CN111216548A

CN111216548A - Electromechanical drive device for a motor vehicle

Info

Publication number: CN111216548A
Application number: CN201911037802.9A
Authority: CN
Inventors: 克里斯蒂安·哈特曼
Original assignee: Schaeffler Technologies AG and Co KG
Current assignee: Schaeffler Technologies AG and Co KG
Priority date: 2018-11-27
Filing date: 2019-10-29
Publication date: 2020-06-02
Also published as: DE102018129933B3

Abstract

The invention relates to an electromechanical drive device for a motor vehicle, comprising: an electric motor having a stator and a rotor; a reduction gear unit, which is designed as a spur gear transmission and has a first spur gear stage with a first transmission ratio and a second spur gear stage with a second transmission ratio, the first spur gear stage having a first drive spur gear, which is arranged on the input shaft and engages into a first driven spur gear, which is arranged on the output shaft, and the second spur gear stage having a second drive spur gear, an intermediate wheel, which is arranged on the input shaft and engages into the intermediate wheel, and a second driven spur gear, which is arranged on the output shaft, a first freewheel being provided between the input shaft and the first drive spur gear, and a second freewheel being provided between the input shaft and the second drive spur gear.

Description

Electromechanical drive device for a motor vehicle

Technical Field

The invention relates to an electromechanical drive device for a motor vehicle, comprising: an electric motor; a reduction gear configured as a spur gear transmission; and an axle differential for branching the drive power guided via the reduction gear to the first and second wheel drive shafts.

Background

Such a drive device is known from DE 102015110839 a 1. The spur gear transmission is configured as a two-stage shiftable transmission in the drive device. The spur gear transmission has an input shaft and an output shaft. Two drive cylindrical gears are arranged on the input shaft. Two driven spur gears and an output gear provided for further power take-off are arranged on the output shaft. The first drive spur gear arranged on the input shaft and the driven first spur gear of the output shaft associated therewith realize a first transmission ratio. A second drive spur gear arranged on the input shaft and a second spur gear of the output shaft in conjunction therewith realize a second transmission ratio. The second drive spur gear can be coupled to the input shaft in a switchable manner via a clutch device. The two wheels mounted on the output shaft and driven in this case are coupled to the output shaft via a freewheel, so that the output shaft can pass over the respective non-last-guided driven wheel, which is driven in the same direction, however. One of the freewheel mechanisms can be connected in a switchable manner.

In a popular transmission design with spur gear stages, the gears to be shifted are shifted by means of clutches as already described above. In order to be able to engage a gear during driving, the engine is first kinematically decoupled from the input shaft of the transmission by engaging the clutch. The rotational speed of the input shaft is then synchronized to the rotational speed of the selected gear wheel taking into account the target gear ratio. Only then is a positive connection brought about between the input shaft and the wheels of the desired gear. This procedure is disadvantageous in automated transmission designs in the following cases: the internal combustion engine is disconnected from the transmission during the gear shift. Accordingly, no power flows through the transmission for the time being. So-called traction force interruptions occur, which can be perceived by the driver as longitudinal dynamic vibrations that affect comfort. In a manually shifted transmission, this procedure is less disadvantageous, since the driver himself pushes the shifting process and the traction force disturbance is perceived as the intended effect of the shifting process. In automated transmission designs, the driver is more or less surprised by the longitudinal dynamic vibrations caused by the gear shift. In a dual clutch transmission, the problem can be avoided by a smooth transition of closing and opening the clutch. The smooth transition can also be made under load so that no traction interruption occurs.

An electromechanical drive of this type, which has a spur gear transmission and is driven by an electric motor, is known from DE 102013207681 a 1. A spur gear transmission is formed by two spur gear stages having an input shaft and an output shaft. A spur gear stage is formed by a drive spur gear arranged on the input shaft, which meshes with a driven spur gear arranged on the output shaft. The other spur gear stage has a drive spur gear which is arranged on the input shaft and meshes with the intermediate gear, and a driven spur gear which also meshes with the intermediate gear and is arranged on the output shaft. Overrunning clutches are respectively connected between the corresponding driving cylindrical gears and the input shaft. The freewheel is used to engage one of the spur gear stages when the direction of rotation of the electric motor is changed.

Disclosure of Invention

The invention is based on the object of providing an electromechanical drive which can be operated temporarily in an energy recovery mode, which is characterized by a robust and cost-effective design and favorable mechanical operating behavior.

