DE102019206954A1 - Drive axle for an electrically powered vehicle - Google Patents

Abstract

The invention relates to a drive axle with two drive wheels (R1, R2) and a common wheel axle (a) for an electrically drivable vehicle, comprising two axially parallel electrical machines (EM1, EM2), two coaxially to the wheel axle (a) arranged side by side and coupled to one another Planetary sets (PS1, PS2), which each have a ring gear shaft (HR1, HR2), a sun shaft (SO1, SO2) and a spider shaft (ST1, ST2) and form a two-speed gearbox (G), an axle differential (DI) on the Wheel axle (a), whereby the first planetary set (PS1) can be driven via the ring gear shaft (HR1) from the first electrical machine (EM1) and the second planetary set (PS2) via the ring gear shaft (HR2) from the second electrical machine (EM2), wherein the first planetary gear set (PS1) and the second planetary gear set (PS2) are coupled via a common spider shaft (ST1 / ST2) and the common spider shaft (ST1 / ST2) is the transmission output shaft (GAW) of the two-speed gearbox ( G) forms and drives the differential (DI).

Description

The invention relates to a drive axle with two drive wheels and a common wheel axle for an electrically drivable vehicle, comprising two axially parallel electrical machines, two coaxially to the wheel axle arranged next to each other, coupled with each other, each having a ring gear shaft, a sun shaft and a spider shaft and a two-speed gear -Manual transmission form, and an axle differential on the wheel axle.

Through the DE 10 2009 002 437 A1 a purely electrically powered vehicle was known in several variants, one variant according to 2 a purely electrically drivable rear axle with individual wheel drives, ie a so-called individual wheel drive. Each drive wheel is assigned an electrical machine with a downstream gearbox, the two individual wheel drives being separate from one another. The manual transmissions are designed as two-speed transmissions and are shifted by means of a dog clutch, ie an interruption in tractive force occurs during the shifting process. If, for example, only the transmission on the right-hand side, which drives the right wheel, is shifted, a yaw moment occurs around the vertical axis of the vehicle which tries to steer the vehicle to the right as a result of the interruption in tractive force for the right wheel. In order to avoid such a yaw moment, the shifts are therefore carried out simultaneously on both sides. On the other hand, a yaw moment, e.g. B. be desirable when cornering to improve the agility of the vehicle. In such a case, the yaw moment can be generated specifically by a different torque distribution on the right and left drive wheel (so-called torque vectoring).

An object of the invention is to provide, in an electric vehicle, e.g. H. an electrically drivable vehicle, the drive components, d. H. to arrange the electrical machines and the gearbox in the area of the drive axle to save space and weight.

The invention comprises the features of claim 1. Advantageous embodiments emerge from the subclaims.

According to the invention, an axially parallel arrangement of the electrical machines and an arrangement of a two-speed gearbox which is coaxial to the wheel axis and which has two sets of tarpaulins arranged side by side and coupled via a common spider shaft is provided for a drive axle for an electric vehicle. Each electrical machine drives a planetary gear set, the outputs of both planetary gear sets being summed up via the coupling shaft and fed to a common transmission output shaft. The power of the transmission output shaft is distributed to both drive wheels via an axle differential.

According to a preferred embodiment, a spur gear stage, which is driven by the electrical machine, is connected upstream of each planetary set. The speed of the electrical machine is reduced by the spur gear stage.

According to a further preferred embodiment, the ring gears of the ring gear shafts of both planetary sets have external gears. The ring gear shafts of both planetary sets thus have a double function, namely on the one hand as a ring gear of the planetary gear and on the other hand as the output gear of the spur gear stage.

According to a further preferred embodiment, the spur gear stages each have intermediate gears which are arranged between the drive gears and the output gears or the externally toothed ring gears. In this way, the distance between the axes of the electrical machines and the wheel axis caused by the axial offset can be bridged spatially.

According to a further preferred embodiment, two switching elements are assigned to each planetary set, which are preferably designed as claw switching elements. The switching elements are preferably operated by actuators.

