Powertrain and motor vehicle

Abstract

The invention relates to a drive train (2) for a motor vehicle (1) having a first axle (3) and a second axle (4), wherein the first axle (3) has an electric drive device as the drive device (6) and the second axle (4) has an externally excited synchronous machine (13) as the drive device (12), characterized in that the first axle (3) is designed to be clutch-free. The invention also relates to a motor vehicle.

Description

[0001] The invention relates to a drive train for a motor vehicle having a first axle and a second axle, wherein the first axle has an electric drive device as the drive device and the second axle has a separately excited synchronous machine as the drive device.

[0002] DE 10 2022 003 151 B3 discloses a method for operating an electric drive system for a motor vehicle, which enables energy-saving operation. A permanent-magnet synchronous motor and a separately excited synchronous motor are used, whereby the permanent-magnet synchronous motor can be decoupled from a front wheel using a separating clutch.

[0003] Based on this, it is the object of the present invention to provide a drive train which has a simpler structure.

[0004] To solve this problem, a drive train with the features of claim 1 is proposed.

[0005] The drivetrain according to the invention has at least two axles. An axle typically has at least one output shaft. Two or more wheels can be attached to the axle, but these are not part of the axle. Furthermore, axles can have a differential, but do not have to. Rigid axles are particularly common in the commercial vehicle sector.

[0006] Preferably, the drive train has exactly two axles. The first axle, like the second axle, is electrically driven. The second axle has a separately excited synchronous motor as its drive device.

[0007] Electrical drive systems include permanent magnet synchronous motors, asynchronous motors, and separately excited synchronous motors. The drive system for the first axis is freely selectable, while the drive system for the second axis is fixed.

[0008] Furthermore, the first axle is designed to be clutchless. This allows for a compact design while still allowing for energy-efficient operation.

[0009] In other words, clutchless means that the drive unit is permanently connected to the ends of the output shafts or wheels. When the drive unit is operating, torque is also transmitted.

[0010] With this arrangement, the drive unit cannot be decoupled. However, one of the drive units is the primary drive unit anyway, i.e., the one used to drive the vehicle all or most of the time. In this case, it is actually more efficient overall to not provide a clutch and, if necessary, to accept the drag torque of the first axle's drive unit than to provide a decoupler.

[0011] These drive devices are also called traction drives. They drive the axles.

[0012] Advantageously, the second axle can also be designed without a clutch. Additional axles can also be designed without a clutch. In this case, the entire drive train is designed without a clutch.

[0013] Preferably, the first axle can have a permanent-magnet synchronous machine as its drive device. A permanent-magnet synchronous machine offers the advantage of being more efficient than a separately excited synchronous machine, thus achieving a higher yield of the available battery energy.

[0014] Alternatively, the first axle can have a separately excited synchronous motor as its drive device. In this case, the drive train comprises two separately excited synchronous motors. These are preferably equipped with different operating parameters, so that the more efficient separately excited synchronous motor can be selected for different operating points.

[0015] Alternatively, the first axis can be driven by an asynchronous motor. The first axis can then also be operated as a generator, for example.

[0016] Advantageously, the separately excited synchronous motor of the second and / or first axle can have an inductive transformer for power transmission. Contactless power transmission minimizes drag torque. This allows the separately excited synchronous motor to be decoupled from the drive train without the need for a separating coupling when power is not supplied.

[0017] Preferably, the drive device of the first axis can be arranged parallel to the axis. Alternatively, the drive device of the first axis can be arranged coaxially. This allows for optimal use of installation space.

[0018] Advantageously, the drive device of the second axis can be arranged parallel to the axis. This allows the second axis to be manufactured cost-effectively.

[0019] Preferably, the drive device of the first axle can have a higher peak power and / or continuous power than the separately excited synchronous motor of the second axle. In particular, the first axle can be operated as the primary axle. The primary axle preferably covers all driving ranges with low to high power requirements, in particular, it covers these alone.