The object is achieved according to the invention by an electromechanical drive for a motor vehicle, having:

-an electric motor having a stator and a rotor;

a reduction gear, which is designed as a spur gear transmission and has an input shaft and an output shaft, wherein

The reduction gear has a first spur gear stage with a first gear ratio and a second spur gear stage with a second gear ratio,

the first cylindrical gear stage has a first driving cylindrical gear and a driven cylindrical gear,

a first drive cylindrical gear is arranged on the input shaft and is engaged into a first driven cylindrical gear, which is arranged on the output shaft,

the second spur gear stage has a second drive spur gear, an intermediate wheel and a second driven spur gear,

a second drive spur gear is arranged on the input shaft and engages in the intermediate wheel,

the intermediate wheel is engaged in a second driven cylindrical gear, which is arranged on the output shaft,

a first freewheel is provided between the input shaft and the first drive spur gear,

a second freewheel is provided between the input shaft and the second drive spur gear,

the first freewheel element, when the input shaft is rotated in the first rotational direction, enters the coupled state and drives the first drive wheel,

the second freewheel enters the coupled state when the input shaft rotates in a second direction of rotation opposite to the first direction of rotation and drives the second drive wheel, and

provided with a crossover clutch

For bridging the first or second freewheel, so that during freewheeling of the motor vehicle a power transmission into the input shaft can be achieved via the first or second drive spur gear.

In this way, it is advantageously possible to implement a drive in which the transmission ratio can be adapted to the vehicle speed and the current drive torque requirement with high dynamics and without significant traction force interruption due to a change in direction of the electric motor, and which furthermore enables energy to be recovered via the electric motor during a slip operation of the vehicle or also an electric reverse gear to be provided. The drive device may be designed such that it sets one of the gear stages as a gear stage for the first used standard operation. The other gear stage that can be activated by reversing the direction of rotation of the electric motor can then be a stage for very high vehicle speeds or for very high wheel drive torques.

The bridging clutch can be designed as a positively coupled clutch which can be shifted via the actuator device. The resulting coupling state can be supported in the case of a temporarily actively synchronized electric motor and a transmission section that is entrained in freewheeling by: during the induction of the coupling state, the electric motor is temporarily actively brought to the respective rotational speed, in particular very simply to the load. It then engages the freewheel corresponding to the current direction of rotation. This moment can be sensed by a simple current increase of the engine and at this moment the bridging clutch can be put into a fully synchronized state. Otherwise, the synchronization state can also be actively caused from other signals, which are generated, for example, by sensors. After switching in, the recovery power can be set by operating the stator field. The recuperation power can be set to a relatively low value first and only increased when the driver lifts his foot completely and actuates the brake. The braking power required instantaneously as a function of the brake pedal actuation force and/or the degree of brake pedal depression is then first covered accordingly via the recuperation power. The brake system continues to be active in a state where the maximum recovered power no longer covers the required braking power. In this case, the braking power of the primary drive can also be used again first, and then the actual wheel braking system becomes effective accordingly.

The bridging clutch can also be designed as a friction-fit coupling. In this case, the triggering of the coupling state can take place without active synchronization or without an appropriate shifting time. This synchronization or the approach of the desired shift time causes a reduction in the load on the bridging clutch, so that the bridging state is preferably only caused when a friction-fit coupled bridging clutch is used: sufficient, preferably actively induced, synchronicity of the system sections occurs.

According to a particular aspect of the invention, two crossover clutches are provided, so that two different gear ratios are provided for energy recovery operation. This allows the recovered power to be generated at a rotor speed range optimized for the current vehicle speed. On the one hand, the rotor can therefore be driven for energy recovery at high vehicle speeds, without the rotor having an unacceptably high rotational speed. On the other hand, it is possible to efficiently recover the kinetic energy of the vehicle approximately until the vehicle stops. In addition, a direct transition between the drive mode and the energy recovery mode can be effected with the bridging clutch closed, and the bridging clutch is only opened when a change in the transmission ratio is required. In order to disconnect the bridging clutch, the electric motor is preferably temporarily actuated in such a way that the bridging clutch can be disconnected without load.

