Power device for a motor vehicle

Abstract

The invention relates to a drive unit (1) for a motor vehicle, comprising a traction motor (2), a torque converter (3), a variable transmission (4) and a differential transmission (5), the traction motor (2) being drivingly coupled to the differential transmission (5) in a given sequence via the torque converter (3) and the variable transmission (4). According to the invention, the traction motor (2) is drivingly coupled to the torque converter (3) via a spur gear transmission (20) or without a transmission.

Description

Technical Field

[0001] The invention relates to a drive unit for a motor vehicle, comprising a traction motor, a torque converter, a transmission and a differential gear, wherein the traction motor is drive-coupled to the differential gear in a given sequence via the torque converter and the transmission. Background Art

[0002] For example, the document DE 10 2015 215 965 A1 is known from the prior art. This document describes a drive unit for a motor vehicle having at least one traction motor for driving the motor vehicle and a hydrodynamic torque converter drivable by the traction motor, wherein a transmission mechanism drivable by the traction motor is provided, via which the torque converter can be driven. Summary of the Invention

[0003] The object of the present invention is to provide a drive unit for a motor vehicle which has advantages over known drives, in particular is that it can be operated flexibly and can be realized in a small installation space.

[0004] According to the invention, this is achieved by a drive unit for a motor vehicle having the features of claim 1. Provision is made here for the traction motor to be drive-coupled to the torque converter via a spur gear mechanism or without a gear mechanism.

[0005] Advantageous embodiments of the invention with suitable improvements are given in the dependent claims. It should be pointed out that the embodiments explained in the description are non-limiting; on the contrary, any variation of the features disclosed in the description, claims and drawings is possible.

[0006] The power unit is used to drive the motor vehicle, i.e., to provide a driving torque intended to drive the motor vehicle. To provide the driving torque, the power unit includes a traction motor, and the driving torque is provided at least temporarily or continuously entirely by means of the traction motor. The motor vehicle is preferably an electric vehicle or an electrically driven motor vehicle and preferably does not have an internal combustion engine.

[0007] In addition to the traction motor, the power unit also includes a torque converter, a transmission mechanism, and a differential mechanism. The torque converter is drive-wisely arranged between the traction motor and the transmission mechanism, so that the transmission mechanism is drive-wisely coupled to the traction motor via the torque converter. The differential mechanism is in turn connected to the torque converter via the transmission mechanism; accordingly, the transmission mechanism is drive-wisely located between the torque converter and the differential mechanism. Overall, the traction motor is drive-wisely connected to the differential mechanism via the torque converter and the transmission mechanism, with the torque converter and the transmission mechanism being drive-wisely arranged in a given order.

[0008] A transmission is understood to be a transmission that produces a transmission ratio other than 1. In this context, a speed ratio other than 1 always exists between the transmission output shaft and the transmission input shaft of the transmission—at a speed other than zero.

[0009] Preferably, the differential drive mechanism is an axle differential drive mechanism. This means that exactly one wheel axle of the motor vehicle is connected to the drive unit via a differential drive mechanism. The wheel axle has multiple sub-shafts, which are coupled to each other via a differential drive mechanism and are each connected to the drive unit via a differential drive mechanism. Alternatively, the differential drive mechanism can be a central differential drive mechanism. In this case, multiple wheel axles are connected to the drive unit or the traction motor via differential drives. For example, each of the multiple wheel axles is connected to a differential drive mechanism of the drive unit via an axle differential drive mechanism, resulting in a total of multiple differential drives.

[0010] In some cases, motor vehicles require very high or extremely high drive torques. This is particularly true for off-road vehicles. It is possible to design the traction motor accordingly and set a corresponding rated torque. However, this results in a large traction motor and, accordingly, a large space requirement for the power unit. The same applies to the provision of multiple traction motors connected to one another in terms of drive technology, where multiple traction motors drive the same axle of the vehicle. A shiftable transmission or a gearbox can also be provided to meet these high torque requirements. However, this results in a high complexity of the power unit and a large space requirement.

