DE19729033C1 - Method of operating a drive system, esp. a diesel electric drive system, for motor vehicles - Google Patents

Abstract

The method involves feeding the drive power of a machine operated as a generator in traction mode at least indirectly into a braking device in the form of a hydrodynamic retarder coupled to the machine. The entire power generated by electric drive wheel motors can be fed via the generator into the braking device.

Description

The invention relates to a method for operating a drive system for use in vehicles, especially a diesel-electric one Drive system, in detail with the features from the preamble of Claim 1, further a drive system, in particular a diesel-electric Drive system for use in vehicles to carry out the Procedure, in detail with the features from the preamble of Claim 14. Such a method and drive system are known by the special print G 1401 from J.M. Voith GmbH.

Drive systems in the form of a hybrid drive, d. H. a combination of an internal combustion engine and an electric motor are in one Numerous designs known. The special print by J. M. Voith GmbH, G 1401, discloses a diesel-electric drive system for Commercial vehicles, especially for city buses. This includes at least one at least indirectly coupled with at least one drive wheel and as So-called wheel motor functioning electric motor, which preferably as Transversal flow machine is executed. The individual wheel drive motors are at least one inverter unit with electrical power provided. Furthermore, one is in traction mode, i.e. H. in normal Driving operation in the direction of power flow from the internal combustion engine to the the drive wheel driving electric motor operable as a generator electrical machine provided, which also preferably as Transverse flux machine can be executed. The in traction operation as Electrical machine is mechanically operated with a generator Internal combustion engine, in particular a diesel engine, can be coupled. The Generator is with the electric motors acting as wheel drive motors electrically coupled. To generate the electrical power, the as  Electrical machine operated by a traction generator Four-quadrant inverter controlled. For specifying the setpoints of the Wheel motors (torque, current) and the speed control of the Internal combustion engine is a superordinate driving control provided which u. a. is able to evaluate the driver's request. The as a generator operable electrical machine is at least in Traction operation operated as a generator, which is why this is only in the following is called a generator. The electrical that can be operated as a generator The machine can preferably also be operated in motor operation.

The inverters for the electric motors assigned to the drive wheels and the generator are via a voltage intermediate circuit, preferably in Form of a DC link, coupled together. Here there is also the option of combining the individual inverters into a single one Summarize assembly.

In braking mode, those that act as drive motors Electric motors operated as generators. Controlling the size of the to the generated electric motors generated torque, which leads to the generation of a certain electrical power, which in the DC link can be fed in via the electric motors assigned control devices, which are preferably the the inverter units associated with the electric motors. The Electrical power generated is usually in the intermediate circuit fed, and in a braking resistor, which by means of a Brake actuator can be controlled from the DC link, implemented. In terms of the device, an actuating unit is in the voltage intermediate circuit Form of a brake actuator for controlling the braking resistor provided, the braking resistor as a liquid-cooled resistor is executed and the waste heat generated on it directly or indirectly in the coolant circuit of the internal combustion engine is fed. In  As a rule, only a first part of the power is generated by the generator operated electric motors generated electrical power on Braking resistor implemented. Another second part of the performance of the Electric motors generated in generator mode and in the Voltage intermediate circuit fed electrical power becomes Drive the electrical that can be operated as a generator in traction mode Machine used in engine operation. The generator, which is rigid with the Internal combustion engine is coupled, thus drives the Internal combustion engine, this means that Internal combustion engine is being towed. Part of the second Power share is used to overcome the internal resistance of the Internal combustion engine needed. In addition, the Engine brake device activated. The engine brake device, which also as Exhaust brake is called, used for braking the four-stroke engines required compression work of the compression cycle and the Throttling effect of ejection in the fourth stroke. The The internal combustion engine runs in push mode. To increase the Braking effect, the exhaust pipe can be closed by a throttle valve and / or the fuel supply is switched off. By activating the Engine braking device may have a certain percentage of that of the Electric motors in generator mode generate electrical power in the Diesel engine can be fed and implemented. By the appropriate Design of the diesel-electric drive system and the division of the electrical energy to be converted is possible, for example the braking resistor is only determined for a first power component Size.

A disadvantage of such drive systems is that in addition to the diesel-electric drive system, the braking resistor and the brake actuator must be provided. These components need one certain space and assign a certain, not  neglecting weight. In addition, the cost of this also falls Components. A waiver of the braking resistor for implementation at least a share of those generated by the electric motors in generator operation electrical power is not possible because the engine brake device alone not enough to cover the whole of the electric motors in generator mode generated electrical power and fed into the intermediate circuit to implement.

A version with braking resistor is also in DE-PS 559 147 disclosed. In this a hybrid system is described, comprising an im Traction operation as a generator operated electric machine, which can be electrically coupled to at least one electric drive motor. in the The traction motors are generated as generators in the "braking" operating state operated and the electrical operated in traction as a generator Machine motorized. The braking energy is used for compression in the Cylinders of the internal combustion engine used. In addition, this is Possibility of generating braking energy with braking via one Braking resistor can be combined. The disadvantages apply here as well Version according to the special print G 1401.

Brake systems for conventional drive systems, i. H. a mechanical one Direct drive, are for example from the publications DE 44 46 288 A1 and DE 196 41 557 A1. These are hydrodynamic Brake devices equipped in different forms.

The invention is therefore based on the object of a method for operating to further develop a drive system of the type mentioned at the beginning, that the disadvantages mentioned are avoided. Furthermore, there may be constructive changes to be made to the drive system with little constructive and control engineering effort as well as low costs to realize.  

