Drive unit, motor vehicle and method for operating a motor vehicle

Abstract

Drive unit (12) for a motor vehicle (10), comprising a motor vehicle drive motor (14) arranged in the region of a first motor vehicle axle (20), and a gear transmission (26) coupled to the motor vehicle drive motor (14) via a motor output shaft (24) and arranged in the region of a second motor vehicle axle (28), wherein the motor vehicle drive motor (14) can drive wheels (34a, 34b) of the second motor vehicle axle (28), wherein the drive unit (12) additionally comprises an electric drive device (39), wherein the electric drive device (39) comprises a third electric drive motor (38), wherein the third electric drive motor (38) is arranged in the region of the second motor vehicle axle (28) and can be selectively coupled to the wheels (34a, 34b) of the second motor vehicle axle (28), and the third electric drive motor (38) is coupled to the wheels (34a, 34b) of the second motor vehicle axle (28) via a summing gear unit.34b) the second motor vehicle axle (28) is couplingable and wherein the sum gear unit is a planetary gear unit.,

Description

[0001] The invention relates to a drive unit for a motor vehicle, comprising a motor vehicle drive motor arranged in the area of ​​a first motor vehicle axle, preferably a motor vehicle front axle, and a gearshift transmission coupled to the motor vehicle drive motor via a motor output shaft, which is arranged in the area of ​​a second motor vehicle axle, preferably a motor vehicle rear axle, wherein wheels of the second motor vehicle axle can be driven by means of the motor vehicle drive motor.

[0002] The invention also relates to a motor vehicle with such a drive unit.

[0003] In addition, the invention relates to a method for operating a motor vehicle with a drive unit of the type mentioned at the outset.

[0004] Such drive architectures are known as transaxles. They allow for a particularly even weight distribution across both axles of a vehicle. Therefore, this drive architecture is primarily used in sports cars.

[0005] At the same time, increasing demands regarding fuel consumption and emissions particularly affect sports cars, since sporty driving performance has so far generally been associated with comparatively high fuel consumption and relatively large emission values.

[0006] WO 2009 / 019 580 A2 shows a vehicle with all-wheel drive and hybrid drive, the drive design being a transaxle.

[0007] WO 2009 / 021 574 A1 discloses a drive train for a motor vehicle, wherein the motor vehicle has a first and a second axle. Furthermore, a drive unit is arranged in the region of the first axle and an electric machine in the region of the second axle.

[0008] In DE 10 2006 059 901 A1 a motor vehicle with a rear or front engine and a transmission is shown, wherein the engine has a crankshaft running in the longitudinal direction of the motor vehicle, and wherein the engine and the transmission are arranged separately from each other in the rear, in the middle of the vehicle or in the front area of ​​the vehicle in a transaxle design.

[0009] DE 103 19 108 A1 discloses an all-wheel drive vehicle with a hybrid drive comprising an internal combustion engine, a first drive train to a first driven axle, a second drive train to a second driven axle, an electric machine in the second drive train, and a first clutch before and a second clutch after the electric machine.

[0010] In WO 2009 / 006 967 A1 a hybrid vehicle with at least one electric motor is shown, whereby the electric motor is intended as at least an additional drive to an internal combustion engine during a drive phase.

[0011] The object of the invention is therefore to create a drive architecture that enables both sporty driving performance and low fuel consumption and emissions. Furthermore, the drive architecture should occupy the smallest possible installation space so that it can be flexibly used for different vehicle concepts or vehicle bodies.

