Hybrid drive

Abstract

Hybrid drive (1) for motor vehicles for passenger vehicles, with - an internal combustion engine (2), - an electric machine (3), and - a torque superposition device (4) by means of which a torque supplied by the internal combustion engine (2) can be superimposed with a torque supplied by the electric machine (3), wherein the torque superposition device (4) has a first and a second torque input (12, 8) and a torque output (16a) as well as a first transmission device (13, 14) and a second transmission device (5, 6, 7), and the electric machine (3) can be coupled to the first torque input (12) and the internal combustion engine (2) to the second torque input (8), wherein the first torque input (12) is connected to the first transmission device (13, 14) and the second torque input (8) is connected to the second transmission device (5, 6, 7), and the transmission devices (5, 6, 7; 13, 14) are each coupled to the torque output on the output side, characterized by the fact that the second translation device has exactly two alternatively selectable translation levels (5, 6) and the first translation device has at least two alternatively selectable translation levels (5, 6, 7; 13, 14) and where • a clutch (K0) that can be switched into a slip state is provided, by means of which torque can be transferred from the first torque input (12) to the second torque input (8), or vice versa, and • the clutch (K0) is arranged between the two torque inputs (8, 12), wherein the two torque inputs (8, 12) can be brought to the same rotational speed by closing the clutch • and where the peak power of the electric motor is at least 30% of the rated power of the internal combustion engine.

Description

[0001] The present invention relates to a hybrid drive according to the features of patent claim 1.

[0002] Such a hybrid drive is known from FR 2 811 395 A1. Relevant prior art also includes US 2005 / 0 032 598 A1, DE 10 2005 002 591 A1, DE 10 2010 030 569 A1 (post-published), DE 102 03 514 A1, and WO 2010 / 070 707 A1. Furthermore, DE 101 33 695 A1 discloses a transmission for a motor vehicle.

[0003] In many hybrid concepts known from the prior art, the crankshaft of an internal combustion engine is connected to the rotor of an electric motor via a first clutch and to the input shaft of a multi-speed automatic transmission via a second clutch. In "parallel operating mode," i.e., when the vehicle is driven simultaneously by the internal combustion engine and the electric motor, the internal combustion engine and the electric motor thus rotate at the same speed or, if coupled via a "transmission ratio," according to a predetermined speed ratio, which is not always optimal in terms of energy efficiency.

[0004] The object of the invention is to create a novel hybrid drive concept that better takes into account the disadvantages of conventional hybrid drive concepts described above.

[0005] This object is achieved by the features of patent claim 1. Advantageous embodiments and further developments of the invention can be found in the subclaims.

[0006] The starting point of the invention is a hybrid drive with a first drive motor, which can be formed by an electric motor, and a second drive motor, which can be formed by an internal combustion engine. The two drive motors are coupled to one another via a "torque superposition device." The term "torque superposition device" is to be interpreted very broadly. It means, in very general terms, that the drive power of the two drive motors or the respective drive torques can be "connected together," i.e., superimposed, e.g., by means of a summing gear.The torque superposition device accordingly has a first torque input, which is assigned to the first drive machine, and a second torque input, which is assigned to the second drive machine, as well as a torque output, via which the "interconnected" torque can be transmitted to drive wheels of a vehicle.

[0007] In the following, the term “electric machine” or “electric motor” is used for the first drive machine and the term “combustion engine” is used for the second drive machine, although this is not to be understood as restrictive.

[0008] The core of the invention is that the electric machine is coupled or can be coupled via the first torque input to a "first transmission device" and the internal combustion engine is coupled or can be coupled via the second torque input to a "second transmission device" of the torque superposition device, and the transmission devices are each coupled on the output side to the torque output, i.e. are kinematically connected, and that a clutch that can be switched into a slip state is provided, by means of which torque can be transferred from the first torque input to the second torque input, or vice versa. The second transmission device has exactly two alternatively selectable transmission stages, and the first transmission device has at least two alternatively selectable transmission stages. In principle, various designs are possible for the transmission devices, such as, for example:switchable spur gear stages, switchable planetary gears, switchable belt or chain drives, etc., or even continuously switchable transmission devices.

