DE102020211080A1 - Electric drive for a vehicle, drive train and method - Google Patents

Abstract

The invention relates to an electric drive for a vehicle, comprising: an electric machine (2), the rotor (2.1) of which is connected to an input shaft (11) of a first planetary gear set (7), an output shaft (12) arranged coaxially with the input shaft (11), and three shifting elements (3, 4, 5) for engaging gears, with planet wheels (7.3, 7.4) mounted on a planet wheel carrier (7.5) having two different effective diameters, a first sun wheel (7.1) of the planetary wheel set (7) with the larger one effective diameter (7.3) of the planetary gears is in meshing engagement, a second sun gear (7.2) of the planetary gearset (7) with the smaller effective diameter (7.4) of the planetary gears is in meshing engagement, a ring gear (7.6) of the planetary gearset (7) with the larger effective diameter (7.3 ) is in meshing engagement, the first sun gear (7.1) of the planetary gear set (7) being non-rotatably connected to the first input shaft (11), the second sun gear (7.2) of the planetary gear set zes (7) is non-rotatably connected to the output shaft (12), the three shifting elements being arranged and designed in such a way that by selectively locking two of the three shifting elements (3, 4, 5) three different gear stages (E1, E2, E3) to be provided.

Description

The invention relates to an electric drive for a vehicle, a drive train and a method.

the WO 2014/029650 relates to a drive unit for an electrically driven vehicle, with an electric machine and a transmission with a first planetary gear set having a first sun gear, at least one first planetary gear and a first ring gear, and a second planetary gear set having a second sun gear, at least one second planetary gear and a second ring gear Planetary gear set, wherein the first and the second sun gear are arranged coaxially and the first and second planetary gear are rotatably mounted on a common planetary carrier, and wherein the drive shaft of the electric machine is drive-connected to the first sun gear, and at least one ring gear can be held in place via a braking device. The second sun gear of the second planetary gear set is connected to an output shaft and at least a first planet gear of the first planetary gear set is rotatably connected to a second planet gear of the second planetary gear set.

The object of the present invention is to provide an alternative electric drive for a motor vehicle and an alternative drive train. In particular, an electric drive or a drive train is to be provided that is axially short. In addition, a method for switching the electric drive is to be provided. The object is solved by the features of the independent claims. Preferred embodiments emerge from the dependent claims.

According to the first aspect of the invention, an electric drive for a vehicle is provided. The electric drive comprises an electric machine, the rotor of which is connected to an input shaft of a first planetary gear set, an output shaft arranged coaxially with the input shaft, and three shifting elements for engaging gears. Planetary gears mounted on a planetary gear carrier have two different effective diameters. A first sun gear of the planetary gear set meshes with the larger effective diameter of the planetary gears. A second sun gear of the planetary gear set meshes with the smaller effective diameter of the planetary gears. A ring gear of the planetary gear set meshes with the larger effective diameter. The first sun gear of the planetary gear set is non-rotatably connected to the first input shaft. The second sun gear of the planetary gear set is non-rotatably connected to the output shaft. The three switching elements are arranged and designed in such a way that three different gear stages can be provided by selectively closing two of the three switching elements. The individual switching elements can be present both as a non-positive and as a form-fitting switching element. Force-locking or friction-locking shifting elements are, for example, multi-plate shifting elements, in particular in the form of multi-plate clutches. Positive shifting elements are, for example, claw shifting elements and cone shifting elements in the form of claw or cone clutches.

A first switching element is preferably designed to connect the planet carrier of the planetary gear set with a second switching element. A third shifting element is preferably designed to connect the ring gear to the second shifting element. The second switching element is preferably designed to fix the first switching element and the third switching element to a non-rotatable component. Fixing takes place in particular by non-rotatable connection with a non-rotatable component of the electric drive, which is preferably a permanently stationary component, preferably a housing of a transmission, a part of such a housing or a non-rotatable component connected thereto.

A respective non-rotatable connection of the rotatable components of the electric drive is preferably implemented according to the invention via one or more intermediate shafts, which can also be present as short intermediate pieces when the components are spatially close together. In concrete terms, the components that are permanently connected to one another in a rotationally fixed manner can each be present either as individual components that are connected to one another in a rotationally fixed manner or also in one piece. In the second-mentioned case, the respective components and the shaft that may be present are then formed by a common component, this being realized in particular when the respective components in the electric drive are spatially close to one another.