[0012] The problem is solved by a drive unit of the type mentioned above, which additionally includes an electric drive system. This electric drive system comprises a third electric drive motor, arranged in the area of ​​the second vehicle axle and selectively coupled to the wheels of the second vehicle axle. The third electric drive motor can be coupled to the wheels of the second vehicle axle via a summing gear unit, which is a planetary gear set. This is therefore a hybrid drive unit with a transaxle architecture. The drive unit can be designed as a series or parallel hybrid. The electric drive system reduces the fuel consumption of a vehicle equipped with it while maintaining the same driving performance. The same applies to emissions.Simultaneously, an even weight distribution across both axles is achieved, contributing to both a sporty and a balanced, comfortable driving experience. In particular, this results in excellent traction and a high moment of inertia around the vehicle's vertical axis. This allows the transaxle shaft, which connects the vehicle's drive motor to the transmission, to be made lighter and / or smaller while maintaining performance. This is because the torque generated by the electric drive unit does not need to be transmitted via the transaxle shaft.

[0013] The second axle of the vehicle can therefore be driven either by the vehicle's main engine, the third electric motor, or by both. This allows for a hybrid drive system for the second axle. Consequently, the fuel consumption and emission advantages known from hybrid drives can be achieved.

[0014] Such a coupling is suitable for transmitting high torques while requiring relatively little space. Additionally, switching between a drive via the vehicle's traction motor, the third electric drive motor, and both can be done easily and reliably.

[0015] According to one embodiment, the electric drive system comprises a first electric drive motor and a second electric drive motor, the drive motors being arranged in the area of ​​the first vehicle axle and each being selectively coupled to a wheel of the first vehicle axle. Thus, all wheels can be driven, creating a hybrid all-wheel drive system. Since the wheels of the first vehicle axle are driven exclusively by electric drive motors, an axle differential and / or a differential lock can be omitted. The same functions can be achieved by controlling the electric drive motors. The yaw angle of a vehicle can also be influenced via torque vectoring. Such a drive system has a compact design.In particular, compared to a classic transaxle design, it does not restrict the space around the second axle. This preserves the available trunk space. More generally, due to its compact size, a single drive unit can be used in numerous different vehicle concepts, such as roadsters, sedans, and compact vans. It is therefore universally applicable.

[0016] The first and second electric drive motors can be wheel hub motors. Such motors are particularly space-saving, making the associated drive unit especially versatile.

[0017] Preferably, the vehicle drive motor is arranged between the first and second electric drive motors. Preferably, it is located centrally between the first and second electric drive motors. The vehicle drive motor, along with the first and second electric drive motors, thus forms a compact unit in the area of ​​the first vehicle axle.

[0018] The vehicle's drive motor can also be coupled to the wheels of the second vehicle axle via the sumr gear unit.

[0019] Preferably, the third electric drive motor is located geometrically and / or functionally between the transmission and an axle drive of the second vehicle axle, preferably wherein the transmission, the axle drive, and the third electric drive motor are arranged in a common housing. Such an arrangement is particularly compact. Due to the functional arrangement of the third electric drive motor upstream of the axle drive, both wheels of the second vehicle axle can be driven by only one electric drive motor.

[0020] The drive unit can include a starting clutch, by means of which the vehicle's drive motor and the transmission can be selectively connected in a torque-conducting manner. The starting clutch is located in the area of ​​the second vehicle axle. Particularly when a first and a second drive motor are present, this shifts additional weight to the second vehicle axle, resulting in a particularly even weight distribution. The starting clutch can also be used to completely decouple the vehicle's drive motor. The drive unit is then operated purely electrically. Due to the proximity of the starting clutch to the transmission, the latter can be easily synchronized.

[0021] Advantageously, the starting clutch and the gearshift are housed together in a single casing. This allows for a particularly space-saving design of the drive unit. Furthermore, it is easy to install and cost-effective to manufacture.

[0022] The motor for a motor vehicle can be an internal combustion engine or a fuel cell.

[0023] The problem is further solved by a motor vehicle of the type mentioned above with a drive unit according to the invention. Such a motor vehicle has a particularly even weight distribution between the vehicle axles. This results in high driving dynamics and overall balanced handling. In addition, such a motor vehicle has low fuel consumption and emission values. Since the drive unit occupies only a small installation space, the vehicle can be equipped with a wide variety of vehicle bodies.

