DE102018100649A1 - Drive unit for a vehicle with an electric motor and with a transmission - Google Patents

Abstract

The present invention relates to a drive unit (1) for a vehicle having an electric motor (10) and to a transmission (11), wherein the transmission (11) comprises a Ravigneaux set (12). According to the invention, the electric motor (10) has an output shaft (13), wherein the output shaft (13) is directly operatively connected to the single Ravigneaux set (12).

Description

The present invention relates to a drive unit for a vehicle with an electric motor and with a transmission, wherein the transmission has a Ravigneaux set.

STATE OF THE ART

From the DE 10 2014 205 550 A1 For example, a drive unit for a vehicle having an electric motor and a transmission is known, and the transmission has a Ravigneaux set. The Ravigneaux set is driven by a second gear, and the second gear is operatively connected to the electric motor. The second transmission has an output shaft for driving the Ravigneaux set, which interacts with a small sun wheel of the Ravigneaux set. The output shaft of the Ravigneaux set is formed by its ring gear. The overall arrangement of the second transmission between the electric motor and the Ravigneaux transmission is space-consuming and expensive, so it is desirable to reduce the structural complexity of a transmission between an electric motor and an axle of a vehicle. In particular, in purely electrically driven vehicles is always a small space for the gear provided to install this in a particularly advantageous arrangement on the electric motor or in a package arrangement with this.

In addition, the control of the transmission for the circuit of at least a first speed and a second speed is advantageous to perform, both for the transmission itself and for the control of the transmission with the corresponding control means, in particular brakes and clutches, the highest possible efficiency can be achieved should. Also, the mechanical load of, for example, one or more brakes should be minimized as possible. Furthermore, a good shift quality is to be striven for, in particular since load switching capability plays a major role in drive units with electric motors. The gear change from, for example, a first gear to a second gear should be possible while maintaining the load flow can be performed.

DISCLOSURE OF THE INVENTION

The object of the invention is the development of a drive unit for a vehicle with an electric motor and a transmission, wherein the transmission should have a first and at least a second gear, and wherein the transmission should occupy the smallest possible space and should have a low weight. In particular, it is the object of the invention to easily perform the control of the transmission to change between the two speed ranges even under load circuit, and the switching means for controlling the transmission should have a good efficiency and are operated as low as possible.

This object is achieved on the basis of a drive unit according to the preamble of claim 1 with the characterizing features. Advantageous developments of the invention are specified in the dependent claims.

The invention includes the technical teaching that the electric motor has an output shaft which is directly operatively connected to the single Ravigneaux set.

As a result, a particularly advantageous, compact design of the drive unit can be generated, since the Ravigneaux set can be arranged on the front side on a motor flange of the electric motor, since a Ravigneaux set has a substantially cylindrical design. In particular, the Ravigneaux set can be formed very advantageous as a 2-stage transmission with a first gear and a second gear, which is sufficient for a purely electric drive. This is especially true when the drive motor is designed as an axial flux motor.

In particular, a first brake may be provided with which a planet carrier of the Ravigneaux set can be braked and a second brake may be provided with which a large sun gear of the Ravigneaux set can be braked.

The core idea of the invention is the simple design of a transmission with a Ravigneaux set, which can be controlled in an advantageous manner with a first brake and with a second brake. This results in a small space for the arrangement between the electric motor and, for example, an axle of a vehicle, and the Ravigneaux set can be performed minimal weight. Particularly advantageous is the control of the Ravigneaux set with a first and a second brake, so that in particular no clutch or other switching means are part of the transmission and its control. The Bremen can be controlled so that a particularly good load switching capability of the transmission is generated, in particular because the transmission has only a first and a second gear, between which even without interrupting a power flow can be switched back and forth.

A particular advantage is achieved when a small sun gear of the Ravigneaux set is directly drivingly connected to the output shaft of the electric motor. An output shaft of the transmission can be formed with further advantage by means of a ring gear of Ravigneaux sentence. It is also expedient to bring the output shaft with an intermediate shaft into engagement, wherein the intermediate shaft in turn is in engagement with an axle shaft.

The output shaft of the electric motor can rotate in a central axis, and as well as the electric motor of the Ravigneaux set can be arranged concentrically to the center axis in front of the electric motor. This creates a compact, compact arrangement, especially when the large sun gear, the small sun gear and the ring gear rotate about the center axis. The gear with the Ravigneaux set can be accommodated in a housing, which in particular forms an approximately cylindrical base body, which is arranged with particular advantage on the front side of the output side of the electric motor, wherein the electric motor can also form an approximately cylindrical base body.

