Dedicated hybrid powertrain and method for controlling dedicated hybrid powertrain

Abstract

The invention relates to a dedicated hybrid drive train (1) of a motor vehicle, having a drive unit (4) consisting of a first electric machine (EM1) and an internal combustion engine (ICE), and a second electric machine (EM2), and a method for controlling the dedicated hybrid drive train, the drive unit (4) can be connected by means of a first disconnect clutch (C1) to a transmission (8) and the second electric machine (EM2) can be connected by means of a second disconnect clutch (C2) to the transmission, which is operatively connected to the drive wheels, and the energy accumulator (17) drives the electric machines (EM1, EM2) and can be charged by having the electric machines as a generator. In order to increase the performance and efficiency of the hybrid drive train (1), the transmission (8) has two thermal transmission stages (11, 12), which can be alternately connected by means of a first disconnect clutch (C1), and an electric transmission stage (9), which can be connected by means of a second disconnect clutch (C2), the hybrid drive train (1) is controlled as a function of a driver torque request, a state of charge of the energy accumulator (17) and a driving speed of the motor vehicle.

Description

Technical Field

[0001] The invention relates to a dedicated hybrid powertrain for a motor vehicle and a method for controlling the dedicated hybrid powertrain, the dedicated hybrid powertrain having a drive unit consisting of a first electric machine and an internal combustion engine and a second electric machine, wherein the drive unit can be connected to a transmission by means of a first disconnect clutch and the second electric machine can be connected to the transmission by means of a second disconnect clutch, the transmission being operatively connected to the drive wheels, and an energy accumulator driving the electric machine and being chargeable by the electric machine in generator operation.

[0002] The invention relates to a dedicated hybrid powertrain and a method for controlling a dedicated hybrid powertrain of a motor vehicle, the dedicated hybrid powertrain having a drive unit consisting of a first electric machine and an internal combustion engine and a second electric machine, wherein the drive unit can be connected to a transmission by means of a first disconnect clutch and the second electric machine can be connected to the transmission by means of a second disconnect clutch, the transmission being operatively connected to drive wheels and having at least one gear ratio, and an energy accumulator driving the electric machine and being chargeable by the electric machine in generator operation. Background Art

[0003] For example, a hybrid drive train with an internal combustion engine and two electric machines is known from publication DE 10 2018 103 245 A1. A drive unit for a hybrid drive train of a motor vehicle is disclosed, the drive unit having: an internal combustion engine; a first electric machine; a second electric machine, which is arranged so that its rotor is coaxial with the axis of rotation of the rotor of the first electric machine; a first transmission stage, which is arranged between a drive component which is non-rotatably coupled or can be coupled to an output shaft of the internal combustion engine and the first electric machine and / or a drive shaft of the electric machine; and a transmission subunit, via which the drive shaft of the respective electric machine is coupled or can be coupled to a wheel drive shaft.

[0004] Various transmission structures of hybrid powertrains are also known from the publications US 2016 / 0218584 A1, DE 11 2015006 071 T5, EP 331 372 A1 and WO 2019 / 101 264 A1.

[0005] The applicant's previously unpublished patent application DE 102021 111350.4, the entire contents of which are incorporated herein, also shows an embodiment of a hybrid powertrain having a drive unit consisting of an internal combustion engine and a first electric machine and a second electric machine, wherein the drive unit and the second electric machine can be connected to a transmission device by means of a disconnect clutch, which transmission device is operatively connected to the drive wheels and has at least one gear ratio.

[0006] Such hybrid powertrains are referred to as dedicated hybrid powertrains or dedicated hybrid transmissions (DHT). In these hybrid powertrains, the mechanical transmission part is simplified, for example by omitting the reverse gear, and at least one electric machine integrated into the transmission is used instead to provide the full range of functions. Dedicated hybrid transmissions can emerge from familiar transmission concepts, i.e. dual clutch transmissions, torque converter planetary transmissions, continuously variable transmissions (CVT) or automated manual transmissions. In this respect, the electric machine becomes part of the transmission, wherein its connection can be made on different drive shafts. In addition to parallel and / or series hybrid modes, one or more power distribution operating states can also be provided in conjunction with a planetary transmission.

[0007] The serial operating state of the hybrid powertrain is understood to mean that the internal combustion engine has no mechanical / torque-transmitting connection to the drive shaft / output shaft. The internal combustion engine drives a first electric machine, which is mainly used as a generator, which in turn supplies power to a second electric machine, which is mainly used as a traction motor / drive motor, or charges an energy accumulator. The drive shaft is driven by the second electric machine. The parallel hybrid mode is understood to mean that the internal combustion engine has a mechanical / torque-transmitting connection to the drive shaft / output shaft. The second electric machine can be in idling, boosted or recuperated operation.