[0024] Furthermore, the problem is solved by a method for operating a motor vehicle with a drive unit according to the invention, wherein the drive unit is switched between the following drive modes: a) Driving wheels of a first motor vehicle axle, preferably a vehicle front axle, by means of a first electric drive motor assigned to a first wheel of the first motor vehicle axle and a second electric drive motor assigned to a second wheel of the first motor vehicle axle, as well as driving wheels of a second motor vehicle axle by means of a third electric drive motor in an electric all-wheel drive mode, b) Driving the wheels of the second motor vehicle axle exclusively by means of the motor vehicle drive motor in a first second-axle mode, c) Driving the wheels of the second vehicle axle exclusively by means of the third electric drive motor in a second two-axle mode, d) Driving the wheels of the second motor vehicle axle both by means of the motor vehicle drive motor and by means of the third electric drive motor in a third second-axle mode, e) Driving the wheels of the first motor vehicle axle by means of the first and second electric drive motors in a first-axle mode, and f) Driving the wheels of the first motor vehicle axle by means of the first and the second electric drive motor and the wheels of the second motor vehicle axle by means of the motor vehicle drive motor, wherein the wheels of the second motor vehicle axle are preferably additionally driven by the third electric drive motor, in a hybrid all-wheel drive mode.

[0025] The third two-axle mode can also be called boost mode. In this mode, the power outputs of the vehicle's main engine and the third electric drive motor are combined. This allows, among other things, for dynamic acceleration. The drive modes are selected based on vehicle parameters. These parameters can include vehicle speed, the state of charge of an electric energy storage device, the accelerator or gas pedal position, and / or the setting of a driving experience switch. If the vehicle's electric energy storage device is depleted, only the first two-axle mode remains available. The vehicle can therefore always be operated in a mode that ideally combines fuel consumption, emissions, and driving dynamics requirements.In particular, the all-wheel drive modes enable driving with exceptional traction, which is especially advantageous on a smooth and / or wet road surface.

[0026] According to one variant, in a recuperation mode, the first, second, and / or third electric drive motor(s) act as generators and charge an electrical energy storage device. This ensures efficient use of electrical energy, contributing to low fuel consumption and emissions.

[0027] The invention is explained below with reference to an exemplary embodiment shown in the accompanying drawing. It shows: - Fig. 1 a motor vehicle according to the invention, which can be operated by means of a method according to the invention and comprises a drive unit according to the invention.

[0028] A motor vehicle 10 is equipped with a drive unit 12.

[0029] The drive unit 12 comprises a motor vehicle drive motor 14, a first electric drive motor 16 and a second electric drive motor 18.

[0030] These are arranged in the area of ​​a first motor vehicle axle 20, which in the illustrated embodiment is a front axle.

[0031] The motor vehicle drive motor 14 is located centrally between the first electric drive motor 16 and the second electric drive motor 18.

[0032] The first electric drive motor 16 can be optionally coupled to a wheel 22a of the first motor vehicle axle 20 and the second electric drive motor 18 can be coupled to a wheel 22b.

[0033] Both electric drive motors 16, 18 can also be wheel hub motors, unlike in the illustrated embodiment.

[0034] A gearshift transmission 26 is coupled to the vehicle drive motor 14 via a motor output shaft 24.

[0035] The gearshift transmission 26 is located in the area of ​​a second vehicle axle 28, which in the illustrated embodiment is a rear axle.

[0036] The wheels 34a, 34b of the second vehicle axle 28 can be driven by the vehicle drive motor 14 via the gear transmission 26, which can be optionally connected to the vehicle drive motor 14 in a torque-conducting manner by means of a starting clutch 30, and an axle transmission 32.

[0037] The starting clutch 30 and the axle drive 32 are also located in the area of ​​the second vehicle axle 28.

[0038] The starting clutch 30 is housed together with the gearshift transmission 26 in a common housing 36.

[0039] In addition, a third electric drive motor 38 is provided in the area of ​​the second motor vehicle axle 28, which can optionally be coupled with the wheels 34a, 34b.