The selection of the respective transmission ratio for the vehicle drive can accordingly involve additional information, so that, for example, when driving out of a position in an ascending lane, a stage with a higher transmission ratio is first selected by the electronic control unit, so that in a phase with coasting which is as free of load as possible, then for the additional drive the engine direction is selected in which the gear stage for the high vehicle speed assumes the power transmission. The shift stages can be shifted during a vehicle operating phase which is as free as possible from load and do not have to be specified for a specific motor speed or vehicle speed. For example, criteria for shifting between gear ratios for a relatively wide speed range may be proposed. If only a small load demand for the electric motor occurs temporarily in this region, a shift can be carried out, wherein the load demand can also be actively caused in the hybrid vehicle by correspondingly activating the primary transmission. By means of the concept according to the invention it is possible for the vehicle to have a rolling state without the rotor of the electric motor being driven, for example when the primary drive is active. Depending on the vehicle speed, it can then be decided by the control device when there is a load demand, at which gear ratio the load demand is to be met. The desired gear ratio is selected by setting the direction of rotation of the engine that generates said gear ratio. The rotors are not necessarily drawn together in the drive according to the invention, and both drive gears can pass the drive shaft without significant traction losses when driving the vehicle via the primary drive. It is also possible to select the transmission ratio as a function of the setting performed on the vehicle side. It is therefore possible to provide the driver with an input device in the region of the operating environment, by means of which the driver can select a specific "gear" and thus a specific direction of rotation of the engine, for example. Furthermore, the driver can also select a specific operating mode, for example a sport operating mode, in which a speed-optimized shift behavior is obtained, or an energy-saving mode, in which the transmission ratio is selected such that the electric motor is effective in a rotation range that is advantageous with regard to efficiency.

The drive device according to the invention can advantageously form a secondary drive for a motor vehicle, while a primary drive, for example in the form of an internal combustion engine or another electric motor, is arranged at the other axle. The primary drive can also assume functions, such as driving in reverse gear and possibly additional energy recovery, so that here, on the one hand, there is redundancy and, on the other hand, the possibility of efficiency concentration (wirkungsgaggeration), in which the two systems are active in parallel. Furthermore, in a further advantageous manner, the primary drive can "smooth-switch" possible shift pauses (in the case of a pole change of the electric motor) and traction interruptions during the shifting of the secondary drive. The secondary drive or optionally also the entire axle with the secondary drive can preferably be selectively switched off (AWD switched off, hanging clutch (Hang-On-kupplong)). For the realization of the energy recovery operation, a positive or friction-fit coupling (e.g. claw) clutch can be provided at suitable points in the drive device according to the invention in order to bridge the freewheel if required for reversing and energy recovery. The secondary drive can also be relieved of load in the case of operating states of the primary drive which have an adverse exhaust gas content, in particular in the acceleration phase of the primary drive.

The drive device according to the invention is preferably designed such that the first freewheel is arranged in the first drive gear. The second freewheel is then preferably arranged in the second drive gear. The freewheel can be designed as a positively and/or frictionally coupled freewheel. The freewheel can therefore be designed such that the initiation of the coupling state is supported also by the action of the tooth reaction forces and, for example, by an at least small axial displacement of the helically toothed drive wheel associated therewith.

The drive is preferably also designed such that a first transmission ratio is realized via the first spur gear stage, the absolute value of which is greater than the absolute value of a second transmission ratio realized via the second spur gear. In this case, then, the first drive gear has a smaller tip circle diameter than the second drive gear. However, it is also possible to coordinate the two gear ratios such that the first gear ratio is smaller in absolute value than the second gear ratio. In this case, then, the second drive gear has a smaller tip circle diameter. The span of the distance between the drive shaft and the output shaft is performed here by a gear train which is formed by the intermediate gear and the second driven gear.

According to a further preferred embodiment of the invention, the input shaft is oriented coaxially to the rotor axis or is driven directly by the rotor shaft or alternatively is formed by the rotor shaft.

Alternatively to the variant proposed above, it is also possible for the drive to be designed such that a front stage wheel is arranged on the input shaft and is then driven by a drive pinion arranged on the rotor shaft of the electric motor. A further gear mechanism, which is embodied in another way and is designed, for example, as a planetary gear mechanism, can also be arranged between the input shaft and the rotor.

In the case of a direct integration of the axle differential into the drive, the first and second driven spur gears or at least one of the gears can be arranged directly on the surrounding housing, i.e. on the cover of the axle differential. The input shaft and the output shaft are preferably oriented parallel to one another and the axle differential can be accommodated directly in the transmission housing of the drive.