According to a further preferred embodiment, the first gear is activated by closing the shift element A. formed, whereby the sun shaft is coupled to the housing, ie is held. The transmission ratio for the first gear then results from the speed of the driven ring gear shaft and the driven spider shaft.

According to a further preferred embodiment, the second gear is activated by closing the shift element B. educated; as a result, the planetary set in question is "blocked", ie it rotates in the block, which corresponds to a ratio of 1: 1. In principle, three locking variants are possible, namely sun shaft with ring gear shaft or ring gear shaft with spider shaft or spider shaft with sun shaft.

According to a further preferred embodiment, the electrical machines can be decoupled individually or together: this is done by selecting a neutral position in which neither of the two switching elements is closed. This is what is known as a sailing operation of the electric vehicle, ie free rolling possible without the drag of the rotating electrical machines.

According to a further preferred embodiment, a constant transmission stage is arranged between the transmission output shaft and the differential, which brings about a further reduction in the speeds of the electrical machines.

According to a further preferred embodiment, the constant transmission stage is designed as a third planetary gear set, the sun shaft of which is driven by the transmission output shaft, the ring gear shaft of which is held and which drives the spider shaft into the differential. The planetary set enables a coaxial design between drive and output.

According to a further preferred embodiment, the differential can be locked, specifically by a switching element, by means of which the housing of the differential is coupled to a differential output shaft. This creates a rigid connection between the two drive wheels, which are always driven at the same speed.

According to a further preferred embodiment, a constant transmission step is provided between the differential and a drive wheel, which is preferably arranged in the area close to the wheel or can also be integrated into the drive wheel. This means that the speed of the electrical machines is only reduced after the differential, which is therefore subjected to a lower torque. The two constant gear ratios are also designed as third planetary gear sets.

According to a further preferred embodiment, the two-speed gearbox is arranged between the electrical machines and a drive wheel. This means that the drive components are arranged asymmetrically.

According to a further preferred embodiment, the constant transmission stage is arranged coaxially to the wheel axle and between the electrical machines. The installation space between the axially parallel electrical machines is used for an axially close arrangement of drive components.

• 1 eine Antriebsachse für ein Elektrofahrzeug mit zwei elektrischen Maschinen in achsparalleler Anordnung, einem Zweigang-Schaltgetriebe und einem Achsdifferenzial,
• 2 die Antriebsachse gemäß 1, jedoch mit einem Sperrdifferenzial,
• 3 eine Antriebsachse mit zwei radnahen Konstantübersetzungsstufen und
• 4 die Antriebsachse gemäß 3, jedoch mit Sperrdifferenzial.

Exemplary embodiments of the invention are shown in the drawing and are described in more detail below, it being possible for further features and / or advantages to emerge from the description and / or the drawing. Show it

• 1 a drive axle for an electric vehicle with two electric machines in an axially parallel arrangement, a two-speed gearbox and an axle differential,
• 2 the drive axle according to 1 , but with a limited slip differential,
• 3 a drive axle with two constant gear ratios close to the wheel and
• 4th the drive axle according to 3 , but with limited slip differential.

