DRIVE ASSEMBLY

Description

State of the art

[0001] The invention relates to a drive arrangement according to the preamble of claim 1.

[0002] Drive arrangements in which an electric machine is coupled to a planetary gearbox are known from the prior art. It is also known to implement electric drives as electric axles or as wheel hub drives.

[0003] DE 10 2015 207 074 B4 discloses a drive device for a vehicle, comprising a wheel carrier, a vehicle wheel, a damper, an electric motor, and a vehicle transmission designed as a two-stage planetary gearbox. The electric motor extends along the damper and is coupled to the input shaft of the vehicle transmission by means of a bevel gear. This drive device requires a large installation space.

[0004] A generic drive arrangement is known from DE 10 2017 006 266 A1. Further drive arrangements are known from DE 10 2019 212 556 B3 and DE 10 2015 207 074 B4. Disclosure of the invention

[0005] The problem underlying the invention is solved by a drive arrangement having the features of claim 1. Advantageous embodiments of the invention are described in the dependent claims.

[0006] According to the invention, a drive arrangement, particularly for a vehicle, is proposed, comprising an electric motor, a transmission, and an output shaft. The transmission has a first planetary stage (first planetary gear set) and a second planetary stage (second planetary gear set). The electric motor is coupled to a drive shaft so that the electric motor can drive the drive shaft (rotating it). The drive shaft is non-rotatably connected to a sun gear of the first planetary stage. A ring gear of the first planetary stage, which is coupled to the sun gear of the first planetary stage, particularly via planet gears of the first stage, is non-rotatably connected to a sun gear of the second planetary stage by means of an intermediate shaft. A ring gear of the second planetary stage, which is coupled to the sun gear of the second planetary stage, particularly via planet gears of the second stage, is non-rotatably connected to the output shaft.The sun gear of the first planetary stage is coupled to the ring gear of the first planetary stage by means of planet gears of the first planetary stage, wherein the planet gears of the first planetary stage are rotatably mounted on a section of the output shaft, in particular on the cup-shaped section of the output shaft, wherein the output shaft is coupled to a differential gear, in particular a bevel gear differential or a spur gear differential, so that the output shaft can drive the differential gear, in particular its differential carrier or rotary wheel carrier, and wherein the differential gear has two output shafts. According to the invention, the drive shaft is designed as a hollow shaft and one of the output shafts extends, in particular coaxially, through the drive shaft. This facilitates a compact design in the radial direction. Thus, the drive arrangement can be designed, in particular, as a coaxial electric axle.

[0007] The proposed drive arrangement allows for the necessary gear ratio for an electric drive to be implemented in an extremely compact design using a gearbox (planetary coupling gearbox). Thanks to its particularly compact radial design, vehicles equipped with such a drive arrangement can achieve a comparatively high ground clearance.

[0008] As already indicated, the drive arrangement is designed and / or intended for a vehicle. The vehicle can be a partially or fully electric vehicle (traction drive), e.g., a passenger car. Regardless of the vehicle type, the drive shaft can be the rotor shaft of the electric machine or a separate shaft that is rotationally fixed to the rotor shaft. The electric machine can further include a stator and / or a housing.

[0009] According to a further development, the output shaft can be designed, at least in sections, as a hollow shaft and arranged such that it surrounds the first planetary stage, the intermediate shaft, and / or the second planetary stage radially. This contributes to a comparatively compact design. The output shaft can have a hollow cylindrical or annular section (cross-section or inner and / or outer diameter constant), a shell-shaped section (cross-section tapering), and an output section (e.g., designed as a solid shaft). At the end facing the electric machine, the output shaft can be rotationally fixed to the ring gear of the second planetary stage.

[0010] According to a further development, the sun gear of the second planetary stage can be coupled to the ring gear of the second planetary stage by means of planet gears of the second planetary stage, wherein the planet gears of the second planetary stage are rotatably mounted on a housing section of the electric machine. This also contributes to a compact design of the drive arrangement with comparatively few components. In particular, the planet gears can each be rotatably mounted on the housing section of the electric machine by means of a planet gear pivot shaft that is attached to the housing section of the electric machine.

