybrid vehicle. In practice, almost exclusively electric motors are used as additional engines. By using such additional electric drive motors it is possible, on the one hand, to operate the internal combustion engine largely permanently in a particularly energy-efficient speed range and / or torque range. If the internal combustion engine delivers excess energy in a certain driving state which is not required to drive the vehicle, this excess energy can be dissipated with the help of a vehicle Generators are converted into electrical energy that can be cached in an accumulator. The cached energy can be used at a later time to drive the vehicle. As a result, the internal combustion engine can be relieved or completely switched off. Due to the additional acceleration power of the electric motor and the engine can be made smaller, so that also energy can be saved.

In addition, it is also possible to convert the kinetic energy of the vehicle into electrical energy in a deceleration of the vehicle, and to buffer them in the accumulator. As a result, the braking energy can be used for meaningful purposes. This is called recuperation.

Due to the above-mentioned (and further) effects, vehicles with hybrid drive systems are particularly economical and energy-efficient. This applies in particular to operation of the vehicle in city traffic.

Due to the still relatively young technology, however, there are still relatively many, as yet unresolved detail problems that hinder a faster spread of hybrid propulsion systems so far.

Such a problem exists, for example, when driving on long slopes in mountainous terrain. Due to the cost of construction and the weight of batteries, the amount of electrical energy that can be cached in the battery is relatively narrow. If longer downhill sections are now used (for example pass descents in the mountains), then the potential energy of the vehicle can only be stored to some extent in the battery when driving downhill. At some point, the battery is full (ie fully charged), so the Generator is no longer available for decelerating the vehicle in today's hybrid vehicles. The braking effect is then generated in today's hybrid vehicles completely via the brake system (drum brake, disc brake and the like.) And finally converted into heat there.

By this switching to a different brake system results in a different, expended by the driver pedal pressure, which may need to be stronger than the previous pedal pressure. This changed pedal pressure also sets itself at an unforeseeable for the driver time. Such braking system behavior is naturally undesirable.

EP 1 316 696 A2 describes a control unit for speed control or speed control of a radiator fan motor for a heat exchanger of a motor vehicle engine, wherein the control unit is designed to set a setpoint for the fan speed as a function of the engine load. It is in particular proposed to increase the fan speed during a coasting phase of the vehicle (to lower the temperature of the coolant) and then to reduce it again after the end of the coasting phase.

The previously known in the art methods and systems each have system inherent disadvantages that are undesirable.

Therefore, a method is proposed for braking a hybrid vehicle, in which the electrical energy obtained in a recuperation operation of the hybrid vehicle is supplied at least partially and / or at least temporarily to at least one electric heating device. As a result, it is possible to use the generator, or the generator in a generic operated door operating motor, continue to use to decelerate the vehicle. The generated electrical energy can be destroyed in the electric heater. This makes it possible to reduce the aforementioned change in the brake pedal pressure in a simple manner, or to avoid altogether. The brake pedal pressure can thus be kept at least substantially constant. As a result, both the safety and the comfort when driving the vehicle can be increased.

It can prove to be advantageous if the electric heating device heats the fluid of at least one fluid circuit of the hybrid vehicle, in particular the fluid of at least one fluid circuit of an internal combustion engine of the hybrid vehicle, preferably the fluid of a coolant circuit and / or the fluid of a lubricant circuit of a combustion engine. As a rule, such fluid circuits already have heat transfer devices with which heat can be extracted from the corresponding fluid circuits and removed to the environment. Examples of such heat exchangers are coolant coolers and oil coolers in motor vehicles. Since, in particular, the coolant circuit and the lubricant circuit of an internal combustion engine are constructed in such a way that a relatively high heat output can be dissipated, the hitherto customary heat exchangers generally prove to be sufficient to supply the additional heat energy introduced by the electric heater into the corresponding fluid circuit dissipate. In this context, it should be pointed out in particular that the additional thermal energy generated by the at least one electrical heating device is generally released when the internal combustion engine is completely switched off. This applies in particular to full hybrid vehicles. Optionally, the engine may be operated at low power or at idle. On the contrary, it behaves under some operating conditions of the vehicle (for example, in longer passes in winter) so that the temperature of the cooling water drops such that the engine temperature drops below the optimum temperature due to the vehicle heating switched on for comfort purposes. In previous hybrid vehicles, this decrease in engine temperature is often prevented by the fact that the internal combustion engine is turned on, so as to generate waste heat. In such a case, the thermal energy additionally introduced into the fluid circuit by means of the at least one electric heater may not only prove to be non-irritating, but rather highly desirable and fuel-efficient.