The achievement of the object is through the features of Claim 1 and the device implementation by the features of Claim 14 characterized. Advantageous designs and Further developments are given in the subclaims.

According to the invention, a drive system for vehicles is included at least one, at least indirectly with a drive wheel connectable electric motor, an internal combustion engine, one with the Internal combustion engine mechanically connectable and in traction mode electric machine that can be operated as a generator and an electric machine Coupling between the generator and the electric motors, such as in Braking operation, d. H. in generator mode with the drive wheels at least indirectly coupled electric motors that operated by the electric motors generate electrical power to drive the generator and thus an operation in engine operation is used and by at least indirect feed into one that can be coupled to the generator  Braking device converted into a hydrodynamic retarder becomes. Drive the vehicle and the generator-operated electric motors thus the generator with an existing and activated electrical clutch and the active elements of the braking devices. At this The braking device then becomes a braking reaction torque at least indirectly which generates that which can be operated as a generator in traction mode opposite electrical machine generated in motor operation torque is directed. The electrical that can be operated as a generator in traction mode The machine continuously withdraws from the DC link during motor operation electrical power, so that according to the control of the Electric motors in generator operation over a longer period of time certain braking torque on the drive wheels, which by the Characterized generated torque in generator operation of the electric motors is generated.

The solution according to the invention makes it possible to overcome the disadvantages of an embodiment to avoid according to the state of the art, in particular the electrical braking resistor and the necessary control engineering effort can be dispensed with. Through the feed at least a significant part of the electric motors in the Generator operation generated electrical power in a braking device offers the advantage of already known conventional braking devices to fall back on, which are already produced in large numbers. Of others are on the power electronics side, especially in the area of DC link, no additional components required, see above that the diesel-electric drive is significantly simplified. The stake conventional braking devices also has the advantage that it already tried and tested and therefore essentially error-free working technologies.

The entire electrical power generated in the BRAKE operating state by the electric motors that can be operated as a generator is fed into at least one braking device via the generator, which in this case is operated in engine operation. The braking devices can be designed in different ways. It is possible to use additional braking devices separately from the internal combustion engine, for example in the form

• 1. a hydrodynamic retarder according to the invention,
• 2. an electric eddy current brake.

The braking device can be operated separately or additionally by using certain measures on the internal combustion engine, e.g. B. in the form a constant choke.

A distinction can be made between two modes of operation:

• 1. In each case a first share of those used as wheel drive motors functioning electric motors in the operating state BRAKES in total electrical output generated during generator operation to drive the internal combustion engine via the in Traction operation as a generator operated machine, which in this Operating state is operated by motor, used, the Internal combustion engine already form a first braking device can, and a second share of those as wheel drive motors acting electric motors generated in generator mode total electrical power is transferred to a second braking device hydrodynamic retarder, fed.
• 2. The electric motors acting as wheel drive motors in the total electrical power generated during generator operation either in a first braking device or in a second Braking device according to the invention in the form of a hydrodynamic Retarders fed.

According to the desired mode of operation in braking mode are then To design drive systems. In the former case, the drive system especially the generator or the generator in traction mode operable electrical machine assigned to the second braking device. The mechanical connection between the internal combustion engine and The generator remains in operation during the BRAKES operating state.

For the second mode of operation, the drive system in the event that it the engine brake device has been developed accordingly Execution, such as the constant throttle, is free of second braking device. Another possibility is that Execute drive system such that the second braking device is provided, but between the generator and Internal combustion engine such an interruption of the power flow it is possible for the internal combustion engine to be decoupled from the generator becomes.

For explanatory purposes, also in the event that a generation of a Braking torque only via the separate to the internal combustion engine provided braking device takes place in the following Designs referred to as the second braking device.

There are a multitude of possibilities for arranging the second brake device in the drive system. In particular, the braking devices are braking systems in which the braking torques are generated by torques. The second braking device, which is designed as a hydrodynamic retarder, can either

• a) based on the direction of force flow  in traction mode in front of the internal combustion engine, d. H. for example on the fan side in the area of the crankshaft journal or but
• b) based on the direction of power flow in traction mode behind the Internal combustion engine and before that can be operated as a generator electrical machine.

The coupling of the second brake device to the crankshaft or Output shaft of the internal combustion engine and / or the connecting shaft between the internal combustion engine and the generator can either directly or via a high drive.

The arrangement of the second braking device directly on the crankshaft or the output shaft of the internal combustion engine, d. H. the Main powertrain, requires a mechanical or functional Decoupling in the DRIVE operating state, d. H. in non-braking mode, between the second braking device and the main drive train or crankshaft is possible because otherwise in traction mode, i.e. H. the drive of the wheels on the internal combustion engine significant proportions of the Internal combustion engine generated power as power loss in the Brake devices are fed. This can be done in detail achieved that the rotors - when executing the second Brake device as a hydrodynamic retarder, the rotor blade wheel and when the second braking device is designed as an electrical one Eddy current brake of the rotor - for example via a corresponding one Coupling device - either with the crankshaft or the Main drive train rotatably connectable or decoupled from them are. The functional decoupling of a braking device in the form of a hydrodynamic retarder takes place by emptying in the non-braking mode. In the unfilled state, however, power components are also used  Circulation of the air masses between the rotor and stator impeller is required which is then withdrawn from the main drive train as a power loss.