[0008] Known methods for controlling dedicated hybrid powertrains only provide for serial operating states, in particular during starting, i.e. when the motor vehicle is slowly accelerated from a stop, wherein the energy accumulator can be discharged quickly during repeated starts at low driving speeds. Since the energy accumulator needs to be charged with the aid of the internal combustion engine, acoustic loads may occur for the occupants of the motor vehicle even during the period when the motor vehicle is at a standstill. Summary of the invention

[0009] The object of the invention is to further develop a dedicated hybrid powertrain and a method for operating a dedicated hybrid powertrain. In particular, the object of the invention is to enable a motor vehicle with a dedicated hybrid powertrain to be operated economically and with high performance and to ensure that the energy accumulator is charged and remains charged.

[0010] This object is achieved by the subject matter of claims 1 and 3. The claims dependent on claims 1 and 3 represent advantageous embodiments of the subject matter of claims 1 and 3, respectively.

[0011] The proposed dedicated hybrid powertrain has two drive sources, namely a drive unit with an internal combustion engine and a first electric machine connected to the internal combustion engine for drive purposes and a second electric machine, which can each be connected to the drive wheels by means of a disconnect clutch, such as a form-fitting clutch.

[0012] A transmission with a plurality of transmission ratios is arranged between the drive wheels close to the differential. In particular, two so-called thermal transmission stages with different transmission ratios are provided in this respect, which can be engaged alternatively by means of a first disconnect clutch and thus connect the drive wheels to the drive unit. The transmission stage is adapted to the available speed range of the internal combustion engine, so that the internal combustion engine or the drive unit can be used to drive the motor vehicle both at low and high driving speeds without an insert-type torque-balancing friction clutch. The disconnect clutch, which can be designed as a shift clutch with a shift sleeve, a sliding sleeve and a synchronizer ring, has, for example, three shift positions, each of which has an engaged connection of the thermal transmission stage between the output shaft of the drive shaft and the transmission output shaft of the transmission, and a neutral position, in which the drive unit is disconnected from the drive wheels.

[0013] Another so-called electric transmission stage of the transmission is used to adjust the speed range of the second electric machine, which can be integrated into the transmission, for example. A disconnect clutch, for example a shift clutch with a shift sleeve, a sliding sleeve and a synchronizer ring, has two shift positions and a neutral position, wherein in one shift position the rotor of the second electric machine is connected to the transmission output shaft, and in the neutral position the second electric machine is disconnected from the drive wheel. The individual gear ratios are engaged, for example, by means of a shift fork and a corresponding shift rail, a shift shaft, a shift drum, etc. and / or the like, by means of an automatic shift actuator, for example, which is hydraulically or electromechanically operated. The shift actuator can also actuate a parking lock of a motor vehicle, for example. Alternatively, at least one disconnect clutch can be designed as a dog clutch.

[0014] The electrical energy used to operate the electric machines is stored in an accumulator. One or both electric machines can be operated in generator operation in order to charge the accumulator. In this respect, the first electric machine can be driven by the internal combustion engine, while the second electric machine can generate electrical energy by recuperation.

[0015] In a preferred manner, in order to increase the performance of the motor vehicle, for example to increase the acceleration of the motor vehicle, for example in the range of 0 km / h to 100 km / h, to increase the agility of the motor vehicle and / or the like, an energy accumulator, for example a lithium-ion energy accumulator, is provided, which has a relatively high battery discharge power of more than 40 kW, preferably more than 60 kW and particularly preferably more than or equal to 100 kW for a dedicated hybrid drive train. In this regard, it has been shown that the advantages of the energy gain and energy efficiency of such an energy accumulator outweigh the disadvantages of the higher weight.

[0016] The proposed method is used to control a proposed dedicated hybrid powertrain. In a hybrid powertrain, the internal combustion engine, the electric machine and the disconnect clutch are usually controlled based on a driver torque request, which is specified by the driver, for example, by means of an accelerator pedal, the vehicle speed and the charge state of the accumulator. Other parameters, such as road surface conditions, for example the slope and curve of the road, road conditions in summer and winter driving, wheel-to-road grip and / or similar factors, braking action, external temperature and / or vehicle components, lighting conditions, traffic volume, etc., can be fully or partially integrated into the control of the hybrid powertrain, this does not necessarily mean an exhaustive list.