An expedient development can result if the electrical energy obtained in the recuperation operation of the hybrid vehicle is only supplied to the at least one heating device when the electrical energy store of the hybrid vehicle is at least substantially fully charged. If necessary, this development can also be realized only temporarily and / or under certain operating conditions. Often, a preferred generation and / or storage of electrical energy proves to be particularly useful because electrical energy in the vehicle represents a particularly "high-quality" and / or expensive form of energy that can be converted easily and with only minor losses in other forms of energy The electrical energy generated can then be used for other purposes, for example for driving the vehicle, for general purposes (eg for lighting purposes, stereos, on-board computer) etc.) or else for the production of heat energy with the help of electric radiators Only when an intermediate storage of electrical energy is no longer possible (because the battery is fully charged) is the generation of other forms of energy avoided. It can be useful if at least one alternative braking system is used for the proportion of a required braking power that exceeds the maximum generator power. For this purpose, for example, the "conventional" brakes (drum brakes, disk brakes, etc.), which are generally required anyway, can be used, again concentrating on obtaining and / or storing the highest possible form of energy, namely extraction and / or storage Only when the dimensions of the generator, the maximum charging power of the vehicle battery or the maximum power of the electric heater is exceeded, will switch to other forms of energy.Thus, a particularly energy-efficient operation of the vehicle can be further promoted be realized temporarily and / or in certain operating conditions of the vehicle.

A further useful development possibility may arise if, during a warm-up phase of the internal combustion engine, the electrical energy obtained in the recuperation operation is at least partially and / or at least temporarily supplied to the at least one electric heater, even if the electrical energy store is not yet fully charged. Due to the faster heating of the internal combustion engine (and thus eg the oil circuit and / or the coolant circuit), it is possible to additionally save energy and / or to improve the exhaust gas behavior of the internal combustion engine. For internal combustion engines have a particularly poor energy efficiency in cold start operation and disproportionately release many pollutants. Thus, the fuel consumption of an internal combustion engine in winter during the first ten minutes of operation may be about twice as high as in the warm operating condition. Also, the wear of an internal combustion engine in the cold state is very high, which damages the internal combustion engine accordingly. In addition, the comfort for the vehicle occupants can be increased, since the heating effect of a coolant heating can start faster.

It is also possible that before and / or during a warm-up phase of the internal combustion engine stored in at least one electrical energy storage electric energy and / or the hybrid vehicle supplied from the outside electrical energy of at least one electric heater is supplied. As a result, the particularly damaging cold-start phase of the internal combustion engine can be shortened in terms of time. A supply of electrical energy from the outside can be done for example in the garage by connecting to the electrical house network. In the case of a suitably dimensioned electrical heating device of, for example, 20 to 25 kilowatts, preheating can be achieved in just two minutes at a correspondingly dimensioned power socket. If the electric "cold start additional heating" is effected by the energy store provided in the vehicle, then it makes sense to allow this only up to a certain defined state of charge of the vehicle battery, in this way a reserve can be kept in stock for certain operating conditions (for example for a vehicle) Stalling and restarting the internal combustion engine - especially in partial hybrid vehicles, for an opportunity to start even after several short haul trips etc.) Normally, however, automobiles are used such that the hybrid vehicle is operated long enough for the hybrid vehicle's energy storage to have enough time to recharge become.

It is also possible to use the hybrid vehicle externally supplied electrical energy, at least in part, to at least partially charge at least one electrical energy storage see. If indeed one Connection possibility for externally supplied electrical energy is provided, the hybrid vehicle can be controlled so that at least an electrical energy storage is emptied towards the end of the ride out at least to a certain extent. The "missing" charge can then be filled up during standstill of the hybrid vehicle by the externally supplied electrical energy and is then available, for example, for a driving operation of the hybrid vehicle, which can be several times cheaper than the energy required by the internal combustion engine manufacture.

Furthermore, a hybrid drive system for a motor vehicle is proposed, which has at least one control device, which is designed and set up so that the hybrid drive system can perform a method with the properties described above. The hybrid drive system then has the already mentioned properties and advantages in an analogous manner. Of course, it is also possible to further develop the hybrid drive system in the sense of the aforementioned training opportunities in an analogous manner.

