Electric motor gearbox unit for a drive train

Abstract

Electric motor transmission unit (1) for a drive train (22) of a motor vehicle with an internal combustion engine (16), with a first planetary gear set (8a), comprising an input shaft (3) to which the internal combustion engine (16) can be coupled, with a second planetary gear set (8b), comprising an output shaft (4) which can be coupled to drive wheels (18) of the motor vehicle, wherein the first planetary gear set (8a) and the second planetary gear set (8b) each have planetary gears (9a, b; 10a, b) which are arranged on at least two common planetary shafts (13a, b) in a rotationally fixed manner relative to one another, and wherein a planetary carrier (15), which is mounted on the input shaft (3) and the output shaft (4) for rotation about a common axis (19), is coupled or can be coupled to an electric machine (17), wherein the electric machine (17) is arranged radially outside the planetary carrier (15), and wherein the rotor (7) is connected to the planetary carrier (15) in a rotationally fixed manner and the stator (6) is coupled to a housing (2), characterized by that a differential lock (20) is provided between the input shaft (3) and the output shaft (4).

Description

[0001] The invention relates to an electric motor transmission unit for a drive train. The drive train can be the drive train of a motor vehicle with an internal combustion engine, in particular a heavy-duty vehicle (heavy-duty truck), such as a bus, garbage truck, agricultural vehicle, or construction vehicle (off-road).

[0002] It is known to install a starting module with a hydrodynamic clutch in the drivetrain of such vehicles between the combustion engine and the transmission. Such a starting module is known from DE 10 2017 128 362 A1, where the module can be used as a clutch or retarder.

[0003] A drive unit with a hybrid transmission is disclosed in DE10 2018 125 082 A1. The internal combustion engine and electric motor are connected to a common output shaft via a planetary gear.

[0004] The advantage of such a drive train is that the electric motor can be used as a drive, drive assistance or as a retarder or generator.

[0005] DE 10 2018 001 471 B3 discloses a concept in which the electric motor can be coupled to the planetary gear set via a clutch.

[0006] Another transmission comprising two drive units and two planetary gears is known from DE 10 2015 006 084 A1. In this system, the second drive unit, e.g., an electric motor, is coupled to the planet carrier of both planetary gear sets.

[0007] DE 103 09 619 A1 discloses a planetary gear differential device with two planetary gear sets whose planetary gears are fixed to each other and are rotatably mounted on a common planetary carrier.

[0008] DE 101 33 919 A1 discloses another planetary gear unit with an input shaft and an output shaft, with a second output shaft being provided that can be coupled to the planetary carrier via two rotors of an electric drive that are independent of the gear housing. Furthermore, a coupling between the input shaft and the planetary carrier is proposed to lock the output shafts against each other. In the locked state, the electric drive is ineffective.

[0009] The following functions are useful and already implemented individually in modern hybrid drives for motor vehicles: - electric start, - braking or recuperation, - Starting the combustion engine - Boosting the combustion engine

[0010] To implement these functions, many concepts are known that use different components: - multi-disk or dry clutch (detachable clutch), - Disc brake and retarder, - Starter, e.g. DC motor 24V DC, with battery - various transmission concepts

[0011] A disadvantage of the current state of the art is that the aforementioned functions or modes are often implemented in isolation and only partially. Synergy effects are largely unused.

[0012] The object of the invention is to propose an improved electric motor transmission unit which enables improved vehicle operation.

[0013] The object is achieved according to the invention by an embodiment according to the independent claim. Further advantageous embodiments of the present invention can be found in the subclaims.

[0014] An electric motor transmission unit for a drive train of a motor vehicle with an internal combustion engine is proposed, comprising a first planetary gear set, comprising an input shaft to which the internal combustion engine can be coupled, and a second planetary gear set, comprising an output shaft, which can be coupled to drive wheels of the motor vehicle. The first planetary gear set and the second planetary gear set each have planetary gears that are arranged on at least two common planetary shafts in a rotationally fixed manner. Furthermore, the planetary carrier is coupled or can be coupled to an electric machine.

[0015] According to the invention, the planetary carrier is mounted on the input shaft and the output shaft so that it can rotate about a common axis. This enables operating modes that are not feasible with known solutions.

[0016] Furthermore, it is advantageous to provide a differential lock between the input and output shafts, which allows the planetary gear sets to be locked. The differential lock can also be understood as a mechanical through-connection or lock-up function. Various designs are possible. The differential lock can be a clutch or brake between the planetary carrier and the input or output shaft.

[0017] Furthermore, the differential lock can be a clutch or brake between the input shaft and the output shaft. Alternatively, the differential lock can be a clutch or brake between the planetary carrier and at least one of the planetary shafts. Alternatively, the differential lock can also be a clutch or brake between the input shaft and the housing.

[0018] In a preferred embodiment, the electric machine is arranged radially outside the planetary carrier, with the rotor being rotationally fixedly connected to the planetary carrier and the stator coupled to a housing, or the torque is supported relative to the housing. This allows for a small design in the axial direction.