If the second braking device is arranged in relation to the crankshaft or the output shaft of the internal combustion engine and / or the connecting shaft between the internal combustion engine and an electrical machine which can be operated as a generator and which can preferably be coupled to the above-mentioned shafts via a high drive, there is activation and deactivation of the second braking device the following options:

• - Coupling and uncoupling of the branch from the main drive train, the Crankshaft or the output shaft and / or
• - The coupling or uncoupling of the rotor of the braking device from Second branch.

To implement the coupling functions are preferred conventional coupling devices, for example in the form of synchronizable dog clutches used. For the execution of the High drive preferably find simple speed Torque conversion devices comprising at least one Spur gear train, use. Here, too, is only functional Decoupling of the second braking device is conceivable, for example at Execution of the second braking device in the form of a hydrodynamic Retarders by emptying the working circuit. However, then the powertrain in the fraction operation power shares to drive the Secondary branch withdrawn, which is why this possibility is limited to Application will come.

Designs of the drive system in which the second braking device, based on the direction of power flow in traction, before  Internal combustion engine, d. H. arranged on the side of the fan drive are only operable after the first mode of operation. This means that in in any case for the purpose of feeding at least the second Power share in the second braking device Internal combustion engine via the electrical operated as a generator Machine must be driven. It is optional whether the first Power share of the electric motors that act as drive motors total electrical power generated in generator operation only for Overcoming the internal frictional resistances of the Internal combustion engine is used and thus by the Internal combustion engine a low braking effect can be achieved or whether the internal combustion engine is the first effective Brake device is used. In the latter case, this includes to take appropriate measures on the internal combustion engine, which enables an increase in the engine braking effect, for example that Close the exhaust pipe with a throttle valve and shut it down the fuel supply. Furthermore, the internal combustion engine can Increasing the engine braking effect with a constant throttle become.

The latter options, which the use of Include internal combustion engine as the first braking device, offer the Advantage that the second braking device corresponds to that of the first Braking device implemented and used first power share lower in terms of the absorption capacity of the second power component must be dimensioned. Furthermore, this first mode of operation offers which is due to the combined use of internal combustion engines and additional separate braking devices as braking devices distinguished, offers the advantage due to the dimensioning options a small space requirement and low cost. in the Only the second braking device is to be provided during the drive system  the possibilities that a conventionally designed drive system already has offers, can be optimally used.

The first mode of operation can also be arranged with the second Braking device or the retarder, based on the direction of force flow in Traction operation, behind the internal combustion engine and in front of the Generator can be realized. In this case, even during the Operating state BRAKES a coupling between the im Traction operation as a generator operated electric machine and the Ensure internal combustion engine. Both, Internal combustion engine and braking device, are in parallel with the corresponding power shares of the total electrical power generated provided. It is also conceivable in this embodiment of the drive system that in the first mode of operation of the internal combustion engine implemented or used first performance share only that Maintaining at least idle operation of the Internal combustion engine is used. In this case, an essential part the total electrical power generated at the second braking device implemented. A distribution of the performance shares in the same way Internal combustion engine and second braking device is also possible.

The determination of those to be implemented on the individual braking devices Performance shares are made for each specific application by selection and design of the braking devices. The realization of the Performance allocation and the necessary to be realized Measures, in particular the design of the braking devices, are in the Expert's discretion. This is stopped, the whole Drive system, especially the individual components dimension that at least corresponding minimum power components of Both braking devices can be implemented.  

To implement the second possible mode of operation, i. H. only the Implementation of the total electrical power generated at one of the possible braking devices - first braking device or second Brake device -, the drive systems can also be different be modified. In the event of implementation of the electrical generated Total output on the first braking device, which of the Internal combustion engine or a component coupled to it is formed, the drive system can be free from another second Brake device to be executed. This has the advantage that the Method according to the invention without additional measures, in particular Conversion measures in conventional hybrid drive trains at which the engine brake devices already have in the corresponding Modifications exist, can be carried out.

Such a modification consists in the provision of a compression valve Motor brake, as in Motortechnische Zeitschrift 56 (1995) 7/8. Pp. 418-423. This constant throttle motor brake is a small one additional valve in the cylinder head during engine braking (with and without an engine brake flap, d. H. Exhaust flap) permanently open. This, Valves assigned to the individual cylinder heads are used together with Compressed air operated. The valve causes that already when compressing the Air in the combustion chamber contains a small part of this compressed air the exhaust is blown off, but because of the smaller calibrated Überströmquerschnittes a relatively high compression pressure in the Combustion chamber is generated. In operation in the area of the top dead center of the Pistons in the compression cycle then escape a large part of the air. In order to the pressure in the combustion chamber drops sharply, and the piston is only included with a lower force. The works in the exhaust stroke Piston against that generated by the closed brake flap Exhaust back pressure. The decompression valve is no longer just there kept open throughout the work cycle, but only  for a short time from top dead center to a certain one Angular area after top dead center opened in the compression cycle. This will do the full compression work during the compression phase won and the maximum possible cylinder pressure reached. If then the decompression valve is opened, most of the compressed Flow air into the exhaust manifold. Due to the reduced cylinder pressure the piston is no longer pressed down. After by the limited overflow cross-section not the entire cylinder filling can flow out, remains sufficient even after the expansion cycle Air mass in the combustion chamber in order to push against a closed one Brake flap to be able to win push-out work. In detail this is System described in detail in the above publication. Herewith this document will be used to describe the Decompression valve engine brake fully in the Disclosure content of this application included.