A further advantageous arrangement is achieved when the first brake and the second brake are arranged concentrically to the center axis and / or one inside the other. The brakes are doing on the side opposite the arrangement of the electric motor side of the transmission, so that the brakes can be controlled, for example, electromechanical or electro-static, and by the front-side arrangement of the concentric nested brakes these can be easily accessed.

With further advantage, a freewheel unit is provided, wherein the freewheel unit is operatively connected to the planet carrier of the Ravigneaux set. The freewheel unit can be arranged with particular advantage adjacent to or in parallel with the first brake, in particular it can be provided that the freewheel unit with the first brake forms a structural unit.

If the electric motor is constructed according to the design of an axial flux motor, it may have a short design in the middle axis direction, so that the gear comprising the Ravigneaux set can be arranged in front of the, for example, cylindrically shaped electric motor. For example, the gearbox can be advantageously flanged with the housing to the Axialflussmotor, since Axialflussmotoren have a short approximately cylindrical design with an enlarged radial direction compared to radial flow motors diameter. In particular, axial flow motors are characterized by a lower maximum speed compared to radial flow motors, so that the embodiment of the drive unit according to the invention for a vehicle with a 2-stage transmission and an axial flow motor is particularly advantageous. The advantage arises from the fact that the disadvantage of the limited speed band of the axial flow motor can be overcome by the two speed steps, and on the axle shaft, a wide speed range can be generated despite the use of a Axialflussmotors.

With still further advantage, an oil supply unit is provided with which the electric motor, the transmission and / or an inverter for controlling the electric motor is supplied or cooled together with oil. Yet another advantage is achieved when the intermediate shaft has a parking lock.

To insert the first gear of the transmission, the first brake is optionally closed and the freewheel unit is designed so that it actively engages and rotatably supports the planet carrier against the housing of the transmission. Consequently, the first brake does not have to be closed because the freewheel unit can be designed so that it can support the full torque. Advantageously, the first brake is thus relieved and can be made smaller, especially in a forward acceleration of the vehicle, also leads the arrangement of the freewheel unit to a lower wear of the first brake. In the case of forward acceleration in the first drive stage, the greatest torque arises between the planet carrier and the housing of the transmission in the event of a blockage of the planet carrier, so that this high torque can be absorbed by the freewheel unit with particular advantage. The smaller design of the first brake results in a better efficiency, since drag losses can be reduced. In overrun mode when driving forwards, the first brake must be closed, whereas the freewheel unit is ineffective, but it should be noted that in overrun operation, in principle, a lower power throughput through the transmission. In particular, however, a recuperation can be done by the electric motor is driven via the transmission in overrun mode and thus can serve to generate electricity.

For a reverse drive in the first gear, the first brake remains closed, and the freewheel is again ineffective. If a coasting operation is set during reversing despite low occurrence, recuperation can also take place via the electric motor, and the freewheel is active and holds the planet carrier against the housing, whereas again the first brake is actually not needed, and this can be open or preferably be closed. On the other hand, the second brake remains basically open.

The second gear is set for forward travel, in which the first brake is open, and the freewheel is ineffective. On the other hand, the second brake is closed. A reverse drive in the second gear is not provided and can be prevented with a control unit for controlling the transmission.

By means of the inventive arrangement of the Ravigneaux transmission between the electric motor and the axle shaft or the intermediate shaft and the arrangement of the first brake in operative connection with the planet carrier and the second brake in operative connection with the large sun gear of Ravigneaux set a very good efficiency of the transmission is achieved , And the actuators for controlling the transmission, namely, the first and the second brake, are essentially spared and can be designed smaller in particular with the arrangement of the freewheel unit. Also, there is the advantage that the brakes are well controlled by the front-side arrangement in front of the Ravigneaux set, and the two brakes are running one inside the other, they can be constructed advantageously in a special way. The brakes act in each case against the housing of the transmission, so that unlike couplings no rotating components must be connected. The freewheel unit further forms a passive element that does not require active drive. The inventive design of the drive unit with only a first and a second brake for driving low differential speeds are achieved at the respective open brake, so that a particularly good efficiency. Furthermore, there is a simple operation, since the brakes have a stationary, non-rotating part, so that, for example, brake piston or other actuating means of the brake can be arranged resting in or on the housing of the transmission. Further, resting parts of the brakes allow the formation of the same with a higher heat capacity, since the blades made of steel, for example, of the brake do not rotate with and thus do not form rotating inertia, and it can be derived heat from the fins into the housing. The coolability also improves, since the steel plates do not rotate with and therefore can be cooled advantageous.