[0017] In this case, it has been shown to be advantageous that the use of two thermal transmission stages with a small transmission ratio and a large transmission ratio enables the internal combustion engine to be engaged earlier in certain driving situations without having to use the slip effect of the friction clutch, and at the same time enables individual engagement and neutral positions of the transmission stages to be achieved by means of a single positive-locking clutch. For example, in driving situations in which a motor vehicle often has to be started in a purely electric manner in serial operation, i.e., to accelerate from a standstill, if the energy accumulator is constantly discharged and is not sufficiently charged by the internal combustion engine or if the internal combustion engine causes a high noise level when the energy accumulator has to be recharged, the internal combustion engine can be engaged earlier due to the large underspeed transmission ratio of the first transmission stage, and the motor vehicle can be driven in parallel operation with the support of the internal combustion engine in the drive unit of the motor vehicle. In this regard, if necessary, the energy accumulator can be recharged at a lower speed of the internal combustion engine, thus resulting in less noise. With respect to the second transmission stage, with a significantly smaller underspeed transmission ratio or, depending on the subsequent ratio up to the drive wheels, with an overdrive ratio, it is still possible to drive at high driving speeds while maintaining a moderate speed of the internal combustion engine with the support of the drive unit or only in the case of the internal combustion engine.

[0018] In order to achieve economical and, where applicable, flexible operation of a motor vehicle with the proposed hybrid powertrain with two thermal transmission stages, various operating modes are controlled as a function of the driver torque request, the charge state of the energy accumulator and the driving speed. In a first operating mode, the motor vehicle is driven in series operation, in which the motor vehicle is driven purely electrically by the second electric machine and the internal combustion engine charges the energy accumulator with the aid of the first electric machine in generator operation. Series operation is used, for example, during starting, when the energy accumulator is not fully charged and at lower driving speeds. The second electric machine is operated in its most energy-efficient speed range. If rapid, moderate acceleration is required, the second electric machine can be operated in so-called boost operation by briefly operating the second electric machine at a higher speed than the most advantageous speed of the rotor and / or at a higher rated output, for example during overtaking maneuvers.

[0019] In the second operating mode, the motor vehicle is driven in parallel operation, in which the motor vehicle is driven by means of the drive unit with the first thermal transmission stage and the second electric machine selected. In this respect, at least a portion of the output of the internal combustion engine is provided to drive the motor vehicle. Another portion of the output can be used to charge the energy accumulator by operating the first electric machine in generator operation.

[0020] In the third operating mode, the motor vehicle is driven by means of the drive unit in parallel operation with the second thermal transmission stage and the second electric machine selected. The first electric machine can also be driven at least intermittently, in particular when the energy storage device is fully charged, and supports the drive of the motor vehicle, for example, when the driver has a high acceleration request or at a high driving speed.

[0021] In the fourth operating mode, the motor vehicle is driven solely by the internal combustion engine via the second gear ratio.

[0022] In so-called boost operation, for example when the driver demands high acceleration, the first and / or second electric machine can be briefly operated above its rated output in the respective operating mode during drive or motor operation of the corresponding electric machine.

[0023] In the fifth operating mode, the parking lock can be engaged when the motor vehicle is stationary. The parking lock can be actuated by a shift actuator for shifting / engaging a transmission stage and controlled by the software controlling the hybrid powertrain. In the fifth operating mode, the internal combustion engine can be switched off or started if necessary, depending on the charge state of the energy accumulator, either by the driver, in order to charge the energy accumulator when the motor vehicle is stationary by means of the first electric machine driven by the internal combustion engine in generator operation.

[0024] In a sixth operating mode, when the drive unit is decoupled from the transmission and the motor vehicle is moving, kinetic energy of the motor vehicle can be recovered by charging the energy accumulator by means of the second electrical machine driven by the drive wheels in generator operation.

[0025] In the seventh operating mode, the motor vehicle can be driven in reverse in series or purely electric operation by reversing the direction of rotation of the second electric machine, so that a mechanically implemented reverse gear can be omitted and production costs and manufacturing effort can be reduced accordingly.

[0026] It will be appreciated that, in particular in noise-regulated inner city areas etc., the motor vehicle can be driven purely electrically in the eighth operating mode by means of the second electric machine with the drive unit disconnected and the internal combustion engine switched off, if the charge state of the energy accumulator is sufficient.