[0009] The clutch is located between the two torque inputs, allowing both torque inputs to be brought to the same speed by engaging the clutch. The peak power of the electric motor is at least 30% of the rated power of the combustion engine.

[0010] With the hybrid drive according to the invention, the two "power branches" can be switched independently of each other. Within the available gears, the speeds of the combustion engine and the electric motor can be selected independently of each other. The power branch not affected by the shift supports the tractive force at the torque output of the torque superposition device with its full power during the shift. The power branch affected by the shift, or the relevant drive unit (electric motor or combustion engine), can be used for "external synchronization" of the shift.

[0011] In other words, in contrast to conventional parallel hybrid concepts, the advantage is that the electric motor and the combustion engine in parallel hybrid operation do not always have to rotate at a specific, fixed speed ratio, but that at least one of the two drive motors can be "shifted into another gear", which is not only advantageous from a consumption point of view, but also gives the drive better dynamics.

[0012] The above-mentioned clutch, by means of which torque can be transferred from the first torque input to the second torque input, or vice versa, enables load shifts, i.e. switching of the transmission devices without interruption of traction, both in purely electric motor operating mode (vehicle is only driven by the electric machine) and in mixed operation (vehicle is simultaneously driven by the combustion engine and the electric machine), which is explained in more detail below in connection with the drawing.

[0013] The two gear ratios of the second gear ratio system are designed, for example, so that one gear ratio is configured as a top-speed gear and another as an efficiency gear. The top-speed gear allows the vehicle to reach its maximum speed. The efficiency gear, on the other hand, is designed longer than the top-speed gear and thus enables efficient operation of the combustion engine in the medium and higher speed ranges, for example, on country roads or highways.

[0014] If the second transmission is limited to two gear ratios designed in this way, the first transmission ratio of the electric motor and also the power of the electric motor must be designed such that the vehicle's operation during start-up and at lower speeds, i.e., particularly in urban driving, is essentially electric. The combustion engine generally provides support here at most by providing a base load.

[0015] A hybrid drive according to the invention, limited to two gear ratios of the second gear ratio device, is suitable for highly electrified drives with higher electrical power, i.e., the peak power of the electric motor is at least 30%, preferably at least 50% of the rated power of the combustion engine, better 80%, and ideally at least 100%. The continuous power of the electric motor can be approximately half the peak power, in the ratio typical for electric motors.

[0016] The more balanced the power ratio between the electric motor's peak power and the combustion engine's rated power, the better the electric motor can meet dynamic load requirements, especially during acceleration. The drive units can also support each other, especially during gear changes, enabling very smooth gearshifts with little or no loss of traction during the shift.

[0017] It is particularly advantageous if the power ratio between the continuous power of the electric motor and the rated power of the combustion engine is approximately balanced or exceeds the rated power of the combustion engine, i.e. the continuous power of the electric motor is approximately 80% of the rated power of the combustion engine or more. In this case, the electric motor can provide the propulsion power even in those driving situations in which the drive gear of the combustion engine cannot yet be operated or can only be operated with low power - thus with a torque superposition device designed according to the invention with, for example, only two combustion engine gears designed as described above when starting off and in the lowest speed range up to approximately 30 km / h - and can thus perform the driving function purely or predominantly by electric motor without the driving performance being restricted.

[0018] If the electric motor's peak power were lower than the minimum power requirement specified above, the electric motor could no longer perform a fully functional driving function, but could at best support the driving mode of the combustion engine (so-called "assist"). This would make it impossible to achieve the inventive reduction of the currently common six or more combustion engine gears to a few gears, with the advantages of the invention mentioned here.

[0019] Due to the small number of transmission stages of the second transmission device, the component-side effort is low and, in particular, the installation space requirements are also low.

[0020] It is particularly advantageous that the first transmission device is designed with at least two alternatively selectable transmission stages.