The second possibility of realizing the second mode of operation is in that the internal combustion engine completely from the generator to decouple the operating state of the BRAKES and those of the as Electric motors that function as wheel drive motors produce electrical ones Completely reduce overall performance in a second braking device or to implement. For this purpose you can choose between the Internal combustion engine and the electrical operated as a generator Machine a device for interrupting the flow of power, preferably in the form of a switchable clutch. The second Braking device is either directly on a connecting shaft between the Internal combustion engine and the electrical operated as a generator Machine arranged or in a branch to this connecting shaft via a high drive. When the retarder is arranged directly on it Connection shaft is preferably a switch on and off via a To provide coupling device. When arranged in a branch to  Connecting shaft, d. H. when driving via a high drive, either the High drive and / or the braking device with the connecting shaft or at least indirectly coupled to the connecting shaft via the high drive his. In this case too, the individual switchable elements Coupling devices, preferably in the form of synchronized Claw clutches can be activated.

Preferably only a second braking device is used. Conceivable is, however, the use of several, side by side or optionally with the Generator of connectable braking devices.

According to the invention, the second braking device is designed in the form of a hydrodynamic retarder. The hydrodynamic retarder has at least one rotor blade wheel which can be connected at least indirectly non-rotatably to the generator drive shaft and a stator blade wheel which is stationary with respect to the rotating parts. The stator blade wheel itself can be formed by a fixed housing. The rotor blade wheel and the stator blade wheel form a toroidal working space with one another, which can be filled with an operating medium. Either a hydraulic fluid, such as oil or water, can be used as the operating means of the hydrodynamic retarder. Designs of a hydrodynamic retarder in the form of a water pump retarder are known from a large number of publications. The following could be mentioned in detail:

• 1. DE 44 08 349 A1
• 2. DE 195 01 853 A1
• 3. DE 44 40 163 A1
• 4. DE 44 08 350 A1.

The disclosure content of these documents for arrangement and Operating mode of the retarder is hereby fully included in the Disclosure content of this application included.

When using water as the operating medium, there is a possibility that Operating resources from the coolant circuit of the internal combustion engine use. In this case the hydrodynamic retarder is either in a secondary branch or in series with the coolant circuit Internal combustion engine switched. When arranged in a row, the hydrodynamic retarders, especially the work area of the hydrodynamic retarder, constantly flowed through by the coolant. By corresponding adjustability of the inlet cross sections and the Flow cross-sections to and from the retarder can affect how the hydrodynamic retarder can be determined. With a large inlet cross-section and low drain cross-section is achieved using the hydrodynamic retarder generates a high braking torque in the BRAKE state. With little Inlet cross-section and large outlet cross-section works the rotor blade wheel of the hydrodynamic retarder as a pump wheel and is used for circulation the coolant liquid in the coolant circuit of the internal combustion engine. In this case, an additional pump device in the form of a Water pump can be saved. The rotor blade wheel of the hydrodynamic retarder is either directly with the crankshaft, the output shaft of the internal combustion engine and / or the Connection shaft between the internal combustion engine and the Generator operated machine, coupled. Furthermore there is also the Possibility to use the hydrodynamic retarder in the secondary branch Arrange the main drive train and the rotor blade wheel via a To drive high drive. In both cases there is the possibility of Realization of the functioning of the hydrodynamic retarder as Water pump and as a braking device.  

When arranging the hydrodynamic retarder in a switchable A branch is added to the coolant circuit of the internal combustion engine corresponding braking torque only when the Resource circuit of the hydrodynamic retarder to Coolant circuit of the internal combustion engine realized.

When operating the hydrodynamic retarder with the operating fluid oil or water, however, it is important to ensure that it is functional Connectivity of the hydrodynamic retarder with the filling or Emptying the work area goes hand in hand.

The hydrodynamic retarder itself can also be in the range of Crankshaft journal, d. H. based on the traction before Internal combustion engine can be arranged in the direction of power flow. Conceivable is however also an arrangement in the direction of power flow behind the Internal combustion engine and in front of the generator.

The resource of the hydrodynamic retarder can also from a hydraulic fluid, preferably oil. The hydrodynamic retarder, in particular its, is then preferred Cooling circuit, via a heat exchanger with the coolant circuit Internal combustion engine coupled.

The solution according to the invention enables existing ones optimal use of diesel-electric drive systems. If one is provided Another second braking device is designed for the individual Limit units according to the requirements of the individual case. The Arrangement options for the second braking device also take place according to the requirements of the individual case. The constructive execution is in the field of activity of a specialist in this field. The solution according to the invention enables rapid implementation of the  generator operation of the wheel drive motors Electric motors generated total electrical power and thus the Generation of a high braking effect due to the rapid implementation of the driving performance initiated on or via the drive wheels. It is too take into account that not all of it is fed into the DC link electrical power through the functioning of the braking devices degraded but also a part to overcome the frictional resistance on the Internal combustion engine and the individual braking devices required becomes.

The solution according to the invention is described below with reference to figures explained.

The following is shown in detail in the figures:

Figs. 1a and 1b show a propulsion system according to the invention to feed the electric power generated by the drive motors acting as the electric motors in the operating state BRAKES in generator mode into a first and a second braking means;

Fig. 2 shows a drive system in which the total electrical power generated is essentially fed into a first braking device in the form of the internal combustion engine;

Fig. 3 illustrates an embodiment of a drive system according to the invention for feeding the total electric power generated by the drive motors acting as the electric motors in the regenerative mode to a second braking device in the form of a hydrodynamic retarder.