The drive device is preferably designed to be arranged in the installed state in the motor vehicle such that the input shaft is oriented transversely to the longitudinal direction of the vehicle. The drive device here preferably forms an axle drive module which is arranged in the middle region between the left and right wheels. As long as the drive is used as a secondary drive, it is preferably arranged in the region of the rear axle. In vehicles with a rear or middle engine as the primary drive, the drive device according to the invention is arranged in the region of the front axle if it is a secondary drive. It is possible for the housing section of the drive device to serve as a coupling point for the wheel suspension. The housing of the drive device can be used as a rear axle carrier and provides a bearing point for a triangular suspension arm or transverse link, for example, and also for a spring mechanism, in particular a spring leg or a torsion spring.

In the drive according to the invention, two transmission stages with opposing freewheel mechanisms are formed, and at least one freewheel mechanism is selectively bridged by means of a crossover clutch. Depending on the direction of rotation of the electric machine, the force flow is effected via the first gear or via the second gear and in this case via the intermediate shaft toward the output shaft. By reversing the direction of motor rotation, it is therefore possible to shift between the two speed ratios. When the bridging clutch is activated, the vehicle can also be operated in reverse mode and in energy recovery mode in the respective engine direction of rotation.

The transmission of the drive device according to the invention comprises a drive shaft, an intermediate shaft, a driven shaft and a freewheel or overrunning clutch as preferably passive shifting elements, as well as at least one bridging clutch which is actively engaged, in particular for transmission stages with a high absolute speed ratio as an active shifting device.

In the drive according to the invention, two toothed wheels are arranged on the drive shaft, which are each connected to the drive shaft via an opposing freewheel. The gear on the output shaft is fixedly connected with the shaft. The freewheel mechanisms of the gear pairs are always of opposite design. Thus, only one gear is driven in each direction of rotation of the motor. In the first gear, the power flow takes place directly from the drive wheels to the driven wheels. In the second gear, the power flow takes place from the drive wheels via the intermediate wheels to the output wheels. The intermediate wheel compensates for the reversal of the direction of rotation of the motor and the driven wheel is therefore driven again in the correct direction of rotation. Therefore, gear changes during reversal of the direction of rotation of the electric machine are possible.

The first spur gear pair is formed by a first gear module arranged on the drive shaft or intermediate shaft together with a first driven wheel on the driven shaft. The second spur gear pair is formed by a second gear module on the drive shaft/intermediate shaft together with a counter wheel (intermediate wheel). The third spur gear pair is formed by the meshing of a counter wheel (intermediate wheel) and a second output wheel on the output shaft. The corresponding spur gear module is composed of a gear and a free wheel mechanism. The two freewheel mechanisms block each other. The rolling bearing is preferably located next to the freewheel. The output shaft is preferably at the same time a cover, a web or a surrounding housing provided as a differential for the power branch. The differential can be designed in a particularly advantageous manner as a spur gear differential or bevel gear differential.

The gear ratios of the two stages can be adjusted such that they can also be used particularly advantageously to suit a particular application scenario. Thus, a high gear level may be optimized for efficiency of operation within a city, for example designed for operation at vehicle speeds up to 60km/h, and a low gear level designed for operation outside of a closed dwelling. Preferably, the stage comprising the intermediate wheel is used for statistically less frequent applications, so that the power guidance via the intermediate wheel additionally into the output gear takes place less frequently than in a stage directly engaging into the output gear via the drive gear.

Drawings

Other details and features of the invention will appear from the following description taken in conjunction with the accompanying drawings. The figures show:

fig. 1a shows a schematic diagram for illustrating the configuration of an electromechanical drive according to the invention with a bridging clutch arranged in a first transmission stage according to a first embodiment of the invention;

fig. 1b shows a schematic diagram for illustrating the configuration of an electromechanical drive device according to the invention, similar to the variant according to fig. 1a, but with a bridging clutch provided in the second transmission stage;

fig. 2 shows a schematic diagram for illustrating the configuration of an electromechanical drive according to the invention with an axle differential integrated into the output shaft and two bridging clutches for selectively bridging a first or a second transmission stage according to a second embodiment of the invention;

fig. 3 shows a schematic diagram for illustrating the configuration of an electromechanical drive according to the invention according to a third embodiment of the invention, which likewise has an axle differential integrated into the output shaft, a front-stage transmission arranged between the electric motor and the input shaft, and a friction-fit coupled bridging clutch, which here enables, for example, a freewheel bridging the second transmission stage.