1 shows as a first embodiment of the invention a drive axle 1 an electrically drivable vehicle, hereinafter also referred to as an electric vehicle for short, with two on one wheel axle a arranged drive wheels R1 , R2 . Axially parallel to the wheel axle a , ie with an offset b are a first electrical machine EM1 and a second electric machine EM2 arranged which via a two-speed manual transmission G and one on the wheel axle a arranged axle differential DI the drive wheels R1 , R2 drive. The two-speed manual transmission G comprises two planetary sets coupled with one another PS1 , PS2 , each of which switching elements A. , B. , C. , D. are assigned, which by a first actuator AK1 and a second actuator AK2 are operable. The first planetary set PS1 which from the first electric machine EM1 is drivable, includes a sun shaft SO1 , a ring gear shaft HR1 and a web wave ST1 . The second planetary set PS2 , which from the second electrical machine EM2 is drivable, includes a sun shaft SO2 , a ring gear shaft HR2 as well as a web wave ST2 , which with the web wave ST1 of the first planetary gear set PS1 is firmly connected and a common web shaft ST1 / ST2 forms. The common web shaft, also known as the coupling shaft ST1 / ST2 called, forms the transmission output shaft GAW of the two-speed manual transmission G . Every planetary set PS1 , PS2 is a spur gear stage SS1 , SS2 upstream. The ring gears of the ring gear shafts HR1 , HR2 the first and the second planetary gear set PS1 , PS2 each have an external toothing AZ1 , AZ2 on - in addition to the internal gearing. The electrical machines EM1 , EM2 each have drive shafts 1a , 1b which each drive a drive gear of the first and second spur gear stages. The output gears of the first and second spur gear stages SS1 , SS2 are through the ring gears with the external gears AZ1 , AZ2 formed, ie the ring gears are part of the spur gear stages SS1 , SS2 . Between those on the drive shafts 1a , 1b arranged drive gears and the output gears AZ1 , AZ2 are intermediate gears ZR1 , ZR2 arranged which the axial offset b , ie the distance between the electrical machines EM1 , EM2 to the wheel axle a bridge. 1 Figure 3 is a top view of the drive axle 1 , ie the plane of the drawing is an xy plane of the Electric vehicle. The axially parallel arrangement is particularly advantageous for electrical machines with a smaller diameter - this is also clearly shown in the drawing. Between the two-speed manual transmission G and the differential DI is a constant transmission stage, designed as a third planetary gear set PS3 with a sun wave SO3 a web wave ST3 and a ring gear shaft HR3 , arranged. The third planetary set PS3 is about the sun wave SO3 from the gearbox output shaft GAW driven, the ring gear shaft HR3 is fixed to the housing, and the spider shaft ST3 , which forms the output, is directly connected to the differential basket DIK of the differential DI connected. The output shafts of the differential DI , those with the reference numbers 2a , 2 B are designated, drive the drive wheels R1 , R2 at.

As can be seen from the drawing, the arrangement of the electrical machines EM1 , EM2 , the two planetary sets PS1 , PS2 and the differential DI asymmetrical with respect to one between the drive wheels R1 , R2 imaginary center plane. The two-speed manual transmission G is, according to the drawing, essentially on the right side of the two electric drive machines EM1 , EM2 or between the right drive wheel R2 and the two electrical machines EM1 , EM2 . The right output shaft 2 B of the differential DI is through hollow shafts of the planetary gear sets PS3 , PS1 , PS2 passed through.

The two-speed manual transmission G is via the switching elements A. , B. , C. , D. , which are preferably designed as claw switching elements, operated as follows: The switching elements A. , B. are the first planetary set PS1 and the switching elements C. , D. the second planetary set PS2 assigned and arranged in mirror image to one another. As a result of the claw shifting, there is an interruption of traction during the shifting process. It therefore makes sense that both planetary sets PS1 , PS2 are not switched simultaneously, but one after the other, because then the electrical machine that drives the planetary gear set that is not affected by the circuit is supported, ie via the common spider shaft ST1 / ST2 and the transmission output shaft GAW into the differential DI drives in. This means that there is no interruption in traction. The shifting process can be synchronized by the electrical machine that drives the planetary set affected by the shift.

The first gear for the first planetary gear set PS1 is by closing the switching element A. formed, causing the sun wave SO1 is coupled to the housing (shown by hatching), ie is held. The synchronization takes place here through the first electrical machine EM1 . The first planetary set PS1 then runs with a stationary transmission between the driven ring gear shaft HR1 and the driving shaft ST1 . The first gear for the second planetary gear set is analogous PS2 formed, ie by closing the switching element C. making the sun wave SO2 is coupled to the housing.