In the case of components of the electric drive which are connected to one another in a rotationally fixed manner only by actuation of a respective switching element, a connection is also preferably implemented via one or more intermediate shafts. The “connection” of the rotor of the electric machine to the input shaft is to be understood within the meaning of the invention as such a connection that there is a constant speed dependency between the rotor of the electric machine and the input shaft.

By selectively actuating the shift elements, three forward gears can be achieved, two of the three switching elements must be actuated to form the gears. A first gear can thus be achieved by engaging or actuating the first and third shifting element. A second gear can be achieved by closing the second and third shifting element. A third gear can be achieved by engaging the first and third shifting elements.

The electric drive enables an output that is axis-parallel to the input shafts or also coaxial. The transmission can therefore be used in particular for a front-transverse drive train of a motor vehicle. The electric drive according to the invention manages without a second ring gear, so that a three-speed electric drive can be provided that has few components.

The electric drive according to the invention manages without a second ring gear, which leads to a reduction in the number of parts. The planetary gear set can in particular be arranged radially inside the electric machine in order to provide an electric drive that is particularly short axially. In particular, the output shaft can be arranged inside the input shaft, which is designed as a hollow shape, and inside the planet gear carrier, which is designed as a hollow shape. However, the output shaft can also be arranged at an axial distance from the input shaft.

According to a second aspect of the invention, a powertrain for a vehicle is provided. The powertrain includes an electric drive according to the first aspect of the invention and a differential device connected to the output shaft of the first planetary gear set. The differential device can be formed in many ways. The individual advantages of the electric drive apply mutatis mutandis to the drive train.

Preferred is a drive train, wherein the differential device comprises a bevel gear differential and a transmission gear in the form of a second planetary gear set, wherein the sun gear of the second planetary gear set is connected to the second sun gear of the first planetary gear set, the planet gear carrier is connected to an input element of the bevel gear differential, the ring gear is connected to the non-rotatable component is fixed.

Alternatively, a drive train is preferred, wherein the differential device comprises a bevel gear differential and a transmission gear in the form of a single-stage spur gear stage with a first spur gear and a second spur gear, the first spur gear being non-rotatably connected to the second sun gear of the stepped planetary gear set and meshing with the second spur gear stands, the second spur gear is non-rotatably connected to an input element of the bevel gear differential.

Alternatively, a drive train is preferred, wherein the differential device comprises a bevel gear differential and a transmission gear in the form of a two-stage spur gear stage with a first spur gear, a second spur gear and a third spur gear, the first spur gear being non-rotatably connected to the second sun gear of the stepped planetary gear set and to the third spur gear is in meshing engagement, the third spur gear is non-rotatably connected to the second spur gear, and the second spur gear is non-rotatably connected to an input element of the bevel gear differential.

Alternatively, a drive train is preferred, wherein the differential device comprises a second planetary gear set and a third planetary gear set, the sun gear of the second planetary gear set being connected to the second sun gear of the first planetary gear set, the planetary gear carrier being connected to a first output shaft, the ring gear of the second planetary gear set being connected to it is connected to the sun gear of the third planetary gear set, the planet carrier is fixed to the non-rotatable component, the ring gear is connected to a second output shaft.

The drive trains mentioned above are particularly short axially if the first planetary gear set is arranged radially inside the rotor.

According to a third aspect of the invention, a method for shifting the electric drive and/or the drive train is provided according to one of the preceding claims, wherein in a first gear the first shifting element and the second shifting element are closed and the third shifting element is opened, wherein in a second Gear the second switching element and the third switching element are closed and the first switching element is opened, and wherein in a third gear the first switching element and the third switching element are closed and the second switching element is closed.

• 1-3 jeweils eine schematische Ansicht eines Kraftfahrzeugantriebsstrangs eines Fahrzeugs bei welchem das erfindungsgemäße Getriebe zur Anwendung kommt;
• 4 eine schematische Ansicht eines Elektroantriebs in einer bevorzugten Ausführungsform; und
• 5 eine Schaltmatrix des Elektroantriebs aus 4.