Detailed Description

Fig. 1a shows a first preferred embodiment of the electromechanical drive device according to the invention for a motor vehicle. The drive device includes: an electric motor E having a stator S and a rotor R; and a reduction gear G which is designed as a spur gear and which has an input shaft EW and an output shaft AW.

The gear unit G comprises a first spur gear stage GS1 with a first gear ratio i1 and a second spur gear stage GS2 with a second gear ratio i 2. The first spur gear stage GS1 has a first drive spur gear S1A and a first driven spur gear S1B. A first drive spur gear S1A is disposed on the input shaft EW and is engaged into a first driven spur gear S1B disposed on the output shaft AW.

The second spur gear stage GS2 has a second drive spur gear S2A, an intermediate gear S2Z and a second driven spur gear S2B. A second drive spur gear S2A is arranged on the input shaft EW and engages here in the intermediate wheel S2Z. The intermediate wheel S2Z engages radially from the outside into a second drive spur gear S2B, which is arranged on the output shaft AW.

In the drive device according to the present invention, a first freewheel FR1 is provided between the input shaft EW and the first drive spur gear S1A. Further, a second freewheel FR2 is provided between the input shaft EW and the second drive spur gear S2A. The first freewheel 1 enters the coupled state in the first rotational direction of the input shaft EW, and the second freewheel 2 enters the coupled state in the rotational direction opposite to the first rotational direction of the input shaft EW. Furthermore, the bridging clutch UK is provided for bridging the first freewheel FR1, so that a power transmission into the input shaft EW can be realized during freewheeling of the motor vehicle or in order to provide a reverse gear function via the first drive spur gear S1A.

The bridging clutch UK is in this case designed as a positively coupled dog clutch, and in the engaged state the first drive spur gear S1A is coupled in a torsionally rigid manner to the input shaft EW. The bridging clutch UK is placed in the required switching state via the actuator device OP. The actuator device OP is actuated via a control device C, which also actuates the electric motor E and takes into account the rotational speeds of the input shaft EW and the output shaft AW.

The first freewheel mechanism FR1 is provided in the first drive gear S1A. The second free-wheel mechanism FR2 is provided in the second drive gear S2A. A first gear ratio i1 is achieved via the first spur gear stage GS1, the absolute value of which is greater in this embodiment than the absolute value of the second gear ratio i2 achieved via the second spur gear stage GS 2.

In this exemplary embodiment, the input shaft EW is aligned coaxially with the rotor axis X of the electric motor E, and the input shaft EW is driven directly by the rotor shaft RW or is also formed directly by the rotor shaft RW.

Fig. 1b shows a diagram of another embodiment of the electromechanical drive device according to the invention for a motor vehicle. The drive device includes: an electric motor E having a stator S and a rotor R; the speed reducer G is a cylindrical gear transmission mechanism; and an input shaft EW and an output shaft AW.

In the drive device according to the present invention, a first freewheel FR1 is provided between the input shaft EW and the first drive spur gear S1A. Further, a second freewheel FR2 is provided between the input shaft EW and the second drive spur gear S2A. The first freewheel 1 enters the coupled state in the first rotational direction of the input shaft EW, and the second freewheel 2 enters the coupled state in the rotational direction opposite to the first rotational direction of the input shaft EW. Furthermore, the bridging clutch UK is provided for bridging the second freewheel FR2, so that during freewheeling of the motor vehicle a power transmission into the input shaft EW can be achieved via the second drive spur gear S2A.

The bridging clutch UK is in this case designed as a positively coupled dog clutch, and in the engaged state the second drive spur gear S2A is coupled in a torsionally rigid manner to the input shaft EW. The bridging clutch UK is placed in the required switching state via the actuator device OP. The actuator device OP is actuated via a control device, not shown here, which also actuates the electric motor E and takes into account the rotational speeds of the input shaft EW and the output shaft AW.

In this embodiment, the input shaft EW is oriented coaxially with the rotor axis X of the electric motor E. The input shaft EW is driven directly by the rotor shaft RW or is also formed directly by the rotor shaft RW.

Fig. 2 shows a further exemplary embodiment of an electromechanical drive device according to the present invention for a motor vehicle, which can be integrated into the motor vehicle as a front or rear axle drive unit.