[0021] The "longer" gear ratio should preferably be configured as the vehicle's top-speed gear. This offers the advantage that the shorter gear ratio can be used as a dynamic gear with the excellent torque delivery typical of electric motors, whereas the longer gear ratio allows the electric motor to remain connected even at high speeds up to the vehicle's top speed, thus allowing it to be used for both braking energy recovery and boosting.

[0022] According to a further development of the invention, the hybrid drive has a single electric motor designed to generate vehicle propulsion, which enables a comparatively simple and compact, and especially cost-effective, design. This naturally also includes solutions in which, for example, another electric motor is integrated into the system, for starting the combustion engine, but this electric motor is then not used to generate propulsion.

[0023] According to an advantageous development of the invention, the torque output of the torque superposition device is designed as an output shaft with an output gear stage, wherein the output gear stage is preferably directly connected to the differential of the driven vehicle axle of the motor vehicle.

[0024] Positive or frictional "shifting elements" can be provided to select the individual gear ratios of the transmission devices. For example, shift sleeves can be provided for spur gear stages. To improve shifting comfort, a synchronization device can be assigned to one of the positive shifting elements or to all of the positive shifting elements. Since "external" pre-synchronization is already possible with the combustion engine or the electric motor, simpler, cost-effective shifting elements can also be used, such as sliding sleeves with dog clutches without synchronization units, as are known, for example, from motorcycle transmissions. "External synchronization" can be achieved by appropriate speed control of the combustion engine or the electric motor.

[0025] If planetary gears are used as transmission devices, friction clutches or friction brakes are particularly suitable as switching elements. In principle, however, friction-locking switching elements could also be used for switchable spur gear stages.

[0026] Decoupling the electric motor or combustion engine from the torque superimposition device is very easy by switching the relevant switching element(s) to the "neutral position." The term "neutral position" refers to a position in which no torque can be transferred from the electric motor or combustion engine to the torque superimposition device. This enables both a purely electric drive and the decoupling of the combustion engine to reduce drag torque, or a purely combustion engine drive with the electric motor decoupled.

[0027] A clutch (disconnect clutch) can be arranged between the crankshaft of the internal combustion engine and the second torque input of the torque superposition device. By opening the disconnect clutch, the internal combustion engine can be completely decoupled and, if necessary, switched off, which is particularly advantageous when the vehicle is operating purely electric.

[0028] In summary, the invention achieves the following advantages in particular: - The independent switchability of the two power branches enables mutual traction support. This increases comfort compared to conventional hybrid concepts, in which an engaged transmission gear is always "imprinted" on both power branches. - The hybrid concept according to the invention allows free scalability of the drive units and is therefore not only suitable for conventional hybrid concepts, but also in particular for so-called plug-in hybrid concepts. - The independent selection of the operating points for the combustion engine and the electric motor opens up great potential for reducing consumption and emissions, improving drive acoustics and increasing driving performance. - The "summing function" of the torque superposition device allows the combustion engine and the electric motor to optimally complement each other during operation. This creates savings and efficiency potential, which in turn enables a "scaling down" of the two drive units. "Scaling down" means that, unlike conventional hybrid concepts, the electric motor no longer has to meet the highest efficiency requirements across the entire speed range. - With the hybrid drive according to the invention, mixed operation can be optionally carried out during driving, ie both drive units are engaged and deliver positive (driving) or negative (only applies to electric motor in generator mode) torque depending on the driving situation, or purely electric operation in the sense of an e-driving function.

[0029] The invention is explained in more detail below in conjunction with the drawings. They show: Fig. 1 the basic principle of the invention in a schematic representation; Fig. 2 that in Fig. 1 shown concept with an additional intermediate shaft; Fig. 3 shows a further embodiment of a hybrid drive; and Fig. 4 the embodiment of the Fig. 2 with two additional couplings.

[0030] Fig. 1 shows a basic principle diagram of a hybrid drive 1 according to the invention with an internal combustion engine 2, an electric machine 3 and a torque superposition device 4. In Fig. 1 Not shown are the housings of the components, actuators, oil supplies for lubrication of bearings and the like.