[0027] Different operating modes are applied depending on the state of charge of the accumulator. For this purpose, the state of charge is divided into several state of charge ranges, within which different operating modes are set depending on the driver torque request and the current driving speed. For example, the state of charge is divided into the following ranges: within this range, conventional operation of the hybrid powertrain is not expected, such as a very low state of charge of, for example, a residual charge of less than 10% to 20% of the maximum charge capacity or a charge of more than 80% of the maximum charge capacity. These charge limit states are preferably set only in emergency situations when there is a risk of the motor vehicle being stranded or the accumulator being damaged due to accidental overcharging. Between these, for example, three generally available state of charge ranges can be distinguished, such as a high state of charge with a charge capacity of 41% to 80% of the maximum charge, a medium state of charge with a maximum charge of 26% to 40% and a low state of charge with a maximum charge of 11% to 25% of 100%. It should be understood that the limits of the state of charge as well as the current capacity, temperature and / or other variables that permanently or sharply affect the quality of the accumulator can be adapted to the motor vehicle according to the situation and can be adapted continuously, for example, according to age, expected service life, etc. In each range, the mode is set according to the driver torque request, for example, wherein, for example, when the driver torque request is currently high, the electric machine or two electric machines and the possible internal combustion engine currently used for the driving operation are operated in boost operation, i.e. briefly in an output range above the rated output. Alternatively, the mode can be changed, and, for example, one electric machine and / or the internal combustion engine can be engaged. For example, a typical, adapted driver torque request and its development over time can be taken into account. In each state of charge range, the operating mode is also set according to the driving speed of the motor vehicle, for example to compensate for the driving resistance that increases with the driving speed. Since there is no friction clutch between the internal combustion engine and the drive wheels, only the first operating mode, the seventh operating mode and the eighth operating mode are used for starting and reversing, wherein the operating mode one and the operating mode seven are boosted by the second electric machine when necessary. When the synchronous speed is reached between the lowest available driving speed of the internal combustion engine and the transmission output shaft in the first thermal transmission stage, the second operating mode can be engaged and utilized from a predetermined driving speed for parallel operation of the hybrid powertrain. At high driving speeds, for example, the third operating mode can be engaged with the second thermal transmission stage. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Reference Figures 1 to 8 The exemplary embodiments shown in the drawings illustrate the present invention in more detail. In the drawings:

[0029] Figure 1 shows a schematic diagram of a dedicated hybrid powertrain,

[0030] Figure 2 Shows Figure 1 A table showing various operating modes of a hybrid powertrain and engagement / disengagement of powertrain components,

[0031] Figure 3 The shift actuator is shown in FIG. Figure 2 a shift diagram of a hybrid powertrain during driving operation of a motor vehicle,

[0032] Figure 4 It is shown that in the case of a low state of charge of the accumulator, the wheel torque varies with Figure 1 A diagram of the driving speed variation of a hybrid powertrain motor vehicle,

[0033] Figure 5 The wheel torque is shown as a function of the charge state of the accumulator at a medium level. Figure 1 A diagram of the driving speed variation of a hybrid powertrain motor vehicle,

[0034] Figure 6 It is shown that the wheel torque varies with the charge state of the accumulator. Figure 1 A diagram of the driving speed variation of a hybrid powertrain motor vehicle,

[0035] Figure 7 shows that the wheel torque varies with Figure 1 A diagram of a driving speed variation of a motor vehicle having a hybrid powertrain having an accumulator with a low discharge power, and

[0036] Figure 8 shows that the wheel torque varies with Figure 1 Graph of the driving speed profile of a motor vehicle with a hybrid power train having an energy accumulator with a high discharge power. DETAILED DESCRIPTION

[0037] Figure 1A schematic diagram of a hybrid drive train 1 provided for a hybrid drive of a motor vehicle is shown. The hybrid drive train 1 comprises a drive unit 4 consisting of an internal combustion engine ICE with a crankshaft 2 and a first electric machine EM1 with a rotor 3 and a second electric machine EM2 with a rotor 5 for driving the motor vehicle. The drive unit 4 can be coupled to a transmission 8 by means of a first disconnecting clutch C1 and the second electric machine EM2 can be coupled to the transmission 8 by means of a second disconnecting clutch C2. The two disconnecting clutches C1, C2 are designed here as form-fitting clutches 6, 7, which are actuated by an actuator (not shown), such as a shift actuator, which also engages and disengages with a parking lock (not shown). The transmission 8 comprises a single electric transmission stage 9 between the second electric machine EM2 and the transmission output shaft 10 and two thermal transmission stages 11, 12 between the drive unit 4 and the transmission output shaft 10. The two transmission stages 11, 12 and a neutral position for disconnecting the drive unit 4 from the transmission output shaft 10 are engaged by means of the disconnecting clutch C1. An output transmission ratio 14 of the transmission 8 is provided between the transmission output shaft 10 and the differential 13, wherein the gears of the transmission stage 12 are formed as fixed gears relative to the transmission output shaft 10 and at the same time form the gears of the transmission output shaft 10 of the output gear mechanism. The differential 13 branches off to drive shafts 15, 16, such as cardan shafts and hubs of drive wheels (not shown).