The drive device again comprises: an electric motor E having a stator S and a rotor R; the speed reducer G is a cylindrical gear transmission mechanism; and an input shaft EW and an output shaft AW. The gear unit G also comprises a first spur gear stage GS1 with a first gear ratio and a second spur gear stage GS2 with a second gear ratio. The first spur gear stage GS1 has a first drive spur gear S1A and a first driven spur gear S1B. A first drive spur gear S1A is disposed on the input shaft EW and is engaged into a first driven spur gear S1B disposed on the output shaft AW.

In the drive device according to the present invention, a first freewheel FR1 is provided between the input shaft EW and the first drive spur gear S1A. Further, a second freewheel FR2 is provided between the input shaft EW and the second drive spur gear S2A. The first freewheel 1 enters the coupled state in the first rotational direction of the input shaft, and the second freewheel FR2 enters the coupled state in the rotational direction opposite to the first rotational direction of the input shaft.

Furthermore, the drive comprises a first bridging clutch UK for bridging the first freewheel FR1, so that a power transmission into the input shaft EW can be achieved via the first drive spur gear S1A during freewheeling in the motor vehicle. The drive furthermore comprises a second bridging clutch UK2 for bridging the second freewheel FR2, so that during freewheeling of the motor vehicle a power transmission into the input shaft EW can be achieved via the second drive spur gear S2A.

The first bridging clutch UK and the second bridging clutch UK2 are in turn designed, for example, as form-fitting dog clutches and, in the engaged state, couple the first or second drive spur gear S1A, S2A associated therewith in a torsionally rigid manner to the input shaft EW. The first and second bridging clutches UK and UK2 are each placed in the required shift state via the actuator device OP. The actuator device OP is actuated via a control device, not shown in detail here, which also actuates the electric motor E and takes into account the rotational speeds of the input shaft EW and the output shaft AW.

The first freewheel mechanism FR1 is provided in the first drive gear S1A. The second free-wheel mechanism FR2 is provided in the second drive gear S2A. A first gear ratio is realized via the first spur gear GS1, the absolute value of which is greater in this embodiment than the absolute value of the second gear ratio i2 realized via the second spur gear stage GS 2.

In this embodiment, the input shaft EW is also oriented coaxially with the rotor axis X of the electric motor E. The input shaft EW is driven directly by the rotor shaft RW or is also formed directly by the rotor shaft RW.

In contrast to the variant according to fig. 1a and 1b, the axle differential AD, which is now used to branch off the drive power to the left and right wheel drive shafts WSL, WSR, is integrated into the drive device in such a way that its surrounding housing ADH serves as a carrier for the driven shaft AW and the two driven gears S1B, S2B. The axle differential AD is preferably designed as a spur gear differential or bevel gear differential.

The input shaft EW and the output shaft AW are oriented parallel to each other. The drive is arranged in the installed state in the motor vehicle such that the input shaft EW is oriented transversely to the longitudinal direction of the vehicle. The drive device can form an axle drive module which is arranged in the central region between the left and right wheels LW, RW.

The illustration according to fig. 3 shows a third exemplary embodiment of an electromechanical drive device according to the invention for a motor vehicle, which in turn can be integrated into a motor vehicle as a front axle drive unit or as a rear axle drive unit.

Furthermore, the drive comprises a bridging clutch UK for bridging the second freewheel FR2, so that a power transmission into the input shaft EW can be achieved via the second drive spur gear S2A during freewheeling in the motor vehicle.

The bridging clutch UK is designed here, for example, as a friction-fit coupling, in particular as a multiplate clutch, and in the engaged state the second drive spur gear S2A is coupled in a rotationally rigid manner to the input shaft EW. The bridging clutch UK is placed in the required shift state via an actuator device, which is not further shown here. The actuator device is actuated as already described in relation to fig. 1b via a control device which also actuates the electric motor E and takes into account the rotational speeds of the input shaft EW and the output shaft AW.

The first freewheel mechanism FR1 is provided in the first drive gear S1A. The second free-wheel mechanism FR2 is provided in the second drive gear S2A. A first gear ratio is realized via the first spur gear stage GS1, the absolute value of which is greater than the absolute value of a second gear ratio realized via the second spur gear stage GS 2.

In contrast to the exemplary embodiment according to fig. 1 and 2, in this exemplary embodiment the input shaft EW is not oriented coaxially to the rotor axis X of the electric motor E, but is offset parallel thereto. The input shaft EW is indirectly driven with the prestage GS3 engaged. The prestage GS3 comprises a spur gear S3A which is driven directly by the rotor shaft RW and furthermore has a spur gear S3B which is arranged on the input shaft EW and engages with the spur gear S3A.