[0031] The torque superposition device 4 designed as a summing gear in Fig. 1 has a first torque input 12, a second torque input 8, a torque output 16a and 16b, as well as a first transmission device comprising two transmission stages 13 and 14, and a second transmission device comprising three transmission stages 5, 6, and 7. The torque inputs 8 and 12 are each designed as input shafts. The rotor shaft of the electric machine 3 is coupled to the first torque input 12 of the torque superimposition device 4, and the crankshaft of the internal combustion engine 2 is coupled to the second torque input 8 of the torque superimposition device 4, each by means of shaft connections (not shown).The first torque input 12 is connected to the first transmission device and the second torque input 8 is connected to the second transmission device, this connection here merely consisting in a continuation of the respective input shafts 8 and 12 and a mounting, as is familiar to the person skilled in the art, of the respective fixed gears of the spur gear set pairs 5a and 5b, 6a and 6b, which form the respective transmission stages 5, 6, 7; 13, 14, on the input shafts 8 and 12.

[0032] On the output side, the idler gears 5b, 6b, 7b, 13b, 14b of the gear ratios 5, 6, 7; 13, 14 are arranged on the output shaft 16a. To create a rotationally fixed connection between the idler gears 5b, 6b, 7b, 13b, 14b and the output shaft 16a, Fig. Switching claws 9, 10, and 15 are arranged in the schematic diagram shown in Figure 1. The operating principle and alternative embodiments of such switching claws are known to those skilled in the art.

[0033] The output shaft 16a, together with the output spur gear 16b mounted on the output shaft 16a in a rotationally fixed manner, forms the torque output of the torque superposition device 4.

[0034] In the vehicle arrangement shown here, the output spur gear 16b is in engagement with an output differential 17, which in turn is operatively connected to the driven wheels 18 and 19 via output shafts in an arrangement known to those skilled in the art.

[0035] The internal combustion engine 2 can be coupled to the output shaft 16a by the second transmission device, designed as a "combustion engine sub-transmission," which is formed by the three gear stages 5, 6, 7. Each of the gear stages 5, 6, 7 has a gear 5a, 6a, 7a that is rotationally fixedly connected to the crankshaft of the internal combustion engine 2. The gears 5a, 6a, 7a mesh with associated gears 5b, 6b, 7b, each of which is rotatably mounted on the output shaft 16a.

[0036] A double shifting element 9 and a single shifting element 10 are provided here to shift the "three gears" of the internal combustion engine sub-transmission. A synchronization device (not shown in detail here) can be assigned to each of the shifting elements for each of the gears. Via the internal combustion engine sub-transmission, torque or drive power can be transmitted from the crankshaft 8 of the internal combustion engine 2 to the output shaft 16a of the torque superimposition device 4 and from there via the output spur gear 16b to the output differential 17.

[0037] The electric machine 3 is electrically connected to an electrical energy storage device, e.g., a lithium-ion battery 11. When the electric machine 3 operates as a motor, it is supplied with electrical energy from the battery 11. When the electric machine 3 operates as a generator, the power generated by the generator is fed into the battery 11.

[0038] The electrical machine 3 has a rotor shaft which is connected via a Fig. 1 is connected to the first torque input via a flange connection (not shown). The first torque input, like the second torque input 8, is designed here as an input shaft 12. The rotor shaft 12 can be coupled to the output shaft 16a via two switchable gear stages 13, 14, which essentially form “a partial transmission of the electric machine 3”. The gear stages 13, 14 each have a gear 13a or 14a arranged in a rotationally fixed manner on the input shaft 12, which each meshes with an associated gear 13b, 14b which is rotatably arranged on the output shaft 16a. A double switching element 15 is assigned to the two rotatably arranged gears 13b, 14b, via which double switching element 15 the electric machine 3 can be rotationally coupled to the output shaft 16a either via the gear stage 13 or via the gear stage 14.