[0011] For this reason, the power unit includes a torque converter. The torque converter at least temporarily increases torque, providing a greater drive torque at the vehicle's wheel axle than would be achievable at the axle's current speed and if the axle were coupled to the power unit without a torque converter. Thus, the torque converter not only provides, at least temporarily, a very high drive torque, but also enables particularly agile handling at low speeds. This is particularly important, for example, when starting a vehicle off-road and negotiating obstacles. In principle, the wheel axle speed can be adjusted more sensitively. Furthermore, overload decoupling is achieved, or at least can be achieved, between the traction motor and the wheel axle.

[0012] For example, it is known to connect the traction motor to the torque converter via a planetary gear mechanism. However, this requires a relatively large amount of space, especially since the traction motor must always be mounted coaxially with the planetary gear mechanism, and there are no other options for the traction motor's arrangement. For this reason, according to the present invention, the traction motor should be connected to the torque converter via a spur gear mechanism or without a gear mechanism. Spur gear mechanisms are distinguished by the fact that the gears are on parallel axes, i.e., the gears have axes of rotation that are spaced apart and parallel to one another. This differs from planetary gear mechanisms, in which the sun gear, planet carrier, and ring gear are arranged coaxially with one another.

[0013] Alternatively, the traction motor is connected to the torque converter in a gearless manner, that is, without an intermediate connecting gear. This means that the drive shaft of the traction motor is coupled to the input shaft of the torque converter in such a way that they always have the same rotational speed. On the one hand, the described design of the power unit enables the aforementioned flexible operation, and on the other hand, it offers an extremely compact design and great flexibility in the arrangement of the traction motor.

[0014] A refinement of the present invention provides that the speed change transmission is designed as a planetary gear transmission, a single-stage or multi-stage spur gear transmission, or a belt transmission. In other words, the speed change transmission is a planetary gear transmission, a spur gear transmission, or a belt transmission. The planetary gear transmission comprises a sun gear, a ring gear, and a planetary gear carrier, wherein at least one planet gear is rotatably supported on the planetary gear carrier. At least one planet gear engages with both the sun gear and the ring gear, i.e., meshes with them. Of course, preferably, multiple planet gears are rotatably supported on the planetary gear carrier, wherein each of the planet gears meshes with both the sun gear and the ring gear. The planetary gear transmission can achieve particularly high transmission ratios.

[0015] Alternatively, the speed change mechanism is designed as a single-stage or multi-stage spur gear transmission. This means that the speed change mechanism has two gears in the first variant and at least three gears in the second variant, with the input gear being drive-connected to the output gear only via at least one intermediate gear. If multiple intermediate gears are present, they are connected in series for drive-related purposes. In another embodiment, the speed change mechanism is a belt drive, in which the drive torque is transmitted using a traction device. Depending on the design of the speed change mechanism, either the power unit can be arranged flexibly and with minimal space requirements, or a relatively high transmission ratio can be achieved.

[0016] One refinement of the present invention provides for a torque converter having a pump wheel located on the traction motor side in terms of drive technology, a turbine wheel located on the differential gear side in terms of drive technology, and a stator wheel, wherein the stator wheel is arranged on a stator shaft. This design of a torque converter is generally known. The pump wheel is connected to the traction motor in terms of drive technology, either via a spur gear mechanism or without a gear mechanism. In contrast, the turbine wheel is connected to the differential gear mechanism in terms of drive technology and is connected to the traction motor solely via the pump wheel.

[0017] The pump impeller pumps fluid toward the turbine, driving the turbine. The pump impeller and turbine are fluidically or hydraulically connected via the fluid. A stator is fluidically arranged between the pump impeller and the turbine, guiding the fluid flow-wise. The stator is arranged on a stator shaft, for example, rigidly connected to the stator shaft.

[0018] It can be provided that the stator can rotate in one direction of rotation by means of a freewheel, but is fixed in the opposite direction of rotation. Accordingly, the torque converter is designed as a Trilok torque converter. For example, the freewheel is located between the stator and the stator shaft, with the stator shaft being arranged rigidly. However, it can also be provided that the stator is rigidly coupled to the stator shaft, and the stator shaft is mounted so that it can rotate in only one direction of rotation by means of the freewheel. This design of the torque converter can achieve a particularly significant increase in torque.