In contrast to the variant according to fig. 1 and in the same way as the variant according to fig. 2, the axle differential AD, which is now used to branch off the drive power to the left and right wheel drive shafts WSL, WSR, is inserted into the drive device in such a way that its surrounding housing ADH serves as a carrier for the driven shaft AW and the two driven gears S1B, S2B. The axle differential AD is again preferably, although shown differently as a bevel gear differential, designed as a cylindrical gear differential.

The input shaft EW and the output shaft AW are oriented parallel to each other. The drive is designed to be arranged in the installed state in the motor vehicle such that the input shaft EW is oriented transversely to the longitudinal direction of the vehicle. The drive device can form an axle drive module which is arranged in the central region between the left and right wheels LW, RW.

The freewheel mechanisms FR1, FR2 oriented opposite one another are brought into the coupled state or the freewheel state depending on the direction of rotation of the rotor R of the electric motor E. The freewheel mechanisms FR1, FR2 can be designed as friction-and/or form-fit coupled freewheel mechanisms. It is possible that the free-wheel mechanisms FR1, FR2 are also realized in axial displaceability in cooperation with the spur gear. For example, the freewheel can be designed such that it initially carries the gear wheel associated therewith as a friction-fit coupling. In this case, the gear wheel is then displaced axially as a result of the gear wheel reaction force, i.e. the correspondingly designed axial force of the inclined toothing, and thus also has a form-fitting coupling state with its drive shaft. This results in a particularly high torque transmission capability and a reduction of the friction-coupled freewheel. Conversely, the locked free-wheel mechanisms FR1, FR2 can also be arranged in the lateral region of the respective spur gear and in this case cause a torque transmission between the spur gears S1A, S2A and the laterally adjacent flange portion of the input shaft EW. The crossover clutch may also be implemented in cooperation with the corresponding drive gear S2A (and also S1A). The method is characterized in that: the lateral regions of the gear wheels or the hub regions thereof serve to form a coupling structure, and the gear wheels may also serve as shifting elements that can be axially displaced on the input shaft.

It is also possible in the exemplary embodiments described above for the intermediate wheel S2Z provided and used for reversing the direction of rotation to be designed as an axially longer gear wheel or as a stepped gear wheel. This is inserted into the drive, so that it or a step coaxial therewith likewise engages in the first output gear S1B. The second driven gear S2B can be eliminated. It is also possible for the first and second driven gears S1B, S2B to be of identical construction and then, via the intermediate gear S2Z, to form a gear set for the second drive gear S2A. The second drive gear S2A then has a smaller tip circle radius than the first drive gear S1A. In this case, a transmission ratio of greater absolute value is then achieved via the second spur gear stage GS 2. It is also possible to dispense with the first freewheel FR1 and to couple and decouple the first drive gear S1A to the input shaft exclusively by actuating the first bridging clutch UK.

According to a further aspect of the invention, it is also possible in an advantageous manner that the two spur gear stages GS1, GS2 are designed such that the axis X2 of the idler gear S2Z also lies in an axial plane defined by the axes XEW, XAW of the input shaft EW and the output shaft AW. This measure is particularly advantageous for realizing a transmission housing in the form of a basin, not shown here. If the transmission housing is realized in the manner of a pot, the axis X2 of the intermediate wheel S2Z is also offset parallel to the above-mentioned plane. The input shaft EW and the output shaft AW, in particular when they carry the axle differential AD, are then preferably inserted into the transmission housing from the sides lying opposite one another. The transmission housing can be closed on the side of the electric motor E by a closing flange of the electric motor or also by a housing section which carries the front-stage transmission GS3 itself. The front-mounted gear unit GS3 can also be realized in a different manner, in particular as a planetary gear unit.

In a broad sense, the invention resides in an electromechanical drive for a motor vehicle, having: two spur gear stages, which form parallel power transmission paths with different gear ratios, are coupled kinematically to the electric motor with the interposition of oppositely oriented freewheel elements, so that a power transmission to the transmission output, in particular to an integrated axle differential, can be activated by selecting the direction of rotation of the electric motor, and furthermore at least one of the freewheel elements can be bridged selectively by means of a crossover clutch.