[0038] The electric machines EM1, EM2 and the actuators are electrically connected to the energy accumulator 17 by means of a control unit and power electronics not shown. Depending on the operating state of the motor vehicle, the charge state of the energy accumulator 17 and the load request from the driver and / or an autonomous control system of the motor vehicle, the wheel torque on the drive wheels is adjusted according to Figure 2 The operating mode of the hybrid powertrain 1 described in Figures 4 to 6 It will be appreciated that, depending on the design of the hybrid powertrain and the requirements of the motor vehicle, fewer or more operating modes and / or ranges for subdividing the state of charge of the accumulator may be provided.

[0039] Figure 2 Shows and controls Figure 1 Table 18 relating to a hybrid powertrain having set operating modes MOD1 to MOD8 and the activation state of the parking lock PS, the disconnect clutch C1 ( Figure 1) and the relationship between the shift states C1(1), C1(2), the electric machines EM1, EM2 and the internal combustion engine ICE. Here, the character X indicates the actuation of the disconnect clutch C1, C2 or the actuation of the first transmission stage by means of the shift state C1(1) and the actuation of the second transmission stage by means of the shift state C1(2) and the actuation of the parking lock PS. Conversely, the character 0 refers to the disconnected engagement position of these elements. The + symbol indicates that the electric machines EM1, EM2 and the internal combustion engine ICE are activated, while the - symbol indicates that they are not activated.

[0040] The first operating mode MOD1 is a serial operation of the hybrid powertrain in which the motor vehicle is driven electrically only by means of the electric machine EM2 when the parking lock is released and the internal combustion engine drives the electric machine EM1 in order to provide electrical energy to the second electric machine EM2 and, if applicable, to charge the energy accumulator in the case of excess energy. In the first operating mode MOD1, the electric machine EM2 can also be operated at least for a short time in a boost operation above its rated output. The disconnect clutch C1 is here set to a neutral position, i.e. neither the shift state C1(1) nor the shift state C1(2) is activated, so that no torque is transmitted from the drive unit comprising the internal combustion engine ICE and the electric machine EM1 to the transmission and thus to the drive wheels.

[0041] In the second operating mode MOD2, the hybrid powertrain uses a first thermal transmission stage with a smaller overdrive ratio to operate in parallel and therefore at a lower driving speed of the motor vehicle. Here, the shift state C1 (1) of the disconnect clutch C1 is engaged, so that torque is transmitted to the drive wheels in parallel from the internal combustion engine ICE and the second electric machine EM2. The second electric machine EM2 can be powered by the accumulator alone, or by the electric machine EM1 in generator operation, or by both. In order to provide boost operation, the electric machine EM2 can be operated in a manner higher than its rated output and / or the electric machine EM1 can be operated in a motor-driven manner and support the internal combustion engine ICE, which can be operated at an output that temporarily exceeds the rated output if necessary. Here, the parking lock PS is disengaged and the disconnect clutch C2 is engaged.

[0042] In contrast to the operating mode MOD2, the hybrid drive train is operated in the operating mode MOD3 as a drive in a second, thermal transmission stage with a greater overdrive ratio in parallel operation by means of the engaged shift state C1 (2) of the disconnect clutch C1. The torque is accordingly transmitted to the drive wheels by means of the internal combustion engine ICE and, if necessary, by means of the electric machines EM1 and EM2. In accordance with the operating mode MOD2, the disconnect clutch C2 is engaged and the parking lock is disengaged. The transmission ratio of the second transmission stage proceeds from the first transmission stage and is designed to achieve the maximum speed of the motor vehicle.

[0043] In operating mode MOD4, for example, when the charge state of the energy accumulator is low, the motor vehicle can be driven only by the internal combustion engine. In this respect, the first electric machine EM1 can also be operated in generator operation to charge the energy accumulator. The second electric machine EM2 is switched off and the disconnect clutch C2 is disengaged. The disconnect clutch C1 engages the second thermal transmission stage by means of the shift state C1 (2).

[0044] The operating modes MOD5, MOD5a control the stationary state of the motor vehicle with the drive unit disconnected by means of the disconnect clutch C1 in the neutral position, the disconnect clutch C2 engaged and the electric machine EM2 switched off and the parking lock PS activated. In the operating mode MOD5, the drive unit with the internal combustion engine ICE and the first electric machine EM1 is also switched off. In the operating mode MOD5a, the energy accumulator is charged with the motor vehicle stationary by the internal combustion engine ICE driving the electric machine EM1 operated in generator operation.