Advantageous embodiments of the invention, which are explained below, are shown in the drawings. It shows:

• 1-3 in each case a schematic view of a motor vehicle drive train of a vehicle in which the transmission according to the invention is used;
• 4 a schematic view of an electric drive in a preferred embodiment; and
• 5 a switching matrix of the electric drive 4 .

1 until 3 each show a schematic view of a motor vehicle drive train 100 of a vehicle 1000. The vehicle is a passenger car.

The powertrain 100 according to FIG 1 shows an electric drive that drives the front axle B of the vehicle 1000 . The drive train 100 includes a transmission 1 with a planetary gear set, not shown, which divides the drive torque of the electric machine 2 over two output shafts 9.11 and 9.12. The drive train 100 also includes a differential device, which has a bevel gear differential 9 and a transmission 14 in the form of a spur gear. The transmission 1 and electric machine 2 are arranged coaxially to an axis A. Axis A and axis B are arranged paraxially, so that there is an paraxial output. The forward direction of travel is represented by the arrow 99 . As also in 1 can be seen, the transmission 1 and the electric machine 2 are aligned transversely to the direction of travel 99 of the vehicle 1000 .

The powertrain 100 according to FIG 2 shows an electric drive that drives the front axle B of the vehicle 1000 . The drive train includes a transmission 1 with a planetary gear set, not shown, which divides the drive torque of the electric machine 2 over two output shafts 9.11 and 9.12. The drive train 100 also includes a differential device, which includes a planetary gear 8 and a bevel gear differential 9 . Transmission 1 and electric machine 2 are arranged coaxially to an axis A, which coincides with the drive axis B, so that there is a coaxial output. The forward direction of travel is represented by the arrow 99 . As also in 2 can be seen, the transmission 1 and the electric machine 2 are aligned transversely to the direction of travel 99 of the vehicle 1000 .

The powertrain 100 according to FIG 3 shows an electric drive that drives the front axle B of the vehicle 1000 . The drive train includes a transmission 1 with a planetary gear set, not shown, which divides the drive torque of the electric machine 2 over two output shafts 13.11 and 8.12. The drive train 100 also includes a differential device which includes two planetary gears 8 , 13 . Transmission 1 and electric machine 2 are arranged coaxially to an axis A, which coincides with the drive axis B, so that there is a coaxial output. The forward direction of travel is represented by the arrow 99 . As also in 3 can be seen, the transmission 1 and the electric machine 2 are aligned transversely to the direction of travel 99 of the vehicle 1000 .

4 1 shows a transmission 1 and an electric machine 2 as part of an electric drive in a preferred embodiment of the invention, as can be used, for example, in the drive train 100 of the vehicle 1000 . The electric drive comprises an electric machine 2, the rotor 2.1 of which is connected to an input shaft 11 of a first planetary gear set 7, an output shaft 12 arranged coaxially with the input shaft 11, and three shifting elements 3, 4, 5 for engaging gears.

The first planetary gear set 7 is designed as a stepped planetary gear. The stepped planetary gear has two planetary gears 7.3, 7.4 mounted on a planetary gear carrier 7.5 and having two different effective diameters. A first sun gear 7.1 of the planetary gear set 7 meshes with the larger effective diameter 7.3 of the planetary gears. A second sun gear 7.2 of the planetary gear set 7 meshes with the smaller effective diameter 7.4 of the planetary gears. A ring gear 7.6 of the planetary gear set 7 meshes with the larger effective diameter 7.3. The first sun gear 7.1 is connected to the first input shaft 11 in a torque-proof manner. The second sun gear 7.2 of the planetary gear set 7 is connected to the output shaft 12 in a rotationally fixed manner.

A first switching element 3 is designed to connect the planet carrier 7.5 of the planetary gear set 7 to the second switching element 4. If the first switching element 3 is actuated, then the planetary gear carrier 7.5 is non-rotatably connected to the second switching element. The second switching element 4 is designed to fix the first switching element 3 and the third switching element 5 to a non-rotatable component 0 . In the present case, the non-rotatable component 0 is a housing of the transmission 1. If the second shifting element 4 is actuated, the first and third shifting elements are accordingly fixed. The third shifting element 5 is designed to connect the ring gear 7.6 to the second shifting element 4. If the third switching element 5 is actuated, then the planetary carrier 7.6 is connected to the second switching element. The three switching elements 3, 4, 5 are each designed as a multi-plate clutch.

