ELECTRIC DRIVE FOR A MOTOR VEHICLE

Abstract

Electric drive for a motor vehicle, comprising a first electric motor (4) designed to continuously generate a base power during driving operation, and a second electric motor (6) designed to temporarily generate a boost power during driving operation, wherein the first electric motor (4) and the second electric motor (6) differ from each other with respect to one or more of the following characteristics: design type, maximum torque, maximum power, rotor diameter, axial length, maximum rotational speed.

Description

[0001] The present invention relates to an electric drive for a motor vehicle.

[0002] In conventional electric drives, identical electric motors are used, which can be selected to provide either base power or boosting. However, the "base power" and "boosting" functions place fundamentally different demands on the required speed and torque. Therefore, identical electric motors intended for both base load and boosting always represent a compromise regarding the overall efficiency of the electric drive.

[0003] The present invention addresses the technical problem of providing an improved electric drive for a motor vehicle. This problem is solved by the features of the independent claim. Further embodiments of the invention are described in the dependent claims and the following description.

[0004] According to the invention, an electric drive for a motor vehicle is provided, comprising a first electric motor designed to continuously generate a base power during driving operation, and a second electric motor designed to temporarily generate a boost power during driving operation, wherein the first electric motor and the second electric motor differ from each other with respect to one or more of the following characteristics: design type, maximum torque, maximum power, rotor diameter, axial length, maximum speed.

[0005] The electric drive in question enables more efficient driving operation, in which the motors are designed with regard to their specific tasks, namely the generation of a continuous basic power output on the one hand and the generation of a point-in-time, i.e. temporary, boost power output on the other.

[0006] Each of the two motors can therefore be dimensioned or selected in such a way that the motor in question can be operated as frequently as possible at an operating point with high efficiency.

[0007] When referring to a different design type of the two electric motors, the different designs of the electric motors are selected from the following types: permanent magnet synchronous motor, axial flux motor, asynchronous motor, synchronous reluctance motor, separately excited synchronous motor.

[0008] According to one embodiment of the electric drive, it can be provided that a first gearbox is assigned to the first electric motor, wherein the first gearbox is configured to translate a speed and torque of the first electric motor, wherein the first gearbox has at least two or exactly two gears, wherein the first gearbox is in particular connected to the first electric motor by means of an additional gear stage.

[0009] It may be provided that a second gearbox is assigned to the second electric motor, wherein the second gearbox is configured to translate a speed and torque of the second electric motor, wherein the second gearbox has at least two or exactly two gears, wherein the second gearbox is in particular connected to the second electric motor by means of an additional gear stage.

[0010] According to one embodiment of the electric drive, it can be provided that the gears of the first transmission have gear ratios that are different from the gear ratios of the gears of the second transmission.

[0011] It may be provided that the drive power of the first electric motor and the drive power of the second electric motor are introduced into an axle differential, wherein a first output shaft of the axle differential is assigned a first auxiliary gearbox to translate an output speed and an output torque of the axle differential, and wherein a second output shaft of the axle differential is assigned a second auxiliary gearbox to translate an output speed and an output torque of the axle differential.

[0012] According to one embodiment of the electric drive, it may be provided that the first auxiliary gearbox is a voltage wave gearbox or a planetary gearbox and / or the second auxiliary gearbox is a voltage wave gearbox or a planetary gearbox.

[0013] It may be provided that the first electric motor and the second electric motor can be switched on independently of each other.

[0014] It can be provided that the first electric motor and the second electric motor are oriented in the same direction or in opposite directions to each other, i.e. their output shafts extend in the same direction or in opposite directions.

[0015] According to one embodiment of the electric drive, a third electric motor may be provided, which forms a steering drive for driving a counter-rotating gearbox, wherein the counter-rotating gearbox is connected to the first and second auxiliary gearboxes.

[0016] It may be provided that two or more coupling elements are provided in order to decouple individual components from a power flow to generate the total output power or to couple them into the power flow.

[0017] The first gearbox may be assigned a clutch element for decoupling from or coupling into the power flow.