[0045] The operating mode MOD6 is provided for recovering kinetic energy as electrical energy, for example, when the motor vehicle is decelerating. When the parking lock PS is disengaged and the disconnect clutch C1 is in the neutral position, the disconnect clutch C2 is engaged. The electric machine EM2 operates in generator operation and charges the energy accumulator when the motor vehicle is decelerating.

[0046] The operating modes MOD7 and MOD8 are provided for purely electric driving. For this purpose, the parking lock PS is decoupled and the disconnect clutch C1 is in a neutral position, wherein the shift states C1(1), C1(2) are deactivated. In the operating mode MOD8, the disconnect clutch C2 is engaged and the motor drives the motor vehicle forward, for example in a noise regulation zone or an emission restriction zone, and drives the motor vehicle backward when the direction of rotation of the electric motor EM2 is reversed. In the operating mode MOD7, the drive unit with the internal combustion engine ICE and the electric motor EM1 is switched off during electric forward travel. In particular, when the charge state of the energy accumulator is low, charging of the energy accumulator can be provided during reverse travel of the motor vehicle in the operating mode MOD8 by means of the internal combustion engine ICE and the electric motor EM1 operated in generator operation.

[0047] Figure 3 Shows Figure 1A modeled shift sequence 100 of a shift actuator of a transmission 8 over time t, wherein a shift characteristic 101 of a disconnect clutch C2 has shift states of disconnection and engagement. A shift characteristic 102 shows shift states C1(1), C1(2) and shift states disconnection and engagement. A shift characteristic 103 shows shift states of disconnection and engagement of a parking lock PS. According to the illustration, the shift sequence can be provided in the form of an axially actuated shift drum, wherein the disconnect clutches C1, C2 and the cam followers of the parking lock PS are arranged in the associated shift characteristics 101, 102, 103, which shift characteristics cause corresponding sliding sleeves, shift sleeves and / or the like to shift when the shift drum is axially displaced for setting the shift states disconnection and engagement, engagement, C1(2), C1(2).

[0048] In Figure 100, Figure 2 The operating modes MOD5 / MOD5a, MOD1, MOD2, MOD3, MOD4, MOD3, MOD2, MOD1, MOD5 / MOD5a are set in chronological order according to a model-like start of the motor vehicle in the case of acceleration to maximum speed and return to standstill. At standstill according to operating mode MOD5 or MOD5a, the parking lock PS is engaged and the two disconnect clutches C1, C2 are disengaged. The start is performed in operating mode MOD1 with serial operation of the hybrid powertrain. For this purpose, the parking lock PS is disengaged and the disconnect clutch C2 is engaged. During the transition to operating mode MOD2, which corresponds to parallel operation, the internal combustion engine is engaged by shifting the disconnect clutch C1 to shift state C1 (1). During the transition from operating mode MOD2 to operating mode MOD3, which is intended for higher driving speeds and corresponds to parallel operation of the hybrid powertrain, the disconnect clutch C1 is shifted from shift state C1 (1) to shift state C1 (2). In operating mode MOD4 , disconnect clutch C2 is disengaged, with operation solely by means of the internal combustion engine ICE. The motor vehicle is brought to a standstill in the reverse order.

[0049] Figure 4 The wheel torque M applied to the drive wheels is shown as a function of the driving speed v from zero to a value having a low charge state of the energy storage device 17, for example less than or equal to 25% of the maximum charge capacity. Figure 1 Graph 200 of the variation of the maximum speed v(max) of a motor vehicle of a hybrid powertrain 1 of FIG. Curves 201 , 202 indicate the wheel loads acting on the drive wheels on a flat road (curve 201 ) and on a road with a 4% gradient (curve 202 ).

[0050] The operation of the motor vehicle and the hybrid powertrain 1 shown is carried out according to operating modes MOD1, MOD2, MOD3. The motor vehicle is only electrically started using operating mode MOD1 with a starting torque M1, wherein the electrical energy is provided only by the drive unit 4. At a driving speed v1 of, for example, 20 km / h to 25 km / h, the speed of the drive wheels is sufficient so that the internal combustion engine ICE can be engaged by means of the first thermal transmission stage 11 of operating mode MOD2. When a driving speed v2 of, for example, 50 km / h is reached, the second transmission stage 12 can be engaged in operating mode MOD3. Between driving speeds v1 and v2, the motor vehicle can be operated in operating mode MOD2 or MOD3, depending on the driver torque request or environmental requirements.