[0019] One refinement of the present invention provides that the stator shaft is received by the hollow input shaft, or that the stator shaft is hollow and receives the output shaft, located between the torque converter and the transmission, or the differential output shaft of the differential transmission. In the first case, the stator shaft is arranged coaxially with the input shaft, and in the latter case, the stator shaft is arranged coaxially with the output shaft or the differential output shaft. This enables a compact design of the power unit.

[0020] One refinement of the present invention provides for the traction motor to be arranged coaxially with the output shaft or eccentrically relative to the output shaft. In particular, a coaxial arrangement of the traction motor exists when the traction motor is coupled to the torque converter without a gear mechanism. The eccentric arrangement is achieved with the aid of a spur gear mechanism. This, in turn, contributes to a particularly compact drive unit.

[0021] One refinement of the present invention provides that a lockup clutch is arranged, viewed in the axial direction relative to the traction motor's axis of rotation, between the traction motor and the torque converter or on the side of the torque converter facing away from the traction motor. The axis of rotation of the traction motor is understood to be the axis of rotation of the output shaft or the crankshaft of the traction motor, which is connected to the torque converter via a spur gear mechanism or without a gear mechanism. The described options for arranging the lockup clutch further ensure a space-saving design of the drive unit.

[0022] One refinement of the present invention provides that, viewed in the axial direction with respect to the rotational axis of the traction motor, the turbine wheel is arranged on the side of the pump wheel facing the traction motor, or, viewed in the axial direction with respect to the rotational axis of the traction motor, the pump wheel is arranged on the side of the turbine wheel facing the traction motor. These different arrangements of the turbine wheel or pump wheel further contribute to a compact design of the power unit, thereby minimizing the installation space requirement.

[0023] A refinement of the present invention provides for a planetary gear train comprising a sun gear, a ring gear, and at least one planet gear rotatably supported on a planet gear carrier and engaged with the sun gear and the ring gear. The sun gear is drive-wise arranged on the torque converter side, the planet gear carrier is drive-wise arranged on the transmission side, and the ring gear is stationary. This should be understood as meaning that the sun gear is drive-wise coupled to the torque converter, while the planet gear carrier is coupled to the torque converter solely via the sun gear. Conversely, the planet gear carrier is coupled to the transmission, while the sun gear is coupled to the transmission solely via the planet gear carrier. The ring gear is arranged in a fixed position, for example, fastened to the transmission housing or formed integrally therewith. This achieves a compact design of the power unit.

[0024] A refinement of the present invention provides that the ring gear is secured via a ring gear shaft that is arranged so as to overlap the traction motor in the axial direction relative to the traction motor's axis of rotation. The ring gear is secured by means of the ring gear shaft, which is rigidly connected to the ring gear. The ring gear shaft extends from the ring gear in the axial direction relative to the traction motor's axis of rotation far enough that it overlaps the traction motor or even completely bridges or passes through it. This ensures a secure securement of the ring gear.

[0025] A further development of the invention provides that the ring gear shaft is arranged coaxially with the differential gear output shaft and / or the stator shaft. A coaxial arrangement enables a particularly compact design of the drive unit.

[0026] The features and feature combinations described in the specification, in particular the features and feature combinations described in the following description of the figures and / or shown in the figures, can be used not only in the combination indicated, but also in other combinations or individually, without departing from the scope of the present invention. Therefore, embodiments that are not explicitly shown or explained in the specification and / or the figures but can be derived or inferred from the explained embodiments are also considered to be included in the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The invention is explained below on the basis of initial examples shown in the accompanying drawings without limiting the invention.

[0028] in:

[0029] Figure 1 A schematic diagram showing a power plant for a motor vehicle according to a first embodiment is shown,

[0030] Figure 2 shows a schematic diagram of a power plant of a second embodiment,

[0031] Figure 3 shows a schematic diagram of a third embodiment of a power plant,

[0032] Figure 4 shows a schematic diagram of a power plant of a fourth embodiment,

[0033] Figure 5 A schematic diagram shows a power plant according to a fifth embodiment, and

[0034] Figure 6 A sixth embodiment of a power plant is shown schematically. DETAILED DESCRIPTION