The input shaft 11 and the output shaft 12 are arranged coaxially with one another and arranged axially offset with respect to one another, that is to say the drive axis A and the output axis B coincide. The ring gear 7.6 is at least partially hollow. The planet carrier 7.5 is also partially hollow. The output shaft 12 designed as a solid shaft is through out the hollow shaft 7.5. The hollow shaft 7.5 in turn is guided through the hollow shaft 7.6.

The planetary gear set 7 is arranged radially inside the rotor 2.1 of the electric machine 2. The three switching elements 3, 4, 5 are arranged axially side by side. The result is the axial sequence of first planetary gearset 7, third shifting element 5, first shifting element 3 and second shifting element 4.

If the first switching element 3 and the second switching element 4 are engaged, a first electrical gear is displayed. By actuating the second switching element 4 and the third switching element 5, a second electrical gear is displayed. By actuating the first switching element 3 and the third switching element 5, a third electrical gear is displayed.

Thus, in the three gears, two of the three switching elements 3, 4, 5 are always closed. The electric drive according to the embodiment 4 or. 5 As a result, it has particularly low drag losses, in particular in comparison to an electric drive in which only one of three switching elements is actuated to represent the individual gears. Thus, in addition to an axially compact design, a particularly efficient transmission or a particularly efficient electric drive can be provided at the same time.

The shifting elements 3, 4, 5 are designed as frictional shifting elements in the form of multi-disc clutches in order to be able to additionally map a complete power shifting capability between the gears.

5 shows a switching matrix of the electric drive 4 . Three forward gears E1, E2 and E3 are listed in the rows of the matrix. An “X” in the columns of the switching matrix shows which of the switching elements 3, 4 and 5 are closed in which gear. Closing the first shifting element 3 and the second shifting element 4 creates a first gear E1, closing the second shifting element 4 and the third shifting element 5 creates a second gear E2, and closing the first shifting element 3 and the third shifting element 5 creates a third gear E3 shown. The third gear E3 is a so-called direct gear. The third shifting element 5 is open during the first gear E1. The first shifting element 3 is open during the second gear E2. The second shifting element 4 is open during the third gear E3. In first gear E1, the translation is greater than one. In third gear E3, the translation is exactly one. In second gear E2, the translation is between first and third gear.

Reference List

1

transmission

2

electric machine

2.1

rotor

2.2

stator

3

switching element

4

switching element

5

switching element

7

Planetary gear set, first

7.1

sun gear

7.2

sun gear

7.3

planet wheel

7.4

planet wheel

7.5

ring gear

7.6

planet carrier

8th

Planetary gear set, second

8.1

sun gear

8.2

planet carrier

8.3

ring gear

9

bevel gear differential

9.1

output gear

9.2

output gear

9.3

compensating element(s)

9.4

Differential cage, cage

9.11

first output shaft

9.12

second output shaft

11

input shaft

12

output shaft, output

13

Planetary gear set, third

13.1

sun gear

13.2

planet carrier

13.3

ring gear

14

Spur gear stage, one-stage, two-stage

14.1

spur gear

14.2

spur gear

14.3

spur gear

14.4

spur gear

99

driving direction

100

powertrain

1000

vehicle, car

A

drive axle

B

output axis

E1

first course

E2

second gear

E3

third gear

i

translation

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• WO 2014/029650 [0002]

Claims (15)