The Fig. 1a shows a drive system 1, comprising at least one, at least one drive wheel 2 at least indirectly driving electric motor 3. Furthermore, an internal combustion engine 4 is provided, which is mechanically coupled to an electrical machine 5 that can be operated as a generator in traction mode. The electric motors 3 functioning as drive motors and the electric machine 5 which can be operated as a generator are preferably designed as a transverse flux machine. The electric motors 3 functioning as wheel drive motors are supplied with electrical power via an inverter unit 6 . A further inverter unit 7 is assigned to the generator 5 to control the electrical power that can be generated. The generator 5 and the electric motors 3 are electrically coupled to one another. For this purpose, the inverter units 7 and 6 assigned to the electrical machine 5 , which can be operated as a generator, and the electric motor 3 are coupled to one another via a voltage intermediate circuit, preferably a DC voltage intermediate circuit 8 .

Takes place in the operating state BRAKES, in which usually no power flow from the engine to the driving wheel 2, a driving torque M _DRIVE is introduced at the drive wheels. 2 This effects the generator operation of the electric motors 3 that function as all wheel drive motors. In particular, the rotor of the electric motor 3 functioning as a wheel drive motor is driven via the mechanical coupling with the drive wheel. In this way, according to the control of the inverter unit, a torque is generated which is opposite to the driving torque and can be referred to as the braking torque. As a result, a certain electrical power P is generated _electrically by the electric motor 3 operated as a generator. This power is fed into the voltage intermediate circuit 8 and fed to the electrical machine 5 which can be operated as a generator in traction mode. This electrical machine 5 is now operated by a motor and drives the internal combustion engine via the coupling to the internal combustion engine 4 , here the connecting shaft 9 . The entire electrical power P generated by the generator-operated electric motors 3 is preferably fed _electrically via the generator 5 into the internal combustion engine 4 and a further second braking device in the form of a hydrodynamic retarder 10 . The internal combustion engine 4 and the hydrodynamic retarder 10 are arranged in series. The total power supplied to the generator 5 is divided into two power components - a first power component and a second power component. The first power component is used for the internal combustion engine 4 , in particular for towing operation. The second power component is fed into the hydrodynamic retarder 10 . In the case shown, the hydrodynamic retarder 10 is arranged in series with the internal combustion engine 4 . With regard to the power flow present in the traction mode, the hydrodynamic retarder 10 is arranged in front of the internal combustion engine 4 . The hydrodynamic retarder 10 comprises a rotor blade wheel 11 and a stator blade wheel 12 , which together form a toroidal working space 13 for circulating the operating medium. The rotor blade wheel 11 is coupled to the crankshaft 15 of the internal combustion engine 4 via a countershaft 14 . The reduction gear 14 is designed in the form of a spur gear train. The spur gear 16 of the countershaft 14 , which is coupled to the crankshaft 15 , is arranged on the fan side on the fan side and preferably “on the fly” on the crankshaft journal.

The coolant liquid of the cooling circuit 17 assigned to the internal combustion engine 4 functions as the operating medium for the hydrodynamic retarder 10 . In the case shown, the working circuit of the hydrodynamic retarder 10 is connected in series with the coolant circuit 17 of the internal combustion engine 4 . In the coolant circuit 17 , a cooling device 18 is arranged, to which a fan wheel, which is also driven by the crankshaft, is assigned. The hydrodynamic retarder 10 is located in the flow direction behind the cooling device 18 and in front of the internal combustion engine 4 . A line 9 connects the cooler outlet 20 to the liquid inlet 21 on the hydrodynamic retarder 10 . A line 22 connects the liquid outlet 23 on the retarder 10 to the cooler inlet 24 via the internal combustion engine 4 . The hydrodynamic retarder 10 is associated with a further valve device 25, which enables different modes of operation of the hydrodynamic retarder 10th In normal traction operation, ie driving the vehicle via the internal combustion engine 4 , the coolant liquid in the coolant circuit 17 is circulated with the help of the rotor blade wheel 11 of the hydrodynamic retarder 10 . To ensure that there is no high braking torque, the flow cross section at the outlet 23 of the hydrodynamic retarder is larger than at the fluid inlet 21 . This is realized by the valve device 25 . The valve device 25 , which is connected downstream of the hydrodynamic retarder 10 in the flow direction, is designed in the case shown as a continuously adjustable throttle valve. In a first limit position, which corresponds to non-braking operation, the throttle valve releases a maximum flow cross section in line 22 . This flow cross section either corresponds to the flow cross section in the feed line to the hydrodynamic retarder 10 , ie the connecting line 9 , or is larger. In the second operating state, BRAKING, ie when the second power component of the total electrical power P _electrical is fed into the hydrodynamic retarder 10 , the valve device 25 is brought into a position which reduces the flow cross section in the line 22 compared to that of the line 9 , in order to act on the hydrodynamic retarder 10 generate a back pressure that is required to generate the braking torque.

In traction mode, in which the hydrodynamic retarder 10 , which is embodied here as a so-called water pump retarder, functions as a coolant circulation pump in the coolant circuit 17 , the rotor blade wheel 11 is driven to circulate the coolant liquid in the coolant circuit 17 via the countershaft 14 from the crankshaft 15 of the internal combustion engine 4 . In braking operation, the drive takes place via the electric machine 5 , which can be operated as a generator, the internal combustion engine 4 , in particular the crankshaft 15 and the countershaft 14 .