[0035] Figure 1 A schematic diagram of a drive unit 1 for a motor vehicle in a first embodiment is shown. The drive unit 1 comprises a traction motor 2, a torque converter 3, a speed change mechanism 4, and a differential mechanism 5. The traction motor 2 has a drive shaft 6, which is coupled to the torque converter 3 in terms of drive technology. In the embodiment shown here, the drive shaft 6 is coupled to the torque converter 3 without a gear mechanism, i.e., without a gear mechanism. The drive shaft 6 is coupled to the pump impeller 7, preferably rigidly and permanently. In addition to the pump impeller 7, the torque converter 3 also has a vortex impeller 8 and a stator 9. The stator 9 is arranged fluidically between the pump impeller 7 and the turbine wheel 8 and is rotatably supported on a stator shaft 11 via a freewheel 10. The stator shaft 11 is fixed in position, for example, to a housing 12 of the drive unit 1, which is only indicated here.

[0036] The torque converter 3 also has a lockup clutch 13, by means of which the pump impeller 7 and the turbine 8 can be mechanically coupled. Thus, in a first position of the lockup clutch 13, the pump impeller 7 and the turbine 8 are decoupled from each other in terms of drive technology. In contrast, in a second position, the pump impeller and the turbine 8 are mechanically connected to each other, preferably rigidly or at least substantially rigidly, i.e., mechanically connected with substantially no clutch slip. The drive shaft 6 is connected to the pump impeller 7 via an input shaft 14 of the torque converter 3.

[0037] The turbine 8 is connected to the transmission 4 via an output shaft 15. In the embodiment shown here, the transmission is designed as a multi-stage spur gear. The output shaft 15 is coupled via the transmission 4 to the differential 5, specifically to its input gear 16. The transmission 4 is drive-connected via the differential 5 to a wheel axle 17 of the motor vehicle, which has two partial shafts 18 and 19. These partial shafts 18 and 19 can also be referred to as differential output shafts.

[0038] It can be seen that the stator shaft 11 is designed as a hollow shaft and accommodates the output shaft 15 therein. In addition, the traction motor 2 is arranged coaxially with the output shaft 15 due to its transmission-free connection to the torque converter 3. The lockup clutch 13 is arranged between the traction motor 2 and the torque converter 3 in the axial direction relative to the rotation axis of the traction motor 2 or the drive shaft 6, that is, on the side of the torque converter 3 facing away from the speed change mechanism 4. Viewed again in the axial direction, the turbine 8 is located on the side of the pump wheel 7 facing the traction motor 2. This achieves a compact design of the power unit 1 as a whole. In addition, as an alternative to the design shown here, the speed change mechanism 4 can also be implemented as a belt drive.

[0039] Figure 2 A schematic diagram shows a second embodiment of a drive unit 1. For the names and basic design of the individual components, reference is made to the description of the first embodiment, and only the differences are explained below. The difference lies in the fact that the traction motor 2 is connected to the torque converter 3 or the pump wheel 7 via a spur gear mechanism 20 for drive technology. This results in an eccentric arrangement of the traction motor 2 relative to the output shaft 15.

[0040] The input shaft 14 or the pump wheel 7 is connected to the lockup clutch 13 via a coupling shaft 21. The coupling shaft 21 bridges the turbine wheel 8 in the axial direction, so that the turbine wheel 8 is located or accommodated between the pump wheel 7 on the one hand and the lockup clutch 13 on the other hand. In this case, the speed change transmission 4 is a single-stage spur gear transmission. The stator shaft 11 is arranged coaxially with the output shaft 15 and is partially accommodated by the input shaft 14, which is designed as a hollow shaft. The stator shaft 11 extends axially from the stator 9 or freewheel 10 in the direction of the traction motor 2. In particular, the stator shaft is connected to the housing 12 on the side of the spur gear transmission 20 facing away from the stator 9. The lockup clutch 13 is arranged axially on the side of the torque converter 3 facing away from the traction motor 2. Viewed in the axial direction, the turbine wheel 8 is located on the side of the pump wheel 7 facing away from the traction motor 2.

[0041] As an alternative to the illustration shown, the traction motor 2 can also be arranged on the opposite side, ie so that the spur gear transmission 20 is connected to the pump wheel 7 via the coupling shaft 21. Of course, the speed change transmission 4 can also be a belt transmission instead of a spur gear transmission.