[0020] The secondary axle, preferably the second axle in this case, is used additionally when particularly high drive power is required. Due to the power curve of the separately excited synchronous motor, this can be particularly advantageous during sprints at higher speeds, such as overtaking on the highway.

[0021] Advantageously, the first axle can be arranged as the front axle. In this case, the second axle is arranged as the rear axle. If there are more than two axles, the second axle can also be arranged as the middle axle. The other axles can also be electrically driven and, in particular, also have separately excited synchronous motors.

[0022] Alternatively, the first axle can be arranged as the rear axle. In this case, the second axle is arranged as the front axle.

[0023] Preferably, the separately excited synchronous machine of the second axis can be operated with a continuous speed of over 10000 min -1 This ensures an efficiency range that optimally covers all operating situations. High speeds correspond to high power in a separately excited synchronous machine.

[0024] Preferably, the first axis has an inverter. Preferably, the second axis has an inverter. Then, each drive device can be operated independently. By arranging them on each axis, a compact design can be achieved.

[0025] Advantageously, the first axis can have a gear for varying the speed of the drive device. Alternatively or additionally, the second axis can have a gear for varying the speed of the separately excited synchronous machine. The output of the motor shaft, in particular the rotor, of the drive device is torque-coupled to the gear.

[0026] The transmission of the first axle and / or the second axle can be designed as a planetary gear. Alternatively, the transmission of the first axle and / or the second axle can be designed as a spur gear. Further alternatively, the transmission of the first axle and / or the second axle can comprise both a planetary gear and a spur gear.

[0027] Advantageously, the first axle can have a differential. Alternatively or additionally, the second axle can have a differential. In one embodiment, the first axle has a differential, and the second axle is designed without a differential.

[0028] Advantageously, the first axle and / or the second axle can have an integrated differential. In this case, the transmission for varying the speed of the drive device and the differential are designed as a single transmission.

[0029] Advantageously, the mass of the second axle drive can be less than 80% of the mass of the first axle drive. The axle drive includes the drive device, an inverter, the transmission, and the differential, if present. Preferably, the mass of the second axle drive can be less than 70% of the mass of the first axle drive.

[0030] The invention also relates to a motor vehicle with a drive train. The motor vehicle is characterized in that the drive train is designed as described.

[0031] Further advantages, features, and details of the invention will become apparent from the following description of exemplary embodiments and figures. These show: Fig. 1 a motor vehicle, Fig. 2 a schematic representation of a circuit of a separately excited synchronous machine, and Fig. 3 a schematic representation of an electrical machine of a separately excited synchronous machine.

[0032] Fig. 1 shows a motor vehicle 1 with a drive train 2 having a first axle 3 and a second axle 4. The first axle 3 has an electric axle drive 5. The electric axle drive 5 has a permanent-magnet synchronous machine 7 as the drive device 6. A transmission 8 is also shown. Not shown is an inverter of the first axle 3, which may also be present. The transmission 8 can be configured as a transmission for varying the speed of the permanent-magnet synchronous machine 7 and / or as a differential and / or as an integrated differential.

[0033] Preferably, the permanent magnet synchronous machine 7 is arranged coaxially.

[0034] Two output shafts 9 lead from the gearbox 8 and are coupled to the wheels 10.

[0035] The first axle 3 is designed without a coupling.

[0036] The second axle 4 has an electric axle drive 11 with a drive device 12 which is designed as a separately excited synchronous machine 13.

[0037] The separately excited synchronous machine 13 is coupled to the output shaft 15 via a gearbox 14. In principle, the gearbox 14 can be designed like the gearbox 8. Preferably, the gearbox 14 is designed to be differential-free, i.e., it only has a gearbox for changing the speed of the separately excited synchronous machine 13.

[0038] Furthermore, the second axis 4 is advantageously also designed without a clutch. In particular, when the separately excited synchronous machine 13 is designed with an inductive current transformer, no drag torque losses occur.