[0011] According to a further development, the first planetary stage can be arranged on an (axial) side of the gearbox facing away from the electric machine. This facilitates a comparatively simple implementation of supporting or bearing the planet gears of the second planetary stage on a housing section of the electric machine.

[0012] According to a further development, the gearbox can be configured such that, when driven by the electric machine (drive operating state of the drive arrangement), a portion of the torque transmitted from the electric machine to the gearbox is transferred to the output shaft via the planet gears of the first planetary stage, and another portion is transferred to the output shaft via the ring gear of the first planetary stage, the intermediate shaft, and the second planetary stage. In this way, a torque and power split is achieved. Thus, the gearbox components (planetary coupling gearbox), i.e., the components of the planetary gear stages, are subjected to lower loads in the drive operating state than in conventional planetary coupling gearboxes and can therefore be designed to be more compact, lighter, and more cost-effective.

[0013] According to a further development, the transmission can be configured such that, when the transmission is driven by the output shaft (recuperation operating state of the drive arrangement), a portion of the torque transmitted from the output shaft to the transmission is transferred to the input shaft via the planet gears of the first planetary stage, and another portion of the torque transmitted from the output shaft to the transmission is transferred to the input shaft via the second planetary stage, the intermediate shaft, and the ring gear of the first planetary stage. Thus, components of the transmission (planetary coupling transmission), i.e., the components of the planetary gear stages, are subjected to lower loads in the recuperation operating state than in conventional planetary coupling transmissions and can therefore be designed to be more compact, lighter, and more cost-effective.

[0014] According to a further development, the output shaft can be coupled, preferably directly, to a wheel hub drive, so that the output shaft can drive a wheel hub of the wheel hub drive. Thus, the output shaft (located on the outer diameter) can be used simply and directly as a drive in wheel hub drives. In other words, the drive arrangement can be designed as a wheel hub drive.

[0015] Possible embodiments of the invention are explained below with reference to the accompanying drawings. These show, schematically, Fig. 1 shows a sectional view of a drive arrangement; Fig. 2 shows a possible sectional view of the drive arrangement; and Fig. 3 shows a flow diagram of the power flow of the drive arrangement.

[0016] A drive arrangement contributes to Figure 1The entire assembly is designated by reference numeral 10. The drive arrangement 10 comprises an electric machine 12, a gearbox 14, and an output shaft 50. The gearbox 14 has a first planetary stage 20 (first planetary gear 20) and a second planetary stage 40 (second planetary gear 40).

[0017] The electric machine 12 is coupled to a drive shaft 16, so that the electric machine 12 can drive the drive shaft 16 in a rotating manner. The drive shaft 16 is non-rotatably connected to a sun gear 22 of the first planetary stage 20. A ring gear 28 of the first planetary stage 20, which is coupled to the sun gear 22 of the first planetary stage 20, is non-rotatably connected to a sun gear 42 of the second planetary stage 40 by means of an intermediate shaft 30. A ring gear 48 of the second planetary stage 40, which is coupled to the sun gear 42 of the second planetary stage 40, is non-rotatably connected to the output shaft 50.

[0018] The drive shaft 16 can be the rotor shaft of the electric machine 12 or a separate shaft that is rotationally fixed to the rotor shaft. The electric machine 12 can further comprise a stator and / or a housing (not shown).

[0019] In this example, the output shaft 50 is designed as a hollow shaft in sections and arranged such that it radially surrounds the first planetary stage 20, the intermediate shaft 30, and the second planetary stage 40. The hollow shaft 50 has a hollow cylindrical or annular section 52 (cross-section or inner and / or outer diameter constant), a shell-shaped section 54 (cross-section tapering), and an output section 56 (e.g., designed as a solid shaft). At the end facing the electric machine 12, the output shaft 50, or rather its section 52, is rotationally fixed to the ring gear 48 of the second planetary stage 40.