[0042] Figure 3 A third design of the power unit 1 is again shown schematically. Reference is once again made to the above explanations and only the differences are explained. In the third embodiment, the traction motor 2 is connected to the torque converter 3 via a spur gear mechanism 20. The speed change mechanism 4 is designed as a single-stage spur gear mechanism. The difference from the second embodiment lies in particular in the mirror-image arrangement of the pump wheel 7 and the turbine wheel 8 and the resulting arrangement of the stator shaft 11. The stator shaft is arranged coaxially with the output shaft 15 and is designed as a hollow shaft for receiving the output shaft 15. As an alternative to the embodiment shown, the traction motor 2 can be arranged on the other side of the torque converter 3, i.e. on the side of the pump wheel 7 opposite the turbine wheel 8. In addition, the speed change mechanism 4 can be designed as a belt drive instead of a spur gear mechanism.

[0043] Figure 4 A schematic diagram of a fourth embodiment of the power unit 1 is shown. Reference is made to the above explanations, in particular to the explanations of the second embodiment, and only the differences are explained. The difference is that the speed change mechanism 4 is not designed as a spur gear mechanism, but as a planetary gear mechanism. Accordingly, the speed change mechanism has a sun gear 22, a ring gear 23 and a planetary gear carrier 24, on which planetary gears 25 are rotatably supported. The planetary gears 25 mesh not only with the sun gear 22, but also with the ring gear 23. The planetary gear carrier 24 is connected to the differential mechanism 5, in particular, the planetary gear carrier 24 replaces the input gear 16. The ring gear 23 is arranged in a fixed position and, for this purpose, is preferably connected to the housing 12.

[0044] The stator shaft 11 is designed as a hollow shaft and accommodates one of the partial shafts 18 and 19 therein, here for example the partial shaft 18. Accordingly, the input shaft 14 also surrounds the partial shaft 18. The same applies to the output shaft 15, which is also a hollow shaft and surrounds the partial shaft 18. In a modification of the illustrated design, the traction motor 2 can be arranged on the opposite side of the torque converter 3 and correspondingly connected to the pump wheel 7 via a coupling shaft 21.

[0045] Figure 5 A schematic diagram shows a fifth embodiment of a power plant 1. Reference is made to the above embodiments, particularly the explanation of the fourth embodiment, and only the differences are noted. The difference is that the traction motor 2 is arranged on the side of the turbine 8 facing away from the pump impeller 7 and is connected to the pump impeller 7 via a coupling shaft 21 spanning the turbine 8. The input shaft 14 is designed as a hollow shaft and surrounds the speed change mechanism 4, which is again a planetary gear mechanism.

[0046] In order to arrange the ring gear 23 in a fixed position, a ring gear shaft 26 rigidly connected to the ring gear 23 needs to extend from the input shaft 14 and be arranged accordingly on the side of the spur gear mechanism 20 opposite the speed change mechanism 4. The ring gear shaft 26 is fastened to the housing 12 on its side facing away from the ring gear 23. Preferably, this fastening overlaps with the traction motor 2 when viewed in the axial direction. As an alternative to the described design, the arrangement of the pump wheel 7 and the turbine wheel 8 can be interchanged, so that the pump wheel 7 is arranged on the side of the turbine wheel 8 facing the traction motor 2.

[0047] Figure 6 A schematic diagram of a sixth embodiment of the drive unit 1 is shown. Reference is made to the above explanations, especially those regarding the fifth embodiment. Only the differences are noted below. The difference is that the spur gear mechanism 20 is omitted, so that the traction motor 2 is connected to the torque converter 3 without a transmission mechanism. Here, the traction motor 2 is arranged coaxially with the wheel axle 17, in particular the split shaft 19, and surrounds the wheel axle. This requires extending the ring gear shaft 26 so that it passes through the traction motor 2 and is fastened to the housing 12 on the side of the traction motor 2 facing away from the transmission mechanism 4.