Also, a hybrid vehicle is proposed, which has such a hybrid drive system. Also, such a hybrid vehicle can be further formed accordingly. The hybrid vehicle can be developed in the sense of the further training options described above. The hybrid vehicle has the already explained above properties and advantages in an analogous manner.

In particular, a hybrid vehicle is proposed, which has at least one electric high-performance radiator, which is preferably arranged in at least one fluid circuit of the hybrid vehicle, in particular in at least one fluid circuit of the internal combustion engine of Hybrid vehicle, preferably in the coolant circuit and / or in the lubricant circuit of the internal combustion engine. In this case, the benefits inherent in the proposed system may be particularly well appreciated.

In the following the invention will be explained in more detail with reference to embodiments and with reference to the accompanying figures. Show it:

1 shows an exemplary embodiment of a hybrid drive system of a hybrid vehicle;

2 shows a first flowchart for the operation of a hybrid vehicle;

3 shows a second flow chart for the operation of a hybrid vehicle.

In Fig. 1, the hybrid drive system 2 of a hybrid vehicle 1 is shown in a schematic view.

The hybrid drive system 2 has a water-cooled combustion engine 3. The water-cooled internal combustion engine 3 has a known, so-called short-circuited coolant circuit 4 and an external coolant circuit 5. The coolant contained in the short-circuited coolant circuit 4 is circulated between the internal combustion engine s and coolant heater 6. The coolant heater 6 may be located, for example, in the housing of an automotive air conditioning system. Of the

Coolant radiator 6 thus represents a heat exchanger which serves to heat the vehicle interior. The coolant flowing through the coolant heater 6, hot coolant can heat the flowing through the coolant heater 6 fresh air for the interior of the motor vehicle 1. The coolant present in the short-circuited coolant circuit 4 can by a mechanically driven coolant circulating pump are circulated, which is usually provided in or on the internal combustion engine 3 (not shown here). In the embodiment shown in FIG. 1, an electrically driven circulating pump 7 is additionally provided in the short-circuited coolant circuit 4. Of course, it is also possible to carry out part or all of the mechanical coolant circulating pumps as electric coolant circulating pumps.

When the temperature of the coolant exceeds a certain level,

also opens the so-called outer coolant circuit 5. In the outer coolant circuit 5, coolant between the engine 3 and a coolant heat exchanger 9 is circulated. Via the coolant heat exchanger 9, waste heat of the internal combustion engine 3 can be released to the environment. The coolant flowing in the outer coolant circuit 5 may be circulated through a coolant circulation pump provided on or in the engine 3. This can also be the same coolant circulation pump, which also circulates the coolant circulating in the short-circuited coolant circuit 4.

In addition, the hybrid drive 2 shown in Fig. 1 in the short-circuited coolant circuit 4, an electrically operated Kühlmittelzuheizer 8 is provided. The electrically operated coolant heater 8 is operated with an increased vehicle electrical system voltage of, for example, 42 volts or 48 volts. Even an increased vehicle electrical system voltage of 200 to 600 volts or even up to 720 volts is possible. In particular, in the latter case, it is possible to use a speed controller at least temporarily for the control of the electrically operated Kühlmittelzuheizers 8. Its power is typically 20 to 25 kilowatts. The electrical heating power of the coolant heater 8, however, can be easily adapted should the specific application require it.

The mechanical drive power generated by the internal combustion engine 3 is supplied via a crankshaft 10 to a planetary gear 13. The torque of the internal combustion engine 3 is divided in the planetary gear 13 on two different output shafts 11, 12. A first output shaft 11 is in mechanical communication with the driven wheels 14 of the hybrid vehicle 1.

In addition, an electrically operated traction motor 15 is arranged on the first output shaft 11. Also, the electrically driven traction motor 15 is mechanically connected to the driven wheels 14 and thereby can drive the hybrid vehicle 1. Depending on the operating state of the hybrid vehicle 1, the hybrid vehicle 1 is driven by the internal combustion engine 3, by the electric traction motor 15 or by both motors 3, 15. 1, a "classic" brake 16, with which the hybrid vehicle 1 can be braked, is provided in the region of the first output shaft 11. The brake 16 is embodied here as a disc brake.