[0039] The gear 16b, which is arranged on the output shaft 16a in a rotationally fixed manner, forms the “torque output” of the torque superposition device 4. The gear 16b meshes with a drive wheel, not shown in detail here, of a differential gear 17, which feeds the drive power generated by the internal combustion engine 2 and the electric machine 3 into drive wheels 18, 19 of a vehicle, not shown in detail here.

[0040] The gear ratios of the gear stages 5, 6, 7, which are designed as gear pairs and thus the switchable gears of the combustion engine, are selected here so that the first gear (= gear stage 5) can be used as a starting gear or as a hill gear at low speeds up to about 40 km / h, the second gear (= gear stage 6) is designed as a driving gear under the condition that a stable top speed can be achieved, and the third gear (= gear stage 7) is designed as an efficiency gear with a longer design than the driving gear.

[0041] The gear ratios of the gear stages 13, 14, which are designed as gear pairs and thus the switchable gears of the electric motor, are selected here so that the first gear (= gear stage 14) is designed as a dynamic gear with a short gear ratio and the second gear (= gear stage 13) is designed as a gear suitable for maximum speed.

[0042] In terms of performance, the drive units are designed to achieve a stable top speed using the rated power of the combustion engine. For typical small vehicles with an unladen weight of approximately 1,200 kg and a top speed of more than 160 km / h, this means a minimum combustion engine power of approximately 50 kW.

[0043] If the rated power of the combustion engine is selected to be low (in the case described here at approximately 50 kW), the continuous power of the electric motor should be in the range of the rated power of the combustion engine.

[0044] If, however, the rated power of the combustion engine is higher, it is sufficient to select the peak power of the electric motor approximately equal to the rated power of the combustion engine. The peak power of the electric motor is the power that an electric motor can deliver for a short period of time, usually for about 10 seconds. This peak power is typically about twice the continuous power of the electric motor.

[0045] With the Fig. 1, it is fundamentally possible to generate the propulsion torque required for propelling the vehicle purely by means of the internal combustion engine or purely by means of the electric motor or in mixed operation, ie both drive units are engaged.

[0046] In addition, the electric motor can be operated as a motor or generator, so that in addition to recovering braking energy, electrical energy can also be generated by increasing the load point of the combustion engine.

[0047] An advantage of the invention compared to solutions for hybrid drives known from the prior art is that the units can be switched independently of each other, i.e. the unit operating point of the combustion engine and the electric motor can be set independently of each other.

[0048] For example, it is possible to operate the combustion engine in its efficiency mode while simultaneously operating the electric motor in its dynamic mode. This ensures that the "base load" required to propel the vehicle is generated efficiently by the combustion engine, while simultaneously ensuring high dynamic performance via the electric motor thanks to the torque characteristics typical of electric motors and the short dynamic gear ratio.

[0049] Furthermore, thanks to the switchable second gear ratio 13, the electric motor can remain integrated into the drivetrain even up to the vehicle's maximum speed, allowing propulsion torque to be generated by the electric motor even at very high speeds, or braking or deceleration energy to be recuperated during deceleration. With conventional single-speed solutions, either the vehicle's top speed must be limited or the electric motor must be decoupled.

[0050] The electric motor can also be operated with optimized efficiency thanks to the two gear ratios.

[0051] Fig. 2 shows a variant of the hybrid concept of the Fig. 1. An intermediate shaft 20 is also provided here, which makes it possible to use the gear ratio 14 of the electric machine 3 to represent a short-geared starting gear of the combustion engine 2. The gear sets of the gear ratios arranged on the output shaft 16a are arranged as in Fig. 1 are designed as switchable idler gears. This configuration also serves to charge the battery (not shown) via the electric motor 3 when stationary.

[0052] Alternatively to the Fig. 2, the electric machine could also be coupled to the intermediate shaft 20.

[0053] In the Fig. In the embodiment shown in Figure 2, the crankshaft 8 of the internal combustion engine 2 can also be coupled via a clutch 21 to a second electric machine 22, which drives an auxiliary unit 23, which can be, for example, an air conditioning compressor.