[0019] Furthermore, the planetary gear sets can have different gear ratios, so the functionality of the electric motor transmission unit can be easily adapted to specific vehicle requirements.

[0020] In one embodiment, the housing may be an intermediate housing having two coupling levels so that it can be easily inserted into a drive train.

[0021] The electric motor can be a torque motor with high torque in the starting range combined with an extended speed range in field-weakening operation. These motors have the advantage that the aforementioned functions can be implemented more cost-effectively (lower power) with a comparatively small motor size.

[0022] In the drivetrain, the housing of the electric motor transmission unit is preferably designed as an intermediate housing, installed between the housings of the combustion engine and transmission. Coupling is preferably achieved via the coupling planes.

[0023] Further advantageous embodiments of the invention are explained using exemplary embodiments with reference to the drawings.

[0024] The figures show in detail: Fig. 1 electric motor gear unit Fig. 2 Drivetrain with electric motor transmission unit

[0025] In Fig. 1 shows the electric motor transmission unit 1. The electric motor transmission unit 1 comprises a first planetary gear set 8a and a second planetary gear set 8b, both planetary gear sets being designed without a ring gear.

[0026] A planetary gear set thus consists of a sun gear 11 or 12 and a set of planet gears 9a, b or 10a, b, each of which meshes with the sun gears 11 / 12. At least two planetary axes 13a, b are mounted on the planet carrier 15, distributed around the circumference, and rotatably supported.

[0027] Depending on the desired application, the planetary gear sets 8a, b can have the same or different gear ratios, whereby the planetary gears arranged on a planetary axis 13a, b, such as 9a and 10a, are connected to one another in a rotationally fixed manner or are connected to the planetary shaft in a rotationally fixed manner.

[0028] In a drive arrangement in which the Fig. 1 is used, a first drive unit, the combustion engine 16, engages the input shaft 3, and the second drive unit, the electric motor 17, engages the planetary carrier 15. The output shaft 4 is connected directly or indirectly to a drive axle of a motor vehicle.

[0029] In order to achieve improved operational capability, the planet carrier 15 is mounted on the input shaft 3 and the output shaft 4 via the bearings 5 ​​so that it can rotate about the common axis 19.

[0030] Fig. Figure 2 shows an example of a drive train 22 for a motor vehicle. The input shaft 3 is driven by the combustion engine 16, and the output shaft is connected to the drive wheels via another transmission 21.

[0031] The electric motor transmission unit 1 is a so-called superposition drive, which comprises an electric motor that engages or is coupled to the planetary carrier 15. The preferably used electric motor can be a torque motor, which has the advantage of being able to provide high torque in the starting range and still provide power for braking and boost operation during nominal operation.

[0032] Another essential element of the electric motor transmission unit is a differential lock 20, which can be designed as a brake, locking device, or clutch. The differential lock 20 is Fig.1 is arranged between the output shaft 4 and the planet carrier 15. At this position, the differential lock 20 ensures a direct coupling of the input shaft 3 and the output shaft 4, so that relative rotation between the output shaft 4 and the planet carrier 15 can be blocked. Alternatively, this relative rotation can also be prevented by arranging the differential lock 20 between the input shaft 3 and the planet carrier 15, between the input shaft 3 and the output shaft 4, or between the planet carrier 15 and the coupled planet gears 9a, 10a.

[0033] The differential lock enables different drive or power flows and allows the two drive motors 16, 17 to be operated differently. Although the internal combustion engine 16 can only be operated in one direction of rotation, the engine control system allows different speeds and torques to be applied to the input shaft 3. To start the internal combustion engine 16, a torque would have to be applied to the input shaft.

[0034] The electric motor 17 can be used as a drive motor or as a generator, so that the planetary carrier 15 is braked or accelerated. Idle operation is also conceivable, in which the electric motor acts as a generator to provide electrical energy, for example, for attachments in the agricultural sector.

[0035] However, torques can be introduced into the electric motor transmission unit 1 not only via the drives 16, 17 but also via the output shaft 4. Thus, the generator torque and / or the drag torque of the combustion engine can be used to brake the vehicle in order to enable wear-free braking.

[0036] When the differential lock is open, the speeds of input shaft 3 and output shaft 4 can differ depending on the mode of the electric motor transmission unit 1. The size of the speed difference depends on the gear ratio selected for the two planetary gear sets 8a, b.