[0051] Figure 5 The wheel torque M applied to the drive wheels is shown as a function of the driving speed v from zero to a value of 100 at a medium charge state of the energy storage device 17, for example 26% to 40% of the maximum charge capacity. Figure 1 Graph 300 of the variation of the maximum speed v(max) of a motor vehicle of a hybrid powertrain 1 of FIG. Curves 301 , 302 indicate the wheel loads acting on the drive wheels on a flat road (curve 301 ) and on a road with a 4% gradient (curve 302 ).

[0052] According to Figure 4 The diagram 200 can be different operating modes set at low charge states, in addition to the operating modes MOD1, MOD2, MOD3 that contribute to the wheel torque M, the electric machines EM1, EM2 are available through the accumulator 17 due to the higher charge state of the accumulator. The motor vehicle starts up to the driving speed v1 with the starting torque M1 using the operating mode MOD1. In addition to or in addition to the operating mode MOD1, an operating mode MOD2 or a modified operating mode MOD2 with a first thermal transmission stage is available at driving speeds above v1, depending on, for example, the driver torque request, in which operating mode the electric machine EM1 is operated in motor operation and draws the associated electrical energy from the accumulator 17. Alternatively or additionally, an operating mode MOD1+ can be provided, in which, in addition to the electrical energy provided by the electric machine 1, the electric machine EM2 is also supplied by the accumulator. In addition to the operating mode MOD3, an operating mode MOD3+ can also be set according to the driving speed v2, in which operating mode the electric machine EM1 is used for motor operation in the second thermal transmission stage 12 in addition to the internal combustion engine ICE.

[0053] Figure 6 The wheel torque M applied to the drive wheel is shown as a function of the driving speed v from zero to a value having a high charge state of the energy storage device 17, for example, greater than 40% of the maximum charge capacity. Figure 1Graph 400 of the variation of the maximum speed v(max) of a motor vehicle of a hybrid powertrain 1 of FIG. Curves 401 , 402 indicate the wheel loads acting on the drive wheels on a flat road (curve 401 ) and on a road with a 4% gradient (curve 402 ).

[0054] Due to the high state of charge of the accumulator 17, Figure 5 Compared to the operating modes MOD1, MOD1+, MOD2, MOD2+, MOD3, MOD3+ in the medium charge state, additional operating modes are available. In the operating mode MOD1P, the electric machine EM2 is operated at an output higher than the rated output. In the operating mode MOD1C, the motor vehicle is started using the electric machine EM2, wherein electrical energy is drawn from the energy storage device 17.

[0055] Figure 7 and Figure 8 Shows Figure 1 The hybrid powertrain 1 in FIG. 5 has energy accumulators 17 with different discharge capacities, each of which has a high state of charge. Graphs 500 and 600 each show the state of charge of the energy accumulator 17 as the driving speed v changes from zero until the selected operating mode MOD1, MOD1P, MOD2+, MOD3+ (see FIG. Figure 5 and Figure 6 ) with a maximum speed v(max) varying wheel torque, wherein the discharge capacity of the energy accumulator is utilized to a particularly high extent. The motor vehicle is started using operating mode MOD1 with a starting torque M1. Figure 7 An accumulator with a discharge capacity of 100 kW is shown, Figure 8 The behavior of an accumulator with a discharge capacity of 100 kW is shown. At the same ratio of the wheel torque M, the operating mode MOD2+ of the accumulator with a discharge capacity of 40 kW allows a significantly higher wheel torque to be obtained from a driving speed above v1. The operating mode MOD1P can contribute to the wheel torque at a much lower driving speed v; for accumulators with a higher discharge capacity, the torque contribution of the operating modes MOD1, MOD3+ also increases, so that in order to provide a more agile driving performance of the motor vehicle, an accumulator with a higher discharge capacity may be advantageous despite higher production costs and weight.