[0048] Alternatively, the traction motor 2 can be arranged in the axial direction between the torque converter 3 and the differential gear mechanism 5. It is also possible to arrange the traction motor 2 on the opposite side of the torque converter 3, so that the traction motor 2 is located on the side of the pump wheel 7 away from the turbine 8. In addition, in another design, another speed change gear mechanism can be present in each of the partial shafts 18 and 19, which is implemented as a spur gear mechanism or a planetary gear mechanism, for example.

[0049] List of Reference Numerals

[0050] 1 Power unit

[0051] 2 traction motor

[0052] 3 Torque converter

[0053] 4-speed transmission mechanism

[0054] 5 Differential transmission mechanism

[0055] 6 drive shafts

[0056] 7 pump wheel

[0057] 8 Turbine

[0058] 9 guide wheels

[0059] 10 Freewheel

[0060] 11 guide wheel shaft

[0061] 12 shell

[0062] 13 Lock-up clutch

[0063] 14 Input shaft

[0064] 15 output shaft

[0065] 16 input gears

[0066] 17 axles

[0067] 18-point axis

[0068] 19-axis

[0069] 20 spur gear transmission mechanism

[0070] 21 connecting shaft

[0071] 22 Sun gear

[0072] 23 ring gear

[0073] 24 planetary gear carrier

[0074] 25 planetary gears

[0075] 26 ring gear shaft

Claims

1. A power unit (1) for a motor vehicle, comprising a traction motor (2), a torque converter (3), a speed change transmission mechanism (4) and a differential transmission mechanism (5), wherein: The traction motor (2) is coupled to the differential gear (5) in a given sequence via a torque converter (3) and a speed change gear (4), wherein the traction motor (2) is coupled to the torque converter (3) in a drive-related manner via a spur gear gear (20) or without a gear.

2. The power device according to claim 1, characterized in that: The speed change transmission mechanism (4) is designed as a planetary gear transmission mechanism, a single-stage or multi-stage spur gear transmission mechanism, or a belt transmission mechanism.

3. The power plant according to any one of the preceding claims, characterized in that The torque converter (3) has a pump wheel (7) located on the traction motor (2) side in terms of drive technology, a turbine wheel (8) located on the differential gear (5) side in terms of drive technology, and a stator (9), wherein the stator (9) is arranged on a stator shaft (11).

4. The power plant according to any one of the preceding claims, characterized in that The stator shaft (11) is received by an input shaft (14) designed as a hollow shaft, or the stator shaft (11) is designed as a hollow shaft and receives an output shaft (15) located between the torque converter (3) and the transmission (4) in terms of drive technology or a differential transmission output shaft of the differential transmission (5).

5. The power plant according to any one of the preceding claims, characterized in that The traction motor (2) is arranged coaxially with the output shaft (15) or eccentrically with respect to the output shaft (15).

6. The power plant according to any one of the preceding claims, characterized in that Viewed in the axial direction based on the rotation axis of the traction motor (2), a lockup clutch (13) is arranged between the traction motor (2) and the torque converter (3) or on the side of the torque converter (3) away from the traction motor (2).

7. The power plant according to any one of the preceding claims, characterized in that When viewed in the axial direction with the rotation axis of the traction motor (2) as the reference, the turbine (8) is arranged on the side of the pump wheel (7) facing the traction motor (2), or when viewed in the axial direction with the rotation axis of the traction motor (2) as the reference, the pump wheel (7) is arranged on the side of the turbine (8) facing the traction motor (2).

8. The power plant according to any one of the preceding claims, characterized in that The planetary gear mechanism comprises a sun gear (22), a ring gear (23), and at least one planet gear (25) rotatably supported on a planet gear carrier (24) and engaged with the sun gear (23) and the ring gear (23), wherein the sun gear (22) is arranged on the torque converter (3) side in terms of drive technology, the planet gear carrier (24) is arranged on the speed change mechanism (4) side in terms of drive technology, and the ring gear (23) is fixed.

9. The power plant according to any one of the preceding claims, characterized in that The ring gear (23) is fixed by a ring gear shaft (26) which is arranged to overlap with the traction motor (2) in an axial direction based on the rotation axis of the traction motor (2).

10. The power plant according to any one of the preceding claims, characterized in that The ring gear shaft (26) is arranged coaxially with the differential transmission mechanism output shaft and / or the stator shaft (11).

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