[0040] The third electric drive motor 38 and the motor vehicle drive motor 14 can be coupled to the wheels 34a, 34b via a summation gear unit not shown in detail, which is designed, for example, as a planetary gear.

[0041] The third electric drive motor 38 is located geometrically and functionally between the gearshift transmission 26 and the axle transmission 32.

[0042] The gearshift 26, the axle drive 32, and the third electric drive motor 38 can be housed in a common casing. For the sake of clarity, this is shown in Fig. 1 not shown.

[0043] The first electric drive motor 16, the second electric drive motor 18 and the third electric drive motor 38 form an electric drive unit 39.

[0044] The motor vehicle 10 is also equipped with an energy storage system 40. This includes both an electrical energy storage system, which supplies the electric drive unit 39, and a fuel storage system for the motor vehicle's drive engine 14.

[0045] The motor for the motor vehicle 14 can be an internal combustion engine or a fuel cell.

[0046] The motor vehicle 10 with the drive unit 12 can be operated in different drive modes, between which switching occurs depending on vehicle parameters such as vehicle speed, the fill level of the energy storage 40, or the accelerator or gas pedal position. The drive modes can also be switched depending on the position of a driving experience switch.

[0047] For example, an energy-saving mode, a comfort mode or a sport mode can be selected via the driving experience switch.

[0048] In an electric all-wheel-drive mode, the wheels 22a, 22b of the first vehicle axle 20 are driven by the first electric drive motor 16, which is assigned to wheel 20a, and the second electric drive motor 18, which is assigned to wheel 20b. Furthermore, the wheels 34a, 34b of the second vehicle axle 28 are driven by the third electric drive motor 38.

[0049] Alternatively, a hybrid all-wheel-drive mode is available, in which wheels 22a and 22b are driven by the first electric drive motor 16 and the second electric drive motor 18, respectively. Wheels 34a and 34b are driven by the vehicle drive motor 14.

[0050] Optionally, the wheels 34a and 34b can also be driven by the third electric drive motor 38. In this case, this is also referred to as a boost mode, since the power of the third electric drive motor 38 is combined with the power of the vehicle drive motor 14.

[0051] In addition, two-axle modes are available in which only the wheels 34a, 34b of the second vehicle axle 28 are driven.

[0052] In a first two-axle mode, wheels 34a, 34b are operated exclusively by means of the vehicle drive motor 14. This mode is selected when the energy storage devices for the first, second and third electric drive motors 16, 18, 38 are depleted.

[0053] In a second two-axle mode, wheels 34a and 34b are driven exclusively by means of the third electric drive motor 38. In the illustrated embodiment, this results in a purely electric rear-wheel drive.

[0054] The wheels 34a and 34b can also be driven in a third two-axle mode by either the vehicle drive motor 14 or the third electric drive motor 38. This operating mode is a boost mode, which allows for particularly high acceleration.

[0055] Furthermore, a first-axle mode is available in which wheels 22a and 22b are driven exclusively by the first electric drive motor 16 and the second electric drive motor 18. This is therefore a purely electric front-wheel drive.

[0056] Furthermore, in a recuperation mode, the first electric drive motor 16, the second electric drive motor 18, and / or the third electric drive motor 38 can act as generators. In this operating mode, an electrical energy storage device included in the energy storage unit 40 can be charged.