[0054] In Fig. Figure 3 shows a further embodiment of the invention in a three-shaft arrangement, with the three shafts arranged axially parallel to each other. The structure and mode of operation correspond to the embodiments described above, with the first gear stage VM1 of the internal combustion engine, designed as a starting and downhill gear, being implemented here by shared use of the electric motor sub-transmission via EM1, thus via gears 5a, 5b, 5c, and 14.

[0055] Additionally, a fourth gear VM1 / 2 can be represented here, arranged between VM1 and VM2 on the transmission side, in which the electric motor sub-transmission is shared via EM2, thus via gears 5a, 5b, 5c, and 13. In these cases with gear selection VM1 or VM1 / 2, however, the electric motor can no longer be switched independently of the combustion engine; instead, gear selection EM1 is also required for gear selection VM1, and gear selection EM2 is required for gear selection VM1 / 2.

[0056] Also in the Fig. In the embodiment of the invention shown in Figure 3, stationary charging is possible, ie charging of the electrical energy storage device by means of generator operation of the electric motor driven by the combustion engine when the vehicle is stationary.

[0057] In addition, Fig. 3 shows a starting clutch AK arranged between the combustion engine and the torque input of the torque superposition device, which serves to enable combustion engine starting via VM1.

[0058] Fig. 4 shows an embodiment which is essentially the same as the Fig. 2, with two additional clutches K0 and K1 being provided. Both clutches K0 and K1 do not need to be provided. Only one of the two clutches K0 or K1 can be provided. The intermediate shaft 20 is also not necessarily required.

[0059] The K1 clutch can be used to "decouple" the combustion engine 2, e.g., in purely electric mode. The K1 clutch can be configured as a starting clutch, which enables starting using only the combustion engine.

[0060] Via clutch K0, torque (a "support torque") can be transferred from torque input 8 to torque input 12, or vice versa. This enables shifting without interruption of traction.

[0061] In purely electric motor operation, i.e. when the vehicle is driven exclusively by the electric machine 3, the clutch K1 is open. The combustion engine 2 is therefore decoupled. Torque is transmitted from the electric machine 3 via one of the two gear stages 13 or 14 to the output shaft 16a. The output shaft 16a drives the differential gear 17. In purely electric driving mode, it is possible to switch from the gear stage currently transmitting torque (e.g. from gear stage 13) to the other gear stage (e.g. gear stage 14). For this purpose, the gears of the relevant gear stages 13, 14 arranged on the “torque input 12” or on the output shaft 16a can, for example, be designed as switchable gears, i.e. they can be arranged rotatably on the relevant shaft and rotationally coupled to the relevant shaft by actuating associated switching devices (e.g. sliding sleeves).

[0062] During such a shifting operation, clutch K0 can be switched to a "slip state," i.e., a state in which it slips (slightly) and transmits a certain "support torque." At the same time, the shiftable gear of one gear stage (e.g., gear stage 13) can be disengaged by actuating the associated shifting device, and the shiftable gear of the other gear stage (e.g., gear stage 14) can be switched to a torque-transmitting state. At the same time, torque can be transmitted to the output shaft 16a via the slipping clutch K0 and one of the two gear stages 5 or 6, enabling shifting without an interruption in traction.

[0063] Shifting without interruption of traction is also possible in “mixed operation”, ie when the vehicle is driven simultaneously by the combustion engine 2 and the electric machine 3.

[0064] Torque is transmitted, for example, from the combustion engine 2 to the output shaft 16a via one of the two gear stages 5 or 6. If a switch is to be made from the currently active gear stage (e.g., gear stage 5) to another gear stage (e.g., gear stage 6), the clutch K0 can be switched to a slip state during the switching process, and torque can be transmitted from the unit of the switching sub-transmission (e.g., combustion engine 2) to the output shaft 16a via one of the remaining gear stages (e.g., gear stages 13 or 14) of the non-switching sub-transmission. Thus, in addition to the supporting effect of the wheel torque by the unit of the non-shifting partial transmission (e.g. the electric machine 3 via partial transmissions 13, 14), further torque from the unit (e.g. combustion engine 2) of the shifting partial transmission (e.g. partial transmissions 5, 6) can be used to maintain the tractive force level during a gear change.As a result, the maximum tractive force is no longer limited to the potential of the supporting unit (e.g., electric motor 3) of the non-shifting sub-transmission. The same applies to a shift of sub-transmissions 13, 14.