The valve device 25 for realizing the two functions can also be designed differently. For example, in order to implement the switching process from non-operating to braking operation and vice versa, this can comprise two valves, one valve being arranged as a switching valve in the bypass to the valve downstream of the hydrodynamic retarder 10 at the outlet 23 . The changeover valve then has at least two switch positions, which make it possible for a maximum flow cross section in the connecting line from the retarder outlet 23 to the cooler inlet 24 to be released between the liquid outlet 23 from the retarder and the internal combustion engine in a first switch position, while in a second switching division the Switching valve a throttle-like constriction between the hydrodynamic retarder 10 and the internal combustion engine 4 is effective, which causes a strong back pressure on the retarder. For this purpose, the changeover valve can be designed, for example, as a two-way valve. The valve downstream of the retarder 10 at the retarder outlet 23 is then preferably not designed to be adjustable. The first switching position of the changeover valve corresponds to the non-braking operation, ie the rotor blade wheel conveys the coolant liquid in the cooling circuit 17 . The second switching position corresponds to the braking mode, ie the hydrodynamic retarder 10 generates a high braking torque. In the drive system shown in FIG. 1a, the level of the braking torque can be variably set with the valve device 25 , ie the continuously variable throttle valve. In the case of designs of valve devices which only implement the two switching positions, ie braking operation and non-braking operation, the braking torque can be adjusted by means of additional measures, for example the pivoting of the stator vane wheel.

The total power provided by the generator 5 for the braking devices essentially corresponds to the total electrical power P _electrical generated by means of the electric motors. Neither performance is exactly the same, since certain power losses must be taken into account when transferring the total electrical power generated to the individual braking devices. In the explanations of the mode of operation in the BRAKE operating state, the total power supplied to the braking devices via the generator 5 is therefore understood to mean the power which remains after deducting the power losses from the total electrical power.

The first power component of the total electrical power, which is supplied via the generator to the internal combustion engine, can either be dimensioned such that only the internal combustion engine works in towing mode, ie the individual piston units are moved via the crankshaft. In this case, the first power component corresponds to the power required to overcome the friction in the internal combustion engine 4 . The first power component can be increased by providing additional measures for realizing the engine brake function on the internal combustion engine. In this case, either a throttle valve can be provided in the exhaust pipe or a so-called decompression valve. When using a constant throttle, a small additional valve in the bypass to the exhaust valve is integrated in the cylinder head, which is continuously open during braking. As a result, even when the air in the combustion chamber is compressed, a small part of the compressed air is discharged into the exhaust, but because of the smaller, calibrated overflow cross section, a relatively high compression pressure is nevertheless achieved. A large part of the air then escapes in the area of the top dead center of the piston in the compression stroke. As a result, the pressure in the combustion chamber drops sharply and the piston is only pressed down with less force. In the exhaust stroke, the piston then works against the exhaust gas back pressure generated by the closed brake flap. When using the decompression valve, it is no longer kept open during the entire working cycle, but only for a short time, which is described when moving from top dead center to a certain angle after top dead center. This means that full compression work is gained during the compression phase and the maximum possible cylinder pressure is reached. When the compression valve is opened, most of the compressed air can flow into the exhaust manifold. Due to the reduced cylinder pressure, the piston is no longer pressed down. Since the entire cylinder charge cannot flow out due to the limited overcurrent cross section, sufficient air mass remains in the combustion chamber even after the expansion stroke to perform push-out work against the closed brake flap in the extension stroke. The decompression valve is preferably clocked.

In the drive system shown in Fig. 1a, in which the second braking device is arranged in the power flow direction, based on the traction operation, in front of the internal combustion engine, it is necessary to brake the internal combustion engine in the operating state for the purpose of feeding power into the hydrodynamic retarder to drive. In contrast, Fig. 1b shows in which the hydrodynamic retarder 10 in the power flow with respect to the traction operation, after the internal combustion engine 4 and the generator 5 is arranged in front of an embodiment. In this case, if an additional separating device is provided, as described in FIG. 3, the internal combustion engine 4 can be mechanically decoupled from the generator 5 . In that case, only the second braking device is then used; ie the hydrodynamic retarder 10 is used to convert the total electrical power P _electrical generated which is fed to the generator and thus to the braking device 10 coupled to the generator 5 . Shown in the other case, as shown in Fig. 1b, which is free from a means for interrupting the power flow between the internal combustion engine 4 and the generator 5, the total electrical power generated by the electric motors P is _electrically split into two power fractions which both the internal combustion engine 4 and the second braking device, the hydrodynamic retarder 10 , are implemented or used up. Both the internal combustion engine and the second braking device 10 can be arranged in series or, as shown here, parallel to one another.

In FIG. 1b, the hydrodynamic retarder 10 is in a secondary branch to the main drive train, which is described by the connection between the internal combustion engine 4 and the generator 5 is arranged. The secondary branch can, as shown in FIG. 1b, be coupled or uncoupled from the main drive train, in particular the connecting shaft 9 between the internal combustion engine 4 and the generator 5 , via a corresponding coupling device. This coupling can, for example, via a synchronizable claw clutch, which drives the rotationally fixed connection of a spur gear 30 of the high drive 31 , which the secondary branch, here designated 32 , via the main drive train, ie the connecting shaft 9 , and with the connecting shaft 9 in the mode of operation Drive of the secondary branch 32 connects the spur gear 30 to the connecting shaft 9 in a rotationally fixed manner. Such synchronization devices are known, for example, from "How does it work?"Meyer's Lexikonverlag, 3rd edition, page 324. The disclosure in this regard is hereby included in the disclosure content of this application.