Electric drive for a vehicle, comprising: - An electric machine (2) whose rotor (2.1) is connected to an input shaft (11) of a first planetary gear set (7), an output shaft (12) arranged coaxially with the input shaft (11), and - three shifting elements (3, 4, 5) for engaging gears, - whereby, ◯ planet wheels (7.3, 7.4) mounted on a planet wheel carrier (7.5) have two different effective diameters, ◯ a first sun gear (7.1) of the planetary gear set (7) meshes with the larger effective diameter (7.3) of the planetary gears, ◯ a second sun gear (7.2) of the planetary gear set (7) meshes with the smaller effective diameter (7.4) of the planetary gears, ◯ a ring gear (7.6) of the planetary gear set (7) with the larger effective diameter (7.3) is in mesh, - the first sun gear (7.1) of the planetary gear set (7) being non-rotatably connected to the first input shaft (11), - the second sun gear (7.2) of the planetary gear set (7) being non-rotatably connected to the output shaft (12), - The three switching elements being arranged and designed in such a way that three different gear stages (E1, E2, E3) are provided by selectively closing two of the three switching elements (3, 4, 5). electric drive after claim 1 , wherein the planetary gear set (7) is arranged at least partially radially inside the electric machine (2). electric drive after claim 1 or 2 , - a first shifting element (3) being designed to connect the planet carrier (7.5) of the planetary gear set (7) to a second shifting element (4), - a third shifting element (5) being designed to connect the ring gear (7.6) to be connected to the second switching element (4), and - wherein the second switching element (4) is designed to fix the first switching element (3) and the third switching element (5) to a non-rotatable component (0). Electric drive according to one of the preceding claims, wherein the output shaft (12) is arranged inside the hollow input shaft (11) and inside the hollow planet carrier (7.5). Electric drive according to one of the preceding claims, wherein at least one of the shifting elements (3, 4, 5), preferably the first shifting element (3), is designed as a positive-locking shifting element, in particular as a claw clutch. Electric drive according to one of the preceding claims, wherein at least one of the three shifting elements (3, 4, 5) is designed as a frictional shifting element, in particular as a multi-plate clutch or a cone clutch. Drive train (100) with an electric drive according to one of Claims 1 until 6 and a differential device connected to the output shaft (12) of the first planetary gear set (7). drive train after claim 7 , wherein the differential device comprises a bevel gear differential (9) and a transmission gear in the form of a second planetary gear set (8), wherein - the sun gear (8.1) of the second planetary gear set (8) is connected to the second sun gear (7.2) of the first planetary gear set (7). - the planetary gear carrier (8.2) is connected to an input element (9.3) of the bevel gear differential (9), - the ring gear (8.3) is fixed to the non-rotatable component (0). drive train after claim 7 , wherein the differential device comprises a bevel gear differential (9) and a transmission gear in the form of a single-stage spur gear stage (14) with a first spur gear (14.1) and a second spur gear (14.2), wherein - the first spur gear (14.1) with the second sun gear (7.2 ) of the stepped planetary gear set (5) is non-rotatably connected and meshes with the second spur gear (14.2), - the second spur gear (14.2) is non-rotatably connected with an input element (9.3) of the bevel gear differential (9). drive train after claim 7 , wherein the differential device comprises a bevel gear differential (9) and a transmission gear in the form of a two-stage spur gear stage (14) with a first spur gear (14.1), a second spur gear (14.2), a third spur gear (14.3) and a fourth spur gear (14.4), - the third and fourth spur gears (14.3, 14.4) being non-rotatably connected to an intermediate shaft, - the first spur gear (14.1) being non-rotatably connected to the second sun gear (5.2) of the stepped planetary gear set (5) and to the third spur gear (14.3) meshes, - the fourth spur gear (14.4) meshes with the second spur gear (14.2), and - the second spur gear (14.2) is connected to a differential cage (9.4) of the bevel gear differential (9). drive train after claim 7 , wherein the differential device comprises a second planetary gear set (8) and a third planetary gear set (13), wherein - the sun gear (8.1) of the second planetary gear set (8) is connected to the second sun gear (7.2) of the first planetary gear set (7), - the planetary gear carrier (8.2) is connected to a first output shaft (8.4), - the ring gear (8.3) of the second planetary gear set (8) is connected to the sun gear (13.1) of the third planetary gear set (13), - the planetary gear carrier (13.2) to the non-rotatable Component (0) is fixed, - the ring gear (13.3) is connected to a second output shaft (13.4). drive train after claim 11 , wherein the second planetary gear set (8) is arranged radially inside (8) of the third planetary gear set (13). Powertrain according to one of Claims 7 until 12 , wherein the first planetary gear set (7) is arranged at least partially radially inside the rotor (2.1). Powertrain according to one of Claims 7 until 13 , wherein the differential device is arranged at least partially radially inside the rotor (2.1). Method for switching it electric drive and / or the drive train according to any one of the preceding claims, wherein - In a first gear (E1), the first switching element (3) and the second switching element (4) are closed and the third switching element (5) is opened, wherein - In a second gear (E2), the second switching element (4) and the third switching element (5) are closed and the first switching element (3) is opened, and wherein - In a third gear (E3), the first switching element (3) and the third switching element (5) are closed and the second switching element (4) is closed.

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