[0065] In the Fig. In the embodiment shown in Figure 4, a relatively “simple”, cost-effective combustion engine can be used without having to accept any loss of function or performance (e.g. combustion engine without turbocharger system, without variable valve train, etc.).

Claims

[1] Hybrid drive (1) for motor vehicles for passenger cars, with - an internal combustion engine (2), - an electrical machine (3), and - a torque superimposition device (4) by means of which a torque supplied by the internal combustion engine (2) can be superimposed with a torque supplied by the electric machine (3), wherein the torque superimposition device (4) has a first and a second torque input (12, 8) and a torque output (16a) as well as a first transmission device (13, 14) and a second transmission device (5, 6, 7), and the electric machine (3) can be coupled to the first torque input (12) and the internal combustion engine (2) to the second torque input (8), wherein the first torque input (12) is connected to the first transmission device (13, 14) and the second torque input (8) is connected to the second transmission device (5, 6, 7), and the transmission devices (5, 6, 7; 13, 14) are each coupled to the torque output on the output side, characterized by , that the second transmission device has exactly two alternatively selectable transmission stages (5, 6) and the first transmission device has at least two alternatively selectable transmission stages (5, 6, 7; 13, 14) and where • a clutch (K0) which can be switched into a slip state is provided, by means of which torque can be transmitted from the first torque input (12) to the second torque input (8), or vice versa, and • the clutch (K0) is arranged between the two torque inputs (8, 12), whereby the two torque inputs (8, 12) can be brought to the same speed by closing the clutch • and the peak power of the electric motor is at least 30% of the rated power of the combustion engine. [2] Hybrid drive according to claim 1, characterized bythat the gear ratios of the second gear ratio device are designed in such a way that one gear ratio is designed as a maximum speed gear and another gear ratio is designed as an efficiency gear. [3] Hybrid drive according to claim 1 or 2, characterized by that the first transmission device has exactly two alternatively selectable transmission stages (13, 14), wherein the longer transmission stage is designed as the highest speed gear of the vehicle. [4] Hybrid drive (1) according to one of claims 1 to 3, characterized by that the hybrid drive (1) has exactly one electric, vehicle propulsion-generating machine (3). [5] Hybrid drive (1) according to one of claims 1 to 4, characterized bythat the torque output of the torque superposition device is designed as an output shaft with an output gear stage (16b), wherein the output gear stage (16b) is directly connected to a differential of the driven vehicle axle of the motor vehicle. [6] Hybrid drive (1) according to one of the preceding claims, characterized by that the torque superposition device (4) comprises three shafts, wherein the first shaft is connected to the first torque input, the second shaft to the second torque input and the third shaft to the torque output and the transmission stages of the transmission devices are designed as spur gear sets which are arranged on the respective shafts. [7] Hybrid drive (1) according to one of claims 1 to 6, characterized by that switching elements (9, 10, 15) are provided for switching the gear ratios (5, 7; 13, 14). [8] Hybrid drive (1) according to claim 7, wherein each gear ratio stage (5-7; 13, 14) is assigned a synchronizing device. [9] Hybrid drive (1) according to one of the preceding claims, characterized by that the rated power of the combustion engine is equal to or greater than the power requirement at the maximum speed of the motor vehicle and that the peak power of the electric motor is greater than 80% of the rated power of the combustion engine. [10] Hybrid drive (1) according to claim 9, characterized by that the rated power of the combustion engine is a maximum of 1.5 times the power requirement at the maximum speed of the motor vehicle and that the continuous power of the electric motor is greater than 80% of the rated power of the combustion engine. [11] Hybrid drive (1) according to one of the preceding claims, characterized bythat a clutch (K1) is arranged between a crankshaft of the internal combustion engine and the second torque input of the torque superposition device.

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