[0018] The second gearbox may be assigned a clutch element for decoupling from or coupling into the power flow.

[0019] The first auxiliary gearbox may be assigned a clutch element for decoupling from or coupling into the power flow.

[0020] The second auxiliary gearbox may be assigned a clutch element for decoupling from or coupling into the power flow.

[0021] A coupling element can be assigned to the differential for decoupling from or coupling into the power flow.

[0022] The first electric motor may be assigned a coupling element for decoupling from or coupling into the power flow.

[0023] The second electric motor may be assigned a coupling element for decoupling from or coupling into the power flow.

[0024] The electric drive can have an eddy current brake. The eddy current brake can be located on a motor shaft. The motor shaft can be that of the first electric motor or the second electric motor. Each electric motor can have its own eddy current brake.

[0025] The invention is described in more detail below with reference to an exemplary embodiment shown in a drawing. The drawing schematically depicts: Fig. 1 a first electric drive according to the invention; Fig. 2 a second electric drive according to the invention; Fig. 3 a third electric drive according to the invention; Fig. 4 a fourth electric drive according to the invention.

[0026] Fig. Figure 1 shows an electric drive 2 for a motor vehicle.

[0027] The electric drive 2 has a first electric motor 4, which is designed to continuously generate a base power during driving operation.

[0028] The electric drive 2 has a second electric motor 6, which is designed to temporarily generate boost power during driving.

[0029] The first electric motor 4 and the second electric motor 6 differ from each other with respect to one or more of the following characteristics: design type, maximum torque, maximum power, rotor diameter, axial length, maximum speed.

[0030] The first electric motor 4 is assigned a first gearbox 8.

[0031] The first gearbox 8 is designed to transmit the rotational speed and torque of the first electric motor 4. The first gearbox 8 has exactly two gears 10 and 12, which can be selected by means of a first shift element 14.

[0032] A second gearbox 16 is assigned to the second electric motor 6.

[0033] The second gearbox 16 is designed to transmit the rotational speed and torque of the second electric motor 6. The second gearbox 16 has exactly two gears 18 and 20, which can be selected by means of a second shift element 22.

[0034] The first electric motor 4 is arranged coaxially to an input shaft 19 of the first gearbox 8.

[0035] The second electric motor 6 is arranged coaxially to an input shaft 21 of the second gearbox 16.

[0036] Gears 10 and 12 of the first gearbox 8 have gear ratios that differ from the gear ratios of gears 18 and 20 of the second gearbox 16.

[0037] The drive power of the first electric motor 4 and the drive power of the second electric motor 6 are introduced into an axle differential 24.

[0038] The axle differential 24 is driven by the gearboxes 8 and 16 via a single gear 25.

[0039] A first output shaft 26 of the axle differential 24 is assigned a first auxiliary gearbox 28 to translate an output speed and output torque of the axle differential 24.

[0040] A second auxiliary gearbox 32 is assigned to a second output shaft 30 of the axle differential 24 in order to translate an output speed and an output torque of the axle differential 24.

[0041] The first auxiliary gearbox 28 is a planetary gearbox. The second auxiliary gearbox 32 is a planetary gearbox.

[0042] The first electric motor 4 and the second electric motor 6 can be switched on independently of each other.

[0043] Coupling elements may be provided to decouple individual components from a power flow for generating the total output power or to couple them into the power flow.

[0044] On the output side, wheels 34 and 36 are shown here as examples and schematically. In this way, running wheels for road use or drive wheels for tracks of tracked vehicles can be driven.

[0045] Fig. Figure 2 shows a second electric drive 38 according to the invention. To avoid repetition, only the differences to the embodiment described above will be discussed below, with the same reference numerals assigned to the same features.

[0046] The second electric drive 38 differs from the first electric drive 2 described above in that the second electric drive 38 has additional gear stages on the motor side.

[0047] The first gearbox 8 is connected to the first electric motor 4 by means of a first additional gearbox stage 40.

[0048] The second gearbox 16 is connected to the second electric motor 6 by means of a second additional gearbox stage 42.