Between the planetary gear 13 and the electrically driven traction motor 15 and between the electrically driven traction motor 15 and the driven wheels 14, an electrically controllable clutch 33, 34 is provided in each case.

In addition to the first output shaft 11 branches off from the planetary gear 13 and a second output shaft 12 from. The second output shaft leads to an electrical generator 17 mechanical energy of the internal combustion engine 3. By means of the electric generator 17 and the speed of the motor vehicle 1 can be controlled. When the from the engine 3 generated mechanical energy is not, or not completely required to drive the hybrid vehicle 1, the excess energy of the internal combustion engine 3 is converted by means of the generator 17 into electrical energy, which can be cached in an accumulator 18. The cached there electrical energy can then be used for example in the electric traction motor 15 for driving the hybrid vehicle 1. When the hybrid vehicle 1 is decelerated, the electric traction motor 15 is operated in a generator mode. Thereby, the kinetic energy of the hybrid vehicle 1 is converted by means of the electric drive motor 15 into electrical energy, which can also be cached in the accumulator 18. There she is available for other tasks (also at a later date). In the event that the hybrid vehicle 1 must be braked very fast, the electric braking performance of the electric traction motor 15 is usually not sufficient. The additional braking power can be applied by the classic brake 16.

The interaction of internal combustion engine 3, electric drive motor 15, generator 17 and accumulator 18 is taken over by an electronic control device 19, which is connected via corresponding lines 20 (control lines, power lines, measurement signal lines, etc.) to the respective components 3, 7, 8, 15, 17, 18 communicates. The electronic control device 19 also takes over the coordination of the operation of electric circulation pump 7 and coolant heater 8. Of course, the electronic control device 19 with other

Sensors, sensors and / or components are related.

The electronic control device 19 may be formed as an independent unit. However, it is also possible for the functions of the electronic control device 19 to be provided by an already provided in the motor vehicle 1. electronic control circuit (for example, a single-board computer).

Possible operating methods for a hybrid vehicle are shown in FIGS. 2 and 3. In this case, the time t is shown along the abscissa 22, while along the ordinate 23 typical characteristics of the corresponding components are shown.

If, under colder ambient conditions (for example in winter), the hybrid vehicle 1 moves at a lower speed over a longer period of time (FIG. 2, beginning with time 24) and thereby decelerates 32, the potential energy of the Hybrid vehicle 1 via the detour of kinetic energy of the hybrid vehicle 1 via the wheels 14 to the electric traction motor 15 supplied, which is operated in a generator mode. The energy generated there is supplied to the accumulator 18 (charge state 27 of the accumulator 18, time interval 25). During downhill driving, the engine 3 is usually off because its power is not needed. After passing through a certain slope distance (time interval 25), the accumulator 18 is fully charged (state of charge 27) and can no longer caching any further electrical energy. As soon as the electronic control device 19 detects this, it switches on the electric circulation pump 7 and the coolant heater 8 in the short-circuited cooling circuit 4 (FIG. 28, time interval 26). The electrical energy coming from the electric

Traction motor 15 is generated, is now destroyed by heating the coolant in the short-circuited coolant circuit 4 28 (delivery of the generated heat energy to the outside air by means of the coolant heater 6 and / or the coolant heat exchanger 9). It is possible to switch on the electric circulation pump and / or a coolant radiator fan only after when (local) a defined (for example, lying in the range of the permissible coolant temperature) coolant temperature has been reached. As a result, the hybrid vehicle 1 can continue to be braked with the aid of the electric traction motor 15. This is an advantage since it represents a wear-free braking process. In addition, not from one

Braking (braking by traction motor 15) to another type of braking (classic brake 16) to be changed, which could lead to a change in braking behavior and to changed pedal forces of the brake pedal. The proposed solution does not change the braking behavior.

Instead of carrying out the braking operation (as far as possible) exclusively by means of the electric brake 15, it is also possible to realize a combination of electrical brake 15 and mechanical brake 16 (at least from the point in time when the accumulator 18 is fully charged).