[0056] Reference numerals list

[0057] 1 Hybrid Powertrain

[0058] 2 Crankshaft

[0059] 3 Rotor

[0060] 4 Drivers

[0061] 5 Rotor

[0062] 6 Positive-lock clutch

[0063] 7 Form-fitting clutch

[0064] 8 Transmission

[0065] 9 transmission stages

[0066] 10 Transmission output shaft

[0067] 11 gear stages

[0068] 12 gear stages

[0069] 13 Differential

[0070] 14 Output gear ratio

[0071] 15 Drive shaft

[0072] 16 Drive shaft

[0073] 17 Accumulator

[0074] 18 Form

[0075] 100 Gear shift sequence

[0076] 101 Gear Shift Characteristics

[0077] 102 Gear Shift Characteristics

[0078] 103 Gear shifting characteristics

[0079] 200 images

[0080] 201 Curve

[0081] 202 Curve

[0082] 300 images

[0083] 301 Curve

[0084] 302 Curve

[0085] 400 images

[0086] 401 Curve

[0087] 402 Curve

[0088] 500 images

[0089] 600 images

[0090] C1 disconnect clutch

[0091] C1(1) Shift status

[0092] C1(2) Shift status

[0093] C2 disconnect clutch

[0094] EM1 motor

[0095] EM2 motor

[0096] ICE Internal Combustion Engine

[0097] M wheel torque

[0098] M1 Starting torque

[0099] MOD1 Operation Mode

[0100] MOD1+ Operation Mode

[0101] MOD1P Operation Modes

[0102] MOD1C Operation Modes

[0103] MOD2 Operation Mode

[0104] MOD2+ Operation Mode

[0105] MOD3 Operation Mode

[0106] MOD3+ Operation Mode

[0107] MOD4 Operation Mode

[0108] MOD4+ Operation Mode

[0109] MOD5 Operation Mode

[0110] MOD5a Operation Modes

[0111] MOD6 Operation Mode

[0112] MOD7 Operation Mode

[0113] MOD8 Operation Mode

[0114] PS parking lock

[0115] t time

[0116] v Driving speed

[0117] v1 Driving speed

[0118] v2 Driving speed

[0119] v(max) maximum speed.

Claims

1. A dedicated hybrid powertrain (1) for a motor vehicle, comprising a drive unit (4) consisting of a first electric machine (EM1) and an internal combustion engine (ICE) and a second electric machine (EM2), wherein: The drive unit (4) can be connected to a transmission (8) by means of a first disconnect clutch (C1) and the second electric machine (EM2) can be connected to the transmission by means of a second disconnect clutch (C2), the transmission is operatively connected to the drive wheels, and an energy accumulator (17) drives the electric machines (EM1, EM2) at least intermittently and can be charged by the electric machines in generator operation, characterized in that the transmission (8) has two thermal transmission stages (11, 12) that can be alternately engaged by means of the first disconnect clutch (C1) and an electric transmission stage (9) that can be engaged by means of the second disconnect clutch (C2).

2. The dedicated hybrid powertrain (1) according to claim 1, characterized in that The energy storage device (17) has a discharge capacity of more than 40 kW.

3. A method for controlling a dedicated hybrid powertrain (1) according to claim 1 or 2, characterized in that A first operating mode (MOD1), a second operating mode (MOD2) and a third operating mode (MOD3) are provided, in which the motor vehicle is driven in series by means of the second electric machine (EM2) and the energy accumulator is charged by means of the internal combustion engine (ICE) through the generator operation of the first electric machine (EM1), in which the motor vehicle is driven in parallel by means of the drive unit (4) with the first thermal transmission stage (11) and the second electric machine (EM2) selected, and in which the motor vehicle is driven in parallel by means of the drive unit (4) with the second thermal transmission stage (12) and the second electric machine (EM2) selected, wherein the wheel torque (M) applied to the drive wheels is set based on the components of the operating modes (MOD1, MOD2, MOD3) according to the driver torque request, the charge state of the energy accumulator (17) and the driving speed (v) of the motor vehicle.

4. The method according to claim 3, characterized in that In a fourth operating mode (MOD4), the drive unit (4) is used only to drive the motor vehicle.

5. The method according to claim 3 or 4, characterized in that: In at least one operating mode (MOD1, MOD2, MOD3), the first electric machine is operated in motor operation or generator operation.

6. The method according to any one of claims 3 to 5, characterized in that At least one electric machine (EM1, EM2) is operated at least temporarily above its rated output.

7. The method according to any one of claims 3 to 5, characterized in that When the motor vehicle is stationary, the parking lock (PS) is engaged in a fifth operating mode, wherein, depending on the charge state of the energy accumulator (17), the energy accumulator (17) is charged by means of the first electric machine (EM1) driven by the internal combustion engine in generator operation.

8. The method according to any one of claims 3 to 7, characterized in that In a sixth operating mode (MOD6), with the drive unit (4) decoupled from the transmission and the motor vehicle moving, the energy accumulator (17) is charged by means of the second electric machine (EM2) driven by the drive wheel in generator operation.

9. The method according to any one of claims 3 to 8, characterized in that In a seventh operating mode (MOD7), the motor vehicle is driven purely electrically by means of the second electric machine (EM2) with the drive unit (4) decoupled and the internal combustion engine (ICE) switched off.

10. The method according to any one of claims 3 to 9, characterized in that In an eighth operating mode (MOD8), the motor vehicle is driven in reverse in series operation by reversing the direction of rotation of the second electric machine (EM2).

Images