The second gear is activated by closing the shift element B. for the first planetary set PS1 or by closing the switching element D. for the second planetary set PS2 educated. In both cases, the planetary sets are “blocked” by coupling or “blocking” the sun shafts with the ring gear shafts, ie the first and second planetary sets PS1 , PS2 each run as a block, which corresponds to a ratio of 1: 1. The driving shaft ST1 or. ST2 thus runs at the same speed as the driven ring gear HR1 or. HR2 around. With not closed switching elements A. , B. or. D. , C. the result is a neutral position in which the first electrical machine EM1 or the second electric machine EM2 or both electrical machines EM1 , EM2 can be disconnected.

Instead of locking the sun shaft and the ring gear shaft, the sun shaft can also be locked with the spider shaft or the spider shaft with the ring gear shaft. In all three interlocking variants, the planetary gear set rotates as a block, i.e. H. with a transmission ratio of 1: 1 between input and output.

2 shows a drive axle as a further embodiment of the invention 2 , which is a variant of the drive axle 1 according to 1 represents. The difference compared to the drive axle 1 is simply that the differential DI is lockable. The same parts are denoted by the same reference numbers. A switching element E. connects the differential cage when closed DIK (also called differential housing) with the differential output shaft 2a . This creates a direct mechanical connection between the left drive wheel R1 and the right drive wheel R2 made so that both drive wheels R1 , R2 always have the same wheel speed.

3 shows a drive axle as a further embodiment of the invention 3 , which is a variant of the drive axle 1 according to 1 represents; The same reference numerals are used for the same parts. The difference compared to the drive axle 1 is that instead of the single constant translation stage PS3 in 1 at the drive axle 3 two constant gear ratios arranged close to the wheel PS3 are provided which - seen in the direction of force flow - between the differential DI and the two drive wheels R1 , R2 are arranged. Both constant gear ratios are the third planetary gear sets PS3 trained and correspond to the planetary gear set PS3 in 1 . The sun waves SO3 of the third planetary sets PS3 are from the differential output shafts 2a , 2 B driven, the ring gear shafts HR3 are fixed to the housing, and the web shafts ST3 form the output shafts, which the drive wheels R1 , R2 drive.

4th shows a drive axle as a further embodiment of the invention 4th , which is a variant of the drive axle 3 according to 3 represents, wherein the same reference numerals are used for the same parts. Different for the drive axle 4th is a switching element E. over which the differential DI can be blocked. With the switching element closed E. are the differential basket DIK and the differential output shaft 2a coupled together so that both differential output shafts 2a , 2 B are rigidly connected to each other.

List of reference symbols

1

Drive axle

1a

Drive shaft (EM1)

1b

Drive shaft (EM2)

2

Drive axle

2a

Output shaft

2 B

Output shaft

3

Drive axle

4th

Drive axle

A.

Switching element

a

Wheel axle

AK1

first actuator

AK2

second actuator

AZ1

External toothing ( HR1 )

AZ2

External toothing ( HR2 )

b

Offset

B.

Switching element

C.

Switching element

D.

Switching element

DI

differential

DIK

Differential basket

E.

Switching element

EM1

first electric machine

EM2

second electric machine

G

Two-speed manual transmission

GAW

Transmission output shaft

HR1

Ring gear shaft (PS1)

HR2

Ring gear shaft ( PS2 )

HR3

Ring gear shaft ( PS3 )

PS1

first planetary set

PS2

second planetary set

PS3

third planetary set

R1

first drive wheel

R2

second drive wheel

SO1

Sun wave ( PS1 )

SO2

Sun wave ( PS2 )

SO3

Sun wave ( PS3 )

SS1

first spur gear stage

SS2

second spur gear stage

ST1

Web shaft ( PS1 )

ST2

Web shaft ( PS2 )

ST3

Web shaft ( PS3 )

ZR1

Intermediate gear ( SS1 )

ZR2

Intermediate gear ( SS2 )

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed 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

• DE 102009002437 A1 [0002]

Claims (15)