Claims

1. An electromechanical drive device for a motor vehicle, comprising:

-an electric motor (E) having a stator (S) and a rotor (R);

a reduction gear (G) which is designed as a spur gear transmission and has an input shaft (EW) and an output shaft (AW), wherein

-the gear unit (G) has a first spur gear stage (GS1) with a first gear ratio and a second spur gear stage (GS2) with a second gear ratio,

-the first cylindrical gear stage (GS1) has a first driving cylindrical gear (S1A) and a first driven cylindrical gear (S1B),

-said first driving cylindrical gear (S1A) is placed on said input shaft (EW) and engaged into said first driven cylindrical gear (S1B) placed on said output shaft (AW),

-the second spur gear stage (GS2) has a second driving spur gear (S2A), an intermediate gear (S2Z) and a second driven spur gear (S2B),

-the second drive cylindrical gear (S2A) is placed on the input shaft (EW) and is engaged here into the intermediate wheel (S2Z),

-the intermediate wheel (S2Z) is engaged into the second driven spur gear (S2B) which is disposed on the output shaft (AW),

-a first freewheel (FR1) is provided between the input shaft (EW) and the first drive spur gear (S1A),

-a second freewheel (FR2) is provided between the input shaft (EW) and the second drive spur gear (S2A),

-the first freewheel (FR1) is brought into a coupled state when the input shaft (EW) is rotated in a first direction of rotation,

-said second freewheel (FR2) is brought into a coupled state when said input shaft (EW) rotates in a second direction of rotation opposite to said first direction of rotation, and

-a bridging clutch (UK) is provided for bridging the first and/or second freewheel (FR1, FR2) such that a power transmission into the input shaft (EW) is possible via the first and/or second drive spur gear (S1A, S2A) during freewheeling of the motor vehicle.

2. The electromechanical drive device according to claim 1,

it is characterized in that the preparation method is characterized in that,

the bridging clutch (UK) is designed as a positively coupled clutch, and an actuator device (OP) is provided for setting a switching state of the bridging clutch (UK).

3. The electromechanical drive device according to claim 1 or 2,

it is characterized in that the preparation method is characterized in that,

setting of the coupling state of the bridging clutch (UK) is supported with a temporary active synchronization of the electric motor (E) and the transmission section driven in freewheeling by: the electric motor (E) is temporarily actively brought to a corresponding rotational speed or light load during the induction of the coupling state.

4. The electromechanical drive device according to claim 1 or 3,

it is characterized in that the preparation method is characterized in that,

the bridging clutch (UK) is designed as a friction-coupled clutch.

5. The electromechanical drive device according to at least one of claims 1 to 4,

it is characterized in that the preparation method is characterized in that,

a bridging state is caused when sufficient synchronicity of the system sections to be coupled by means of the bridging clutch (UK) occurs.

6. The electromechanical drive device according to at least one of claims 1 to 5,

it is characterized in that the preparation method is characterized in that,

two bridging clutches (UK, UK2) are provided, so that two different transmission ratios are provided for the energy recovery operation.

7. The electromechanical drive device according to at least one of claims 1 to 6,

it is characterized in that the preparation method is characterized in that,

the electromechanical drive device comprises an Axle Differential (AD) for branching off the drive power conducted via a reduction gear (G) to a first and a second wheel drive shaft (WSL, WSR), and the Axle Differential (AD) is arranged coaxially to the output shaft (AW), wherein the Axle Differential (AD) comprises a surrounding housing (ADH) and the surrounding housing (ADH) forms part of the output shaft (AW) and carries the first driven gear (S1B) and/or the second driven gear (S2B) there.

8. The electromechanical drive device according to at least one of claims 1 to 7,

it is characterized in that the preparation method is characterized in that,

the first freewheel (FR1) is arranged in a first drive gear (S1A) and the second freewheel (FR2) is arranged in the second drive gear (S2A).

9. The electromechanical drive device according to at least one of claims 1 to 8,

it is characterized in that the preparation method is characterized in that,

a first gear ratio is achieved via the first spur gear stage (GS1), the absolute value of which is greater than the absolute value of a second gear ratio achieved via the second spur gear stage (GS 2).

10. The electromechanical drive device according to at least one of claims 1 to 9,

it is characterized in that the preparation method is characterized in that,

the input shaft (EW) is coaxially oriented with respect to the axis of rotation (X) and/or is directly driven by the rotor shaft (RW) or is formed by the rotor shaft (RW).