The oil supply unit may extend equally through the inverter, the electric motor and the transmission, in particular parts of the supply unit may be connected to corresponding fluid lines. The oil supply unit can be used for cooling the electric motor, the transmission and the inverter, and the oil supply unit can also serve for lubrication of the transmission and the electric motor.

For example, the oil supply unit includes an electric oil pump that carries oil from an oil sump through an oil-water heat exchanger. From this heat exchanger, the oil can be fed into the inverter, into the electric motor and back into the transmission. Instead of returning all of the oil to the oil sump, a first portion of the oil volume flow may be used to lubricate and cool the transmission and brakes, and a second portion of the oil may be stored in a reservoir within the transmission. Optionally, the entire oil volume flow can be led into the memory. From there, other components can be lubricated and cooled, such as gears, as well as the bearings for the components of the transmission. With special control of the oil pump, the oil reservoir in the transmission can be used to control the oil level in the transmission while keeping the oil level substantially low to minimize oil lubrication losses, thereby further improving the efficiency of the drive unit.

PREFERRED EMBODIMENT OF THE INVENTION

Further, measures improving the invention will be described in more detail below together with the description of a preferred embodiment of the invention with reference to a single figure. It shows the

Figure a schematic representation of the drive unit with the features of the invention.

The figure shows a schematic view of a drive unit 1 with the features of the present invention. The drive unit 1 includes an electric motor 10 that with an inverter 27 is controlled. The electric motor 10 acts via a gearbox 11 with an axle shaft 22 to drive for example a vehicle together. The axle shaft 22 may include, for example, a differential.

The inverter 27 is located on a first side of the electric motor 10 , so a control side, and the transmission 11 is located on a second side of the electric motor 10 , which forms a driven side. The electric motor 10 may for example have a cylindrical basic shape, which cylindrical basic shape and the transmission 11 can form, in particular with the housing 25 of the transmission 11 the latter being indicated only schematically. Consequently, the drive unit 1 form a compact unit, which has a total of approximately cylindrical basic shape, which is about a center axis 23 extends around and both the electric motor 10 as well as the transmission 11 includes. A particular advantage is achieved when both the electric motor 10 as well as the transmission 11 around the center axis 23 equally extend.

The gear 11 includes a Ravigneaux set 12 and the electric motor 10 has an output shaft 13 on that with a small sun gear 18 of the Ravigneaux theorem 12 is actively connected. The output of the gearbox 11 and thus the Ravigneaux theorem 12 is formed by a ring gear 20 that equally the output shaft 19 forms. This works with an intermediate shaft 21 together, and the intermediate shaft 21 is engaged with the axle shaft 22 , The intermediate shaft 21 includes according to the embodiment shown, a parking brake 28 , with which a rotary motion of the intermediate shaft 21 can be blocked. The components present as the intermediate shaft 21 and the axle shaft 22 are designated, in this case comprise respective teeth to be in engagement with other components or with each other.

To connect the Ravigneaux theorem 12 is a first brake 14 provided with a planet carrier 15 of the Ravigneaux theorem 12 can be slowed down, and it is a second brake 16 provided with a large sun gear 17 of the Ravigneaux theorem 12 can be slowed down. Furthermore, a freewheel unit 24 provided, which are in parallel arrangement to the first brake 14 located, and the planet carrier 15 can through the freewheel unit 24 in a direction of rotation about the center axis 23 against the case 25 of the transmission 11 be supported. The first brake 14 acts likewise with the planet carrier 15 Together, so that it also in both directions against the housing 25 can be slowed down. The second brake 16 is arranged so that the big sun gear 17 against the case 25 can be slowed down.

Another component 12 is through a carrier body 29 formed by the at least the output shaft 19 at least partially guided and / or stored and in the advantageous further the small sun gear 18 is stored. The big sun wheel 17 For example, in a hollow shaft of the small sun gear 18 be stored. Further, in particular technically designed bearings are in the Ravigneaux set 12 not shown for simplicity of illustration.

The drive unit 1 has an oil supply unit 26 on, which is shown only schematically and for cooling the inverter 27 and for cooling and / or lubrication of the electric motor 10 and for cooling and / or lubricating the Ravigneaux set 12 serves. This extends the oil supply unit 26 through the inverter 27 , by the electric motor 10 and by the Ravigneaux theorem 12 time. The indicated components of the oil supply unit 26 represent lubricants and coolants, which in relation to the inverter 27 can also serve only for its cooling. The oil supply unit 26 include a reservoir that can store oil.