Drive axle with two drive wheels (R1, R2) and a common wheel axle (a) for an electrically drivable vehicle, comprising - two axially parallel electrical machines (EM1, EM2), - two planetary sets (PS1, PS2) which are arranged coaxially to the wheel axis (a) and are coupled to one another, each of which has a ring gear shaft (HR1, HR2), a sun shaft (SO1, SO2) and a spider shaft (ST1, ST2) and a two-speed Form manual transmission (G), - a differential (DI) on the wheel axle (a), - The first planetary gear set (PS1) being drivable via the ring gear shaft (HR1) from the first electrical machine (EM1) and the second planetary gear set (PS2) via the ring gear shaft (HR2) from the second electrical machine (EM2), the first planetary gear set (PS1) and the second planetary gear set (PS2) are coupled via a common spider shaft (ST1 / ST2) and - The common spider shaft (ST1 / ST2) forms the transmission output shaft (GAW) of the two-speed manual transmission (G) and drives the differential (DI). Drive axle after Claim 1 , characterized in that a first spur gear stage (SS1) is connected between the first electrical machine (EM1) and the first planetary set (PS1) and a second spur gear stage (SS2) is connected between the second electrical machine (EM2) and the second planetary set (PS2) . Drive axle after Claim 2 , characterized in that the ring gear shafts (HR1, HR2) of the first and second planetary gear sets (PS1, PS2) each have ring gears with external teeth (AZ1, AZ2) and that the ring gears are the output gears of the first and second spur gear stages (SS1, SS2 ) form. Drive axle after Claim 2 or 3 , characterized in that the spur gear stages (SS1, SS2) each comprise an intermediate gear (ZR1, ZR2). Drive axle after Claim 1 , 2 , 3 or 4th , characterized in that two switching elements (A, B, C, D) are assigned to each planetary set (PS1, PS2). Drive axis according to one of the Claims 1 to 5 , characterized in that the first gear is formed by holding the sun shaft (SO1, SO2) of the first and / or the second planetary gear set (PS1, PS2). Drive axis according to one of the Claims 1 to 6th , characterized in that the second gear is formed by locking two of the three shafts (SO1, HR1, ST1; SO2, HR2, ST2) of the first and / or the second planetary gear set (PS1, PS2). Drive axis according to one of the Claims 1 to 7th , characterized in that one electrical machine or both electrical machines (EM1, EM2) can be decoupled. Drive axis according to one of the Claims 1 to 8th , characterized in that a constant transmission stage (PS3) is arranged between the transmission output shaft (GAW) of the two-speed manual transmission (G) and the differential (DI). Drive axle after Claim 9 , characterized in that the constant transmission stage is designed as a third planetary gear set (PS3) with a sun shaft (SO3), a ring gear shaft (HR3) and a spider shaft (ST3), the sun shaft (SO3) being driven by the gear output shaft (GAW), the ring gear shaft (HR3) is held and the spider shaft (ST3) drives the differential (DI). Drive axis according to one of the Claims 1 to 10 , characterized in that the differential (DI) can be locked by actuating a switching element (E). Drive axis according to one of the Claims 1 to 8th , characterized in that a constant transmission stage (PS3) is arranged between the differential (DI) and the drive wheels (R1, R2). Drive axle after Claim 12 , characterized in that the two constant transmission stages are each designed as third planetary gear sets (PS3) with a sun shaft (SO3), a ring gear shaft (HR3) and a spider shaft (ST3), the sun shaft (SO3) each from an output shaft (3a, 3b ) of the differential (DI) can be driven, the ring gear shaft (HR3) is held in place and the spider shaft (ST3) each drives a drive wheel (R1, R2). Drive axis according to one of the Claims 1 to 13 , characterized in that the first and the second planetary set (PS1, PS2), seen in the direction of the wheel axis (a), arranged between the first and the second electrical machine (EM1, EM2) and one of the two drive wheels (R1, R2) are. Drive axle after Claim 14 , characterized in that the constant gear ratio (PS3), in the direction perpendicular to the wheel axis (a) seen, is arranged between the electrical machines (EM1, EM2).

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