[0020] The sun gear 22 of the first planetary stage 20 is coupled to the ring gear 28 by means of planet gears 24. The planet gears 24 are rotatably mounted on a section of the output shaft 50, in this example on the cup-shaped section 54 of the output shaft 50. Each planet gear 24 is rotatably mounted on the output shaft 50 by means of a planet gear pivot 26, which is attached to the cup-shaped section 54 of the output shaft 50.

[0021] The sun gear 42 of the second planetary stage 40 is coupled to the ring gear 48 by means of planet gears 44. The planet gears 44 are rotatably mounted on a housing section 18 of the electric machine 12. Each planet gear 44 is rotatably mounted on the housing section 18 of the electric machine 12 by means of a planet gear pivot 46, which is attached to the housing section 18 of the electric machine 12. In this example, the first planetary stage 20 is arranged on an (axial) side 15 of the gearbox 14 that faces away from the electric machine 12.

[0022] This design allows for power splitting, as discussed below with reference to Fig.3 explained.

[0023] In this example, the output shaft 50, or rather its output section 56, is directly coupled to a wheel hub drive (not shown), so that the output shaft 50 can drive a wheel hub of the wheel hub drive. Thus, the drive arrangement 10 can be designed as a wheel hub drive.

[0024] In this example, the drive shaft 16 is designed as a solid shaft. The output section 56 of the output shaft 50 is also designed as a solid shaft. The central longitudinal axes of the drive shaft 16 and the output section 56 can be oriented parallel or coaxially to each other.

[0025] Figure 2 Figure 1 shows one possible design of the drive arrangement 10, wherein identical or functionally identical elements are provided with identical reference numerals and, to avoid repetition, reference is first made to the preceding explanations.

[0026] In contrast, the drive arrangement 10 has a drive shaft 16 which is designed as a hollow shaft. The output shaft 50 is coupled, in particular at its output section 56, to a differential gear 60, so that the output shaft 60 can drive the differential gear 60, in particular its differential body or planetary gear carrier (not shown).

[0027] The differential gear 60 can be configured as a bevel gear differential or as a spur gear differential. The differential gear 60 has two output shafts 62, 64, of which output shaft 62 extends, in particular coaxially, through the input shaft 16. Thus, the drive arrangement 10 can be configured as an electric axle (E-axle).

[0028] Figure 3 illustrates the torque and power flow of the drive arrangement 10 in a half-section (applies to both versions described above).

[0029] This shows Figure 3The power flow is shown for the case where the electric machine 12 drives the gearbox 14, i.e., the electric machine 12 transmits a torque to the gearbox 14 and the output shaft 50 via the input shaft 16 (drive operating state of the drive arrangement 10). The power flow is illustrated by arrows, where the percentages shown are chosen as examples and depend on the gearbox design (other percentages are conceivable).

[0030] In the example, the gearbox 14 is arranged such that when the gearbox 14 is driven by the electric machine 12 (drive operating state of the drive arrangement 10), a part T 1 of the torque transmitted from the electric machine 12 to the gearbox 14 is transmitted to the output shaft 50 or its shell-shaped section 54 by means of the planet gears 24 of the first planetary stage 20, and that a further part T 2 of the torque transmitted from the electric machine 12 to the gearbox is transmitted to the output shaft 50 or its hollow cylindrical section 52 via the ring gear 28 of the first planetary stage 20, the intermediate shaft 30 and the second planetary stage 40.

[0031] In this way, a torque or power split is achieved. Thus, components of the gearbox 14 (planetary coupling gearbox), i.e., the components of the planetary gear stages 20 and 40, are subjected to lower loads during drive operation than in conventional planetary coupling gearboxes and can therefore be designed to be more compact, lighter, and more cost-effective, as explained above.

[0032] As previously explained, in Figure 3 The arrows represent the power flow in the drive operating state of the drive arrangement 10. In the case that the output shaft 50 drives the gearbox 14 during recuperation (recuperation operating state of the drive arrangement 10), the power flow corresponds to the reverse direction of the arrows. Thus, power splitting can also occur in the recuperation operating state, as explained above.