The Ravigneaux set 12 further includes outer planet wheels 30 and inner planet gears 31 , and the outer planet gears 30 comb inside inside the ring gear 20 and work with both the big sun gear 17 as well as with the inner planet wheels 31 together, the latter in turn with the small sun gear 18 interact. The active compounds mainly comprise the teeth of the components with each other.

In a manner not shown in detail there is advantageously the possibility of the first brake 14 and the second brake 16 to control by means of electromechanical or electro-hydrostatic actuator systems, in particular to the brakes 14 . 16 to close and open. The illustration shows that the brakes 14 and 16 frontally on the Ravigneaux set 12 are arranged so that a particularly advantageous connection of hydraulic lines and controls with the brakes 14 . 16 is possible.

The invention is not limited in its execution to the above-mentioned preferred embodiment. Rather, a number of variants is conceivable, which makes use of the illustrated solution even with fundamentally different types of use. All of the claims, the description or the drawings resulting features and / or advantages, including structural details or spatial arrangements may be essential to the invention both in itself and in various combinations.

LIST OF REFERENCE NUMBERS

1

drive unit

10

electric motor

11

transmission

12

Ravigneaux set

13

output shaft

14

first brake

15

planet carrier

16

second brake

17

big sun wheel

18

small sun wheel

19

output shaft

20

ring gear

21

intermediate shaft

22

axle shaft

23

mid-axis

24

Freewheel unit

25

casing

26

Oil supply unit

27

inverter

28

parking lock

29

support body

30

outer planetary gear

31

inner planet wheel

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been 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.

Cited patent literature

• DE 102014205550 A1 [0002]

Claims (10)

Drive unit ( 1 ) for a vehicle with an electric motor ( 10 ) and with a transmission ( 11 ), whereby the transmission ( 11 ) a Ravigneaux sentence ( 12 ), characterized in that the electric motor ( 10 ) an output shaft ( 13 ) with the only Ravigneaux theorem ( 12 ) is directly operatively connected. Drive unit ( 1 ) according to claim 1, characterized in that - a first brake ( 14 ) is provided, with a planet carrier ( 15 ) of the Ravigneaux theorem ( 12 ) and wherein - a second brake ( 16 ) is provided, with a large sun gear ( 17 ) of the Ravigneaux theorem ( 12 ) is brakable. Drive unit ( 1 ) according to claim 1 or 2, characterized in that a small sun gear ( 18 ) of the Ravigneaux theorem ( 12 ) with the output shaft ( 13 ) is directly drivingly connected. Drive unit ( 1 ) according to one of claims 1 to 3, characterized in that an output shaft ( 19 ) of the transmission ( 11 ) by means of a ring gear ( 20 ) of the Ravigneaux theorem ( 12 ) is formed. Drive unit ( 1 ) according to claim 4, characterized in that the output shaft ( 19 ) with an intermediate shaft ( 21 ) and wherein the intermediate shaft ( 21 ) with an axle shaft ( 22 ) is engaged. Drive unit ( 1 ) according to one of the preceding claims, characterized in that the output shaft ( 13 ) of the electric motor ( 10 ) in a center axis ( 23 ), the Ravigneaux theorem ( 12 ) concentric with the center axis ( 23 ) in front of the electric motor ( 10 ) is arranged. Drive unit ( 1 ) According to claim 6, characterized in that the large sun gear ( 17 ), the small sun wheel ( 18 ) and the ring gear ( 20 ) about the center axis ( 23 ) are rotatably arranged. Drive unit ( 1 ) according to one of the preceding claims, characterized in that the first brake ( 14 ) and the second brake ( 16 ) concentric with the center axis ( 23 ) and / or are arranged one inside the other and / or that a freewheel unit ( 24 ) is provided, wherein the freewheel unit ( 24 ) with the planet carrier ( 15 ) is operatively connected and / or wherein the freewheel unit ( 24 ) adjacent to and acting in parallel with the first brake ( 14 ) is arranged and / or a structural unit with the first brake ( 14 ). Drive unit ( 1 ) according to one of the preceding claims, characterized in that the electric motor ( 10 ) is designed according to the design of an axial flux motor and / or wherein the transmission ( 11 ) a housing ( 25 ), which is connected to the electric motor ( 10 ) is flanged. Drive unit ( 1 ) according to one of the preceding claims, characterized in that an oil supply unit ( 26 ) is provided, with which the electric motor ( 10 ), The gear ( 11 ) and / or an inverter ( 27 ) for controlling the electric motor ( 10 ) can be supplied together with oil.

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