[0037] The electric motor transmission unit 1 according to the invention can be switched to the following modes: 1) Vehicle stationary: a) Starting the combustion engine 16: -> by fixing the output shaft (e.g. by engaging the parking brake), the electric motor 17 can be used as a starter b) Electric machine in generator function: -> with running combustion engine 16 and fixed output shaft (e.g. by parking brake) the electric motor 17 can be used as a generator 2) Starting / driving the motor vehicle a) Electric motor as superposition drive -> The electric motor adjusts the speed between input shaft 3 and output shaft 4 b) Electric motor for starting without combustion engine 16 -> the combustion engine 16 is off, so that the input shaft is stationary, the electric motor 17 drives only the output shaft 4 via planetary gear sets c) Boosting the combustion engine with active differential lock 20 -> The differential lock 20 directly couples the input and output shafts and the electric motor can be used to support the drive power. 3) Braking of the motor vehicle a) Electric motor 17 as generator - differential lock 20 open -> the speed of the output shaft is translated into high speed, so that the essential braking torque is generated via the electric motor. b) Electric motor 17 as generator - differential lock 20 closed -> the braking torque is applied by electric motor 17 and combustion engine 16 4) improved shifting of a downstream gearbox through active speed adjustment (synchronization) with the electric generator.

[0038] All of the modes briefly described can be switched particularly advantageously with an electric motor transmission unit according to the invention. The operating mode "electric machine 17 in superposition mode" offers, in addition to the modes mentioned, further intervention options during driving. Depending on the selection of the gear ratios in the planetary gear sets 8a, b, a different increase or decrease in gear ratio can be achieved during driving, or even a change in the direction of rotation of the output shaft can be achieved, so that a reverse gear in the downstream transmission 21 is unnecessary. The electric machine is used for the superposition function, through which the speed ratio between the input shaft 3, which depends on the combustion engine speed during driving, and the output shaft 4 can be changed.

[0039] This covers the general basic problems and requirements when operating vehicles. • Due to the given reduction, the “long 1st gear” will continue to be available for city buses and will also enable braking energy or recuperation and short purely electric driving, e.g. at closely spaced stops • For example, for refuse collection vehicles, fully electric operation at low speeds and frequent start / stop operation is conceivable, including brake energy recovery • For construction and agricultural machinery, there is the possibility of generating stationary electricity (400V genset), e.g. for electrical attachments such as saws and wood splitters • Heavy-duty vehicles can be started with high torque and maneuvered comfortably at low speed

[0040] The electric motor transmission unit 1 can be installed as a separate module in the drive train 22. The special design makes it possible to minimize the additional space required in the longitudinal direction of the drive train 22. Alternatively, integration into one of the adjacent housings is also conceivable.

[0041] As is generally known, a planetary gear set can also have more than the planetary gears 9a, b or 10a, b shown. Three or more planetary gears are also common. List of reference symbols 1 electric motor gear unit 2 housings 3 Input shaft 4 Output shaft 5 warehouses 6 Stator 7 Rotor 8a, b planetary gear set 9a, b planetary gear 10a, b planetary gear 11 Sun gear 12 Sun gear 13a, b Planetary waves 14a, b coupling level 15 planet carriers 16 combustion engine 17 electric machine 18 drive wheels 19 Axis 20 Differential lock 21 gearboxes 22 Drivetrain

Claims

[1] Electric motor transmission unit (1) for a drive train (22) of a motor vehicle with an internal combustion engine (16), with a first planetary gear set (8a), comprising an input shaft (3) to which the internal combustion engine (16) can be coupled, with a second planetary gear set (8b), comprising an output shaft (4) which can be coupled to drive wheels (18) of the motor vehicle, wherein the first planetary gear set (8a) and the second planetary gear set (8b) each have planetary gears (9a, b; 10a, b) which are arranged on at least two common planetary shafts (13a, b) in a rotationally fixed manner relative to one another, and wherein a planetary carrier (15), which is mounted on the input shaft (3) and the output shaft (4) for rotation about a common axis (19), is coupled or can be coupled to an electric machine (17), wherein the electric machine (17) is arranged radially outside the planetary carrier (15), and wherein the rotor (7) is connected to the planetary carrier (15) in a rotationally fixed manner and the stator (6) is coupled to a housing (2), characterized by , that a differential lock (20) is provided between the input shaft (3) and the output shaft (4). [2] Electric motor transmission unit (1) according to claim 1, characterized bythat the differential lock (20) is a clutch or brake between the planet carrier (15) and the input shaft (3) or output shaft (4). [3] Electric motor transmission unit (1) according to claim 1, characterized by that the differential lock (20) is a clutch or brake between the input shaft (3) and the output shaft (4). [4] Electric motor transmission unit (1) according to claim 1, characterized by that the differential lock (20) is a clutch or brake between the planet carrier (15) and at least one of the planet shafts (13a, b). [5] Electric motor transmission unit (1) according to claim 1, characterized by that the planetary gear sets (8a, b) have different ratios. [6] Electric motor transmission unit (1) according to claim 1, characterized by that the housing (2) is an intermediate housing with two coupling levels (14a, b). [7] Electric motor transmission unit (1) according to claim 1, characterized by that the electric machine (17) is a torque motor. [8] Drive train (22) with electric motor transmission unit (1) according to one of claims 1 to 7 characterized by that the housing (2) of the electric motor transmission unit (1) is an intermediate housing which is installed in the drive train (22) between the housings of the combustion engine (16) and the transmission (21).

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