In the solution shown in FIG. 1b, a first power component of the total power output by the generator 5 in motor operation in the direction of the internal combustion engine is fed to the secondary branch 32 and thus to the second braking device 10 via the high drive 31 , while a first power component is fed into the internal combustion engine becomes. In this case too, the first power component that is supplied to the internal combustion engine 4 can only correspond to the power required to overcome the internal resistances in the internal combustion engine. In addition, however, the internal combustion engine 4 can also take over the engine braking function in that the internal combustion engine 4 is assigned corresponding devices, for example a throttle valve in the exhaust pipe and a decompression valve. The retarder 10 can be designed in accordance with the size of the first power component. For example, water in the form of the coolant liquid or oil can be used as the operating medium. In the former case, the hydrodynamic retarder 10 can be arranged either in series or parallel to a coolant circuit, not shown here, of the internal combustion engine. When arranged in series, however, it is necessary that the rotor blade wheel of the hydrodynamic retarder 10 also be coupled during the traction operation, ie thus continuously via the high drive 31 with the main drive train, in particular the connecting shaft 9 between the internal combustion engine 4 and the electrical machine 5 which can be operated as a generator is.

In the embodiments described in FIGS. 1a and 1b, the total electrical power generated by the electric motors 3 is introduced via the electrical machine 5, which can be operated as a generator, to two devices for generating a braking effect. These two devices, ie the first and the second braking device, can be arranged in series or in parallel with one another.

In the embodiment of an arrangement of the second braking device in the form of a hydrodynamic retarder 10 in the secondary branch shown in FIG. 1b, the hydrodynamic retarder can either simply be filled and emptied from the main drive train, in particular the connecting shaft 9 between the internal combustion engine 4 and the electrical that can be operated as a generator Machine 5 , be switched on. In this case, however, the rotor blade wheel rotates continuously in the non-braking mode, which, due to the air masses circulated between the motor and the stator blade wheel, leads to a corresponding loss torque in traction mode. A number of measures are possible to avoid the loss of torque; these consist, for example, of swiveling the stator impeller out of its position coaxial with the rotor impeller in non-braking operation and thereby achieving less overlap between the rotor and stator impeller of the hydrodynamic retarder 10 than in braking operation. In this case, no stable meridian flow can develop between the individual blades of the rotor blade wheel and the stator blade wheel. A further possibility is to couple or decouple the rotor blade wheel from the secondary branch 32 or to provide options for coupling or uncoupling the entire high drive 31 from the main drive train, in particular the connecting shaft 9 .

The hydrodynamic retarder 10 can only be used as a water pump retarder only in those cases in which the rotor blade wheel is also driven via the main drive train in traction mode and the hydrodynamic retarder, in particular its operating medium circuit, is arranged in the coolant circuit of the internal combustion engine 4 .

Fig. 2 illustrates an embodiment of a drive system, wherein the measures of the internal combustion engine is available to be used for generating a braking effect. The drive system is also constructed like that described in FIGS. 1a and 1b, which is why the same reference numerals are used for the same elements. The difference is that the drive system is free from a second braking device. In this case, the generator 5 and the operated in traction operation as a generator, the electrical machine 5 supplied electrical total power P is _{electrically,} which is one of which acts as wheel drive motors electric motors 3 generated in the generator mode, implemented only through the internal combustion engine 4 and consumed. In this case, the internal combustion engine 4 functions as the first braking device, to which the entire drive power is supplied by the generator 5 . Appropriate measures, for example the provision of a constant throttle or a decompression valve, are required on the internal combustion engine 4 for the effective implementation of the drive power. With regard to the design of this decompression valve and its control, reference is made to the publication Motortechnische Zeitschrift 56 (1995) 7/8, page 418-423. The content of this document with regard to the structure, arrangement and mode of operation of the decompression valve is hereby fully incorporated into the disclosure content of this application.

FIG. 3 shows a further embodiment of a drive system in which a decoupling, ie an interruption of the flow of force between the internal combustion engine 4 and the generator 5 , is possible. The interruption of the power flow between the internal combustion engine 4 and the electrical machine 5 , which can be operated as a generator, takes place, for example, via a switchable clutch 35 . This switchable clutch is arranged downstream of the power flow direction of the internal combustion engine 4 in relation to the traction operation and is arranged in front of the secondary branch 32 which can be coupled to the generator shaft 36 via a high drive 31 and in which the second braking device in the form of the hydrodynamic retarder 10 is arranged. In non-braking operation, the drive wheel is driven by the internal combustion engine 4 via the closed clutch 35 , the electrical machine 5 operated as a generator in this state, the voltage intermediate circuit 8 and the electric motors 3 . In the operating state BRAKES, a torque is generated on the rotors of the electric motors 3 driven by the drive wheel 2 , which enables the generation and feeding of an electrical power P _electrically into the voltage intermediate circuit 8 and is used to drive the generator 5 in motor operation. The coupling device 35 is released, ie the power flow between the electrical machine 5 , which can be operated as a generator, and the internal combustion engine is interrupted. The entire power generated on the generator 5 on the basis of this electrical power supplied via the intermediate circuit 8 is fed to the secondary branch 32 via the high drive 31 . Here, too, the hydrodynamic retarder 10 can either be switched on or off via the filling or emptying, the rotor impeller running empty in the emptied state and causing a reaction moment on the stator impeller due to the circulation of the air masses. On the other hand, there is the possibility of mechanically decoupling the rotor blade wheel from the secondary branch 32 , or else the entire high drive 31 can be decoupled from the drive train via a coupling device, not shown in detail here, for example in the form of a synchronized claw clutch.