Claims

[1] Drive unit (12) for a motor vehicle (10), comprising a motor vehicle drive motor (14) arranged in the region of a first motor vehicle axle (20), and a gear transmission (26) coupled to the motor vehicle drive motor (14) via a motor output shaft (24) and arranged in the region of a second motor vehicle axle (28), wherein the motor vehicle drive motor (14) can drive wheels (34a, 34b) of the second motor vehicle axle (28), wherein the drive unit (12) additionally comprises an electric drive device (39), wherein the electric drive device (39) comprises a third electric drive motor (38), wherein the third electric drive motor (38) is arranged in the region of the second motor vehicle axle (28) and can be selectively coupled to the wheels (34a, 34b) of the second motor vehicle axle (28), and the third electric drive motor (38) is coupled to the wheels (34a, 34b) of the second motor vehicle axle (28) via a summing gear unit.34b) the second motor vehicle axle (28) is couplingable and wherein the sum gear unit is a planetary gear unit., [2] Drive unit (12) according to claim 1, characterized by , that the electric drive device (39) comprises a first electric drive motor (16) and a second electric drive motor (18), wherein the drive motors (16, 18) are arranged in the area of ​​the first motor vehicle axle (20) and can each be selectively coupled to a wheel (22a, 22b) of the first motor vehicle axle (20). [3] Drive unit (12) according to claim 2, characterized by , that the first electric drive motor (16) and the second electric drive motor (18) are wheel hub motors. [4] Drive unit (12) according to claim 2 or 3, characterized by , that the motor vehicle drive motor (14) is arranged between the first electric drive motor (16) and the second electric drive motor (18). [5] Drive unit (12) according to any one of the preceding claims, characterized by , that the motor vehicle drive motor (14) can also be coupled to the wheels (34a, 34b) of the second axle of the motor vehicle (28) via the sum gear unit. [6] Drive unit (12) according to any one of the preceding claims, characterized by , that the third electric drive motor (38) is located geometrically and / or functionally between the gearshift transmission (26) and an axle transmission (32) of the second vehicle axle (28). [7] Drive unit (12) according to any one of the preceding claims, characterized by , that the gear shifting transmission (26), the axle transmission (32) and the third electric drive motor (38) are arranged in a common housing. [8] Drive unit (12) according to any one of the preceding claims, characterized by, that it comprises a starting clutch (30) by means of which the motor vehicle drive motor (14) and the gear transmission (26) can be selectively connected in a torque-conducting manner, wherein the starting clutch (30) is arranged in the area of ​​the second axle of the motor vehicle (28). [9] Drive unit (12) according to claim 8, characterized by , that the starting clutch (30) is arranged together with the gearshift transmission (26) in a common housing (36). [10] Drive unit (12) according to any one of the preceding claims, characterized by , that the motor vehicle propulsion engine (14) is an internal combustion engine or a fuel cell. [11] Motor vehicle (10) with a drive unit (12) according to one of the preceding claims. [12] Method for operating a motor vehicle (10) with a drive unit (12) according to any one of claims 1 to 10, characterized by , that the drive unit (12) is switched between the following drive modes: a) Driving wheels (22a, 22b) of a first motor vehicle axle (20) by means of a first electric drive motor (16) assigned to a first wheel (22a) of the first motor vehicle axle (20), and a second electric drive motor (18) assigned to a second wheel (22b) of the first motor vehicle axle (20), as well as driving wheels (34a, 34b) of a second motor vehicle axle (28) by means of a third electric drive motor (38) in an electric all-wheel drive mode, b) Driving the wheels (34a, 34b) of the second motor vehicle axle (28) exclusively by means of the motor vehicle drive motor (14) in a first second-axle mode, c) Driving the wheels (34a, 34b) of the second motor vehicle axle (28) exclusively by means of the third electric drive motor (38) in a second two-axle mode, d) Driving the wheels (34a, 34b) of the second motor vehicle axle (28) both by means of the motor vehicle drive motor (14) and by means of the third electric drive motor (38) in a third second-axle mode, e) Driving the wheels (22a, 22b) of the first motor vehicle axle (20) by means of the first electric drive motor (16) and the second electric drive motor (18) in a first-axle mode, and f) Driving the wheels (22a, 22b) of the first motor vehicle axle (20) by means of the first electric drive motor (16) and the second electric drive motor (18) and the wheels (34a, 34b) of the second motor vehicle axle (28) by means of the motor vehicle drive motor (14). [13] Method according to claim 12 characterized by, that in a recuperation mode the first electric drive motor (16), the second electric drive motor (18) and / or the third electric drive motor (38) acts as a generator or acts as generators and charges an electrical energy storage device.

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