[0049] The first electric motor 4 is therefore not arranged coaxially, but parallel to the input shaft 19 of the first gearbox 8.

[0050] The second electric motor is therefore not arranged coaxially, but parallel to the input shaft 21 of the second gearbox 16.

[0051] Fig. Figure 3 shows a third electric drive 44 according to the invention. To avoid repetition, only the differences to the previously described embodiment will be discussed below, with the same reference numerals assigned to the same features.

[0052] The third electric drive 44 differs from the first electric drive 2 described above in that a third electric motor 46 is provided, which forms a steering drive for driving a counter-rotating gearbox 48, wherein the counter-rotating gearbox 48 is connected to the first and second auxiliary gearboxes 28, 32.

[0053] Fig. Figure 4 shows a fourth electric drive 50 according to the invention. To avoid repetition, only the differences from the previously described embodiment will be discussed below, with the same reference numerals assigned to the same features.

[0054] The fourth electric drive 50 differs from the first electric drive 2 described above in that a third electric motor 46 is provided, which forms a steering drive for propulsion. The rotating gearbox 52 is directly connected at one end to the auxiliary gearbox 32 and via a counter-rotating gearbox to the auxiliary gearbox 28.

Claims

[1] Electric drive for a motor vehicle, - with a first electric motor (4) which is designed to continuously generate a base power during driving operation, - with a second electric motor (6) which is set up to temporarily generate boost power during driving operation, - wherein the first electric motor (4) and the second electric motor (6) differ from each other with respect to one or more of the following characteristics: design type, maximum torque, maximum power, rotor diameter, axial length, maximum speed. [2] Electric drive according to claim 1, characterized by, that a first transmission (8) is associated with the first electric motor (4), wherein the first transmission (8) is configured to translate a speed and torque of the first electric motor (4), wherein the first transmission (8) has at least two or exactly two gears (10, 12), wherein the first transmission (8) is in particular connected to the first electric motor (4) by means of an additional transmission stage (40). [3] Electric drive according to one of the preceding claims, characterized by , that a second transmission (16) is associated with the second electric motor (6), wherein the second transmission (16) is configured to translate a speed and torque of the second electric motor (6), wherein the second transmission (16) has at least two or exactly two gears (18, 20), wherein the second transmission (16) is in particular connected to the second electric motor (6) by means of an additional transmission stage (42). [4] Electric drive according to claim 2 and claim 3, characterized by , that the gears (10, 12) of the first transmission (8) have gear ratios that are different from the gear ratios of the gears (18, 20) of the second transmission (16). [5] Electric drive according to one of the preceding claims, characterized by , that the drive power of the first electric motor (4) and the drive power of the second electric motor (6) are introduced into an axle differential (24), wherein a first auxiliary transmission (28) is assigned to a first output shaft (26) of the axle differential (24) to translate an output speed and output torque of the axle differential (24), and wherein a second auxiliary transmission (32) is assigned to a second output shaft (30) of the axle differential (24) to translate an output speed and output torque of the axle differential (24). [6] Electric drive according to one of the preceding claims, characterized by, that the first auxiliary gear (28) is a voltage shaft gear or a planetary gear and / or the second auxiliary transmission (32) is a voltage wave transmission or a planetary transmission. [7] Electric drive according to one of the preceding claims, characterized by , that the first electric motor (4) and the second electric motor (6) can be switched on independently of each other and / or the first electric motor (4) and the second electric motor (6) are oriented in the same direction or in opposite directions to each other. [8] Electric drive according to one of the preceding claims, characterized by that an eddy current brake is provided, in particular that the eddy current brake is provided on a motor shaft. [9] Electric drive according to claim 5, characterized by, that a third electric motor (46) is provided which forms a steering drive for driving a counter-rotating gearbox (48, 52), wherein the counter-rotating gearbox is connected to the first and second auxiliary gearboxes (28, 32). [10] Electric drive according to one of the preceding claims, characterized by that two or more coupling elements are provided to decouple individual components from a power flow to generate the total output power or to couple them into the power flow.

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