[0039] By omitting a differential and the second output shaft, the second axle is particularly compact.

[0040] In Fig. 2 shows a separately excited synchronous machine 13. The Fig. The separately excited synchronous machine 13 shown in Figure 2 has a stator 16, a rotor 17 and a first part 18 of the stator 16, which radially encloses the rotor 17.

[0041] The rotor 17 rotates relative to the stator 16 during operation of the separately excited synchronous machine 13. In other words, the rotor 17 rotates about an axis parallel to the longitudinal direction X during operation of the separately excited synchronous machine 13.

[0042] The rotor 17 is arranged relative to the first part 18 of the stator 16 such that the first part 18 of the stator 16 inductively supplies the rotor 17 with excitation power by means of an alternating electromagnetic field during operation of the separately excited synchronous machine 13. The rotor 17 generates a static electromagnetic field relative to the rotor 17 through an excitation winding using the excitation power. The second part 18 of the stator 16 generates another alternating electromagnetic field. Through the interaction of the static electromagnetic field relative to the rotor 17 and the alternating electromagnetic field generated by the second part 18 of the stator 16, the rotor 17 rotates relative to the stator 16. The speed of the rotor 17 is adjusted by controlling the alternating electromagnetic field generated by the second part 18 of the stator 16. This will now be explained in more detail with reference to Fig. 3 are described.

[0043] Fig. 3 shows a schematic circuit of the separately excited synchronous machine 13. As in Fig. 3, the rotor 17 comprises a secondary winding 19 and an excitation winding 20. A rectifier 21 is provided between the secondary winding 19 and the excitation winding 20. The rectifier 21 is electrically connected to both the secondary winding 19 and the excitation winding 20. The rectifier 21 is designed to convert an alternating voltage received from the secondary winding 19 into a direct voltage. This direct voltage is output to the excitation winding 20. The alternating voltage is generated by an alternating electromagnetic field generated by the first part 18 of the stator 16 by means of induction in the secondary winding 19 of the rotor 17. This is then an inductive transformer.

[0044] The rotor 17 further comprises a secondary transceiver 22, which is electrically connected to the secondary winding 19. The secondary transceiver 22 has a further rectifier (not shown) for converting the alternating voltage from the secondary winding 19 into a direct voltage. The secondary transceiver 22 is therefore also supplied with energy by the alternating electromagnetic field generated by the first part 18 of the stator 16. The secondary transceiver 22 is designed to send information to the first part 18 of the stator 16 by modulating the alternating electromagnetic field generated by the first part 18 of the stator 16. For this purpose, the secondary transceiver 22 has a transmitting unit 23. The secondary transceiver 22 is further designed to receive information modulated onto the alternating electromagnetic field generated by the first part 18 of the stator 16. For this purpose, the secondary transceiver 22 has a receiving unit 24.The secondary transceiver 22 is electrically connected to an output side of a sensor 25 of the rotor 17. The sensor 25 is a temperature, magnetic field, and speed sensor designed to detect the temperature, magnetic field strength, and speed of the rotor. The temperature, magnetic field strength, and speed detected by the sensor 25 are input from the sensor 25 to the secondary transceiver 22. The secondary transceiver 22 is designed to modulate the information received from the sensor 25 onto the alternating electromagnetic field such that this information is received by the first part 18 of the stator 16.

[0045] The first part 18 of the stator 16 has a primary winding 26, an inverter 28, and a primary transceiver 30 connected to a controller 32. The primary transceiver 30 is also electrically connected to the primary winding 26. Furthermore, the inverter 28 is electrically connected to a power source 34. The power source 34 is a DC voltage source. The DC voltage applied to the input side of the inverter 28 by the power source 34 is converted by the inverter 28 into an AC voltage. The AC voltage is output by the inverter 28 to the primary winding 26. The AC voltage applied to the primary winding 26 generates the alternating electromagnetic field in the primary winding 26.