The converted in the coolant heater 8 electrical energy 28 (time interval 26) can be easily removed via the coolant heater 6 in the short-circuited coolant circuit 4 and / or the coolant heat exchanger 9 of the outer coolant circuit 5. In an internal combustion engine with a power of, for example, 50 kilowatts, the coolant heat exchanger 9 is usually designed so that it can dissipate a heat output of about 250 to 400 kilowatts. In contrast, the electric traction motor 15 is dimensioned in today's hybrid vehicles 1 so that a recuperation in the range of 20 to 25 kilowatts can be generated. From the comparison of the numbers shows that the resulting electrical heat output can be easily dissipated, since the engine 3, as already mentioned, is switched off at this time or is operated at best at low power. If, in cooler ambient conditions, the vehicle interior is heated via the coolant heating element 6, cooling of the coolant occurs when the internal combustion engine is switched off (if no other heating of the coolant takes place). After a certain period of time (for example when driving a longer downhill slope), this temperature reduction can go so far that the temperature of the internal combustion engine 3 threatens to drop below an optimum engine temperature. To avoid an inadmissible lowering of the engine temperature, it must be started so that it generates waste heat.

In the case of the hybrid drive system 2 proposed here, however, the coolant located in the short-circuited cooling circuit 4 is heated 28 (time interval 26) during longer downhill travel via the coolant heater δ. Thereby, an inadmissible lowering of the cooling water temperature can be avoided, so that it is not necessary to start the engine 3. However, at least the period during which the internal combustion engine 3 must be turned on to generate waste heat, can be significantly reduced.

In addition, the electronic control circuit 19 can be set up so that after a cold start of the internal combustion engine 3 (29, FIG. 3), the electrical energy stored in the accumulator 18 is (partially) supplied to the coolant heater 8, to the temperature 31 of the internal combustion engine 3 as much as possible rapidly in an optimal area. For reasons of reliability, the electronic control circuit 19 is connected so that this heating is terminated using accumulator 18, when the accumulator 18 falls below a certain state of charge, for example, 20 percent or 40 percent. In addition, in the hybrid drive system 20 shown in Fig. 1, a socket 21 is provided, via which the hybrid vehicle 1 can be supplied with external electrical energy. This can be done for example in a vehicle garage. The hybrid vehicle can then be started, for example, with a fully charged accumulator 18 and / or with a warm engine 3. Of course, any electrical connection options are possible here, especially those that automatically establish an electrical contact.

Claims

Patent claims

1. A method for braking a hybrid vehicle (1), character- ized in that in a recuperation operation of the hybrid vehicle (1) obtained electrical energy at least partially and / or at least temporarily supplied to at least one electric heater (8).

2. The method according to claim 1, characterized in that the electric heating device (8) heats the fluid of at least one fluid circuit (4, 5) of the hybrid vehicle (1), in particular the fluid of at least one fluid circuit (4, 5) of an internal combustion engine (3). of the hybrid vehicle (1), preferably the fluid of a coolant circuit (4, 5) and / or the fluid of a lubricant circuit of one

Internal combustion engine (3).

3. The method according to claim 1 or 2, characterized in that in the recuperation operation of the hybrid vehicle (1) obtained electrical see only energy of the at least one heater (8) is supplied when the electrical energy store (18) of the hybrid vehicle (1) at least substantially fully charged.

4. The method according to any one of the preceding claims, character- ized in that for the proportion of a required braking power exceeding the maximum generator power (15, 17), at least one alternative braking system (16) is used.

5. Method according to one of the preceding claims, characterized in that during a warm-up phase of the combustion motor (3) the electrical energy obtained in the recuperation operation is at least partially and / or at least temporarily supplied to the at least one electric heater (8), even if the electrical energy store (18) is not yet fully charged.

6. The method according to any one of the preceding claims, characterized in that before and / or during a warm-up phase of the internal combustion engine (3) stored in at least one electrical energy storage (18) stored electrical energy and / or the hybrid vehicle (1) from the outside electrical energy (21) is supplied to the at least one electric heating device (8).

7. A hybrid drive system (2) for a motor vehicle (1), characterized by at least one control device (19), which is designed and arranged such that the hybrid drive system (2) can perform a method according to one of claims 1 to 6.

8. Hybrid vehicle (1), characterized by a hybrid drive system (2) according to claim 7.

9. hybrid vehicle (1), in particular according to claim 8, characterized by at least one electric Hochleistungsheizkörper (8), which preferably in at least one fluid circuit (4, 5) of the hybrid vehicle (1), in particular in at least one fluid circuit (4, 5 ) of the internal combustion engine (3) of the hybrid vehicle (1), preferably in the coolant circuit (4, 5) and / or in the lubricant circuit of the internal combustion engine (3).