Claims (25)

1. A method for operating a drive system for vehicles, in particular a diesel-electric drive system, comprising

• - At least one electric motor that can be at least indirectly coupled to a drive wheel;
• - an internal combustion engine;
• - An electrical machine that can be mechanically coupled to the internal combustion engine and operated as a generator in traction mode; an electrical coupling is provided between the electric motors and the generator;
• 1.1 in which the electrical power generated in the regenerative operation of the electric motors acting as wheel drive motors is used to brake the vehicle;
• 1.2 at which the electrical power generated in generator operation of the electric motors is used to operate the electric machine that can be operated as a generator in traction mode; characterized by the following characteristic:
• 1.3 The drive power of the machine which can be operated as a generator in traction mode is fed at least indirectly into a braking device which can be coupled to it in the form of a hydrodynamic retarder.

2. The method according to claim 1, characterized in that the entire, of those acting as wheel drive motors Electric motors generated in generator mode Power through the generator into the braking device in the form of the hydrodynamic retarder is fed.   3. The method according to any one of claims 1 or 2, characterized by the following features:

• 3.1 in which a first portion of the power that can be generated by the electric motors in generator operation is supplied to the internal combustion engine and
• 3.2 a second portion of the power generated by the electric motors in generator mode is fed into the hydrodynamic retarder.

4. The method according to any one of claims 1 to 3, characterized in that the fuel supply to the internal combustion engine during the Operating state it BRAKES is interrupted. 5. The method according to claim 3, characterized in that in Operating state BRAKES the internal combustion engine from Generator is decoupled. 6. The method according to claim 5, characterized in that the hydrodynamic retarders in the operating state BRAKES to the Main powertrain, d. H. at least the generator is coupled. 7. The method according to any one of claims 1 to 5, characterized in that that the hydrodynamic retarder in a branch to Main drive train is arranged and with this in the operating state BRAKES can be coupled. 8. The method according to claim 7, characterized in that the Secondary branch in the operating state BRAKES to the Main drive train is coupled.   9. The method according to any one of claims 6 to 8, characterized in that the hydrodynamic retarder by filling in the operating state BRAKES is switched on. 10. The method according to any one of claims 1 to 3, characterized by the following features:

• 10.1 in which the internal combustion engine is towed by the generator in the BRAKE operating state and
• 10.2 the second power component, which is determined from the total electrical power generated minus the power required for towing the internal combustion engine, is fed to the hydrodynamic retarder.

11. The method according to claim 10, characterized in that in Exhaust pipe of the individual cylinder / piston units a throttle valve is adjusted so that the exhaust pipe is closed. 12. The method according to any one of claims 10 or 11, characterized characterized in that the fuel supply for Internal combustion engine is interrupted. 13. The method according to any one of claims 10 to 12, characterized characterized in that a decompression valve in the cylinder head is provided for a certain period of time from shortly before up to approx. 90 to 120 ° KW after the compression TDC to drain the compressed air is opened from the combustion chamber. 14. Drive system for use in vehicles, in particular diesel-electric drive system, for carrying out the method according to claim 1,

• 14.1 with an electric motor driving at least one drive wheel at least indirectly;
• 14.2 with an internal combustion engine;
• 14.3 with an electrical machine that can be mechanically coupled to the internal combustion engine and operated as a generator in traction mode;
• 14.4 the electrical machine which can be operated as a generator and the electric motors are connected to one another via an electrical coupling; characterized by the following characteristic:
• 14.5 the electrical machine that can be operated as a generator can be coupled at least indirectly mechanically with at least one hydrodynamic retarder.

15. Drive system according to claim 14, characterized in that a further braking device from the engine brake Internal combustion engine is formed. 16. Drive system according to claim 15, characterized in that the individual cylinder / piston units of the internal combustion engine at least one decompression valve is assigned. 17. Drive system according to one of claims 14 to 16, characterized characterized in that the hydrodynamic retarder, based on the Direction of power flow in traction mode, before Internal combustion engine is arranged. 18. Drive system according to one of claims 14 to 17, characterized characterized in that the hydrodynamic retarder, based on the Direction of power flow in traction mode, the internal combustion engine is subordinate.   19. Drive system according to one of claims 14 to 18, characterized characterized in that the hydrodynamic retarder directly with the Crankshaft or the output shaft of the internal combustion engine or in the main powertrain, d. H. the connection between the Internal combustion engine and that can be operated as a generator electrical machine can be coupled. 20. Drive system according to one of claims 14 to 19, characterized characterized in that the hydrodynamic retarder parallel to Crankshaft or the main drive train is arranged. 21. Drive system according to claim 20, characterized in that the hydrodynamic retarders via a high drive with the crankshaft or the main drive train can be coupled. 22. Drive system according to one of claims 14 to 21, characterized by the following features:

• 22.1 the equipment of the retarder is oil;
• 22.2 a cooling circuit is assigned to the retarder;
• 22.3 the cooling circuit of the retarder is thermally coupled to a cooling circuit assigned to the internal combustion engine via a heat exchanger.

23. Drive system according to claim 22, characterized in that the Retarder resources the coolant of the Internal combustion engine is. 24. Drive system according to claim 23, characterized in that the Retarder circuit in series with the coolant circuit Internal combustion engine is arranged.   25. Drive system according to claim 23, characterized in that the Retarder working circuit in a branch to the coolant circuit the internal combustion engine is arranged.