[0046] The alternating electromagnetic field acts on the secondary winding 19. Thus, an alternating voltage is induced in the secondary winding 19 by induction. The primary winding 26 and the secondary winding 19 are accordingly part of the inductive current transformer. Furthermore, the information modulated by the secondary transceiver 22 of the rotor 17, which corresponds to the temperature, magnetic field strength, and rotational speed of the rotor 17, is received via the primary winding 26 and the primary transceiver 30. The primary transceiver 30 is accordingly designed to receive the information modulated by the rotor 17 onto the alternating electromagnetic field generated by the primary winding 26. For this purpose, the primary transceiver 30 has a receiving unit 36. The primary transceiver 30 is further designed to transmit information to the rotor 17 by modulating the alternating electromagnetic field generated by the primary winding 26.For this purpose, the primary transceiver 30 has a transmitting unit 38. The primary transceiver 30 also has an additional rectifier to convert the alternating voltage applied to the primary winding 26 into a direct voltage. This supplies the primary transceiver 30 with power.

[0047] Furthermore, the primary transceiver 30 is electrically connected to the controller 32. The controller 32 is configured to control the separately excited synchronous machine 13 based on the information transmitted by the primary transceiver 30.

[0048] A modified embodiment of the above embodiments will be described below. The description of the above embodiments also applies to the modified embodiment, except for the difference described below.

[0049] According to the embodiment described above, the primary transceiver 30 has a rectifier for converting the AC voltage applied to the primary winding 26 into a DC voltage. In the present modified embodiment, no such rectifier is provided. Instead, the primary transceiver 30 is powered by an external DC voltage source 40, which is indicated by a dashed line in Fig. 3 is supplied with energy. Reference symbol 1 motor vehicle 2 Drivetrain 3 first axis 4 second axis 5 axle drive 6 Drive device 7 permanent magnet synchronous machine 8 gearboxes 9 Output shaft 10 wheels 11 Axle drive 12 Drive device 13 separately excited synchronous machine 14 gearboxes 15 Output shaft 16 Stator 17 Rotor 18 first part 19 Secondary winding 20 Excitation winding 21 rectifiers 22 secondary transceivers 23 Transmitter unit 24 receiving unit 25 sensors 26 Primary winding 28 inverters 30 primary transceivers 32 Control 34 Energy source 36 Receiving unit 38 Transmitter unit 40 DC voltage source QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2022 003 151 B3

[0002]

Claims

[1] Drive train (2) for a motor vehicle (1) with a first axle (3) and a second axle (4), wherein the first axle (3) has an electric drive device as the drive device (6) and the second axle (4) has a separately excited synchronous machine (13) as the drive device (12), characterized by that the first axis (3) is designed without a coupling. [2] Drive train according to claim 1, characterized by that the first axis (3) has a permanent magnet synchronous machine (7) as drive device (6). [3] Drive train according to claim 1, characterized by that the first axis (3) has a separately excited synchronous machine (13) as a drive device. [4] Drive train according to one of the preceding claims, characterized by that the separately excited synchronous machine (13) of the second axis (4) and / or the first axis (3) has an inductive transformer (19, 26) for current transmission. [5] Drive train according to one of the preceding claims, characterized by that the drive device (6) of the first axis (3) is arranged parallel to the axis. [6] Drive train according to one of the preceding claims, characterized by that the drive device (12) of the second axis (4) is arranged parallel to the axis. [7] Drive train according to one of the preceding claims, characterized by that the drive device (6) of the first axis (3) has a greater peak power and / or continuous power than the separately excited synchronous machine (13) of the second axis (4). [8] Drive train according to one of the preceding claims, characterized by that the first axle (3) is arranged as the front axle. [9] Drive train according to one of the preceding claims, characterized by that the separately excited synchronous machine (13) of the second axis (4) and / or the first axis (3) operates at a continuous speed of over 10000 min -1 is operable. [10] Motor vehicle (1) with a drive train (2), characterized by that the drive train (2) is designed according to one of the preceding claims.

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