[0033] The overall gear ratio can be calculated as follows, depending on the standard gear ratios of the individual planetary gear sets: i ges = 1 − i OI ⋅ 1 i OII − 1 1 i OII where in the morning the complete translation, in OI the standard translation of the first planetary stage and in OII The standard translation of the second planetary stage is.

Claims

1. Drive arrangement (10), in particular for a vehicle, having an electric machine (12), having a transmission (14) and having an output shaft (50), wherein the transmission (14) has a first planetary stage (20) and a second planetary stage (40), wherein the electric machine (12) is coupled to a drive shaft (16) so that the electric machine (12) can drive the drive shaft (16), wherein the drive shaft (16) is connected rotationally conjointly to a sun gear (22) of the first planetary stage (20), wherein a ring gear (28) of the first planetary stage (20), which is coupled to the sun gear (22) of the first planetary stage (20), is connected rotationally conjointly to a sun gear (42) of the second planetary stage (40) by means of an intermediate shaft (30), and wherein a ring gear (48) of the second planetary stage (40), which is coupled to the sun gear (42) of the second planetary stage (40), is connected rotationally conjointly to the output shaft (50), wherein the sun gear (22) of the first planetary stage (20) is coupled to the ring gear (28) of the first planetary stage (20) by means of planet gears (24) of the first planetary stage (20), wherein the planet gears (24) of the first planetary stage (24) are mounted rotatably on a section (56) of the output shaft (50), wherein the output shaft (50) is coupled to a differential transmission (60) so that the output shaft (50) can drive the differential transmission (60), and wherein the differential transmission (60) has two output shafts (62, 64), characterized in that the drive shaft (16) is designed as a hollow shaft and one of the output shafts (62) extends through the drive shaft (16).

2. Drive arrangement (10) according to Claim 1, characterized in that the output shaft (50) is designed at least sectionally as a hollow shaft and is arranged in such a way that it outwardly surrounds the first planetary stage (20), the intermediate shaft (30) and / or the second planetary stage (40).

3. Drive arrangement (10) according to either of the preceding claims, characterized in that the sun gear (42) of the second planetary stage (40) is coupled to the ring gear (48) of the second planetary stage (40) by means of planet gears (44) of the second planetary stage (40), wherein the planet gears (44) of the second planetary stage (40) are mounted rotatably on a housing section (18) of the electric machine (12).

4. Drive arrangement (10) according to one of the preceding claims, characterized in that the first planetary stage (20) is arranged on a side (15) of the transmission (14) that is relatively remote from the electric machine (12).

5. Drive arrangement (10) according to one of Claims 1 to 4, characterized in that the transmission (14) is configured in such a way that, in the case of the transmission (14) being driven by the electric machine (12), a part (T1) of the torque transmitted from the electric machine (12) to the transmission (14) is transmitted to the output shaft (50) by means of the planet gears (24) of the first planetary stage (20), and a further part (T2) of the torque transmitted from the electric machine (12) to the transmission (14) is transmitted to the output shaft (50) via the ring gear (28) of the first planetary stage (20), the intermediate shaft (30) and the second planetary stage (40).

6. Drive arrangement (10) according to one of Claims 1 to 5, characterized in that the transmission (14) is configured in such a way that, in the case of the transmission (14) being driven by the output shaft (50), a part of the torque transmitted from the output shaft (50) to the transmission (14) is transmitted to the drive shaft (16) by means of the planet gears (24) of the first planetary stage (20), and a further part of the torque transmitted from the output shaft (50) to the transmission (14) is transmitted to the drive shaft (16) via the second planetary stage (40), the intermediate shaft (30) and the ring gear (28) of the first planetary stage (20).

7. Drive arrangement (10) according to one of the preceding claims, characterized in that the output shaft (50) is coupled to a wheel-hub drive so that the output shaft (50) can drive a wheel hub of the wheel-hub drive.