EP2959185A1

EP2959185A1 - Multi-stage planetary transmission

Info

Publication number: EP2959185A1
Application number: EP14701081.3A
Authority: EP
Inventors: Stefan Beck; Christian Sibla; Wolfgang Rieger
Original assignee: ZF Friedrichshafen AG
Current assignee: ZF Friedrichshafen AG
Priority date: 2013-02-22
Filing date: 2014-01-22
Publication date: 2015-12-30
Also published as: US20160131226A1; WO2014127943A1; CN105008766B; US9581222B2; CN105008766A; DE102013202888A1

Abstract

The invention relates to a multi-stage planetary transmission for a vehicle, comprising a housing (11), a first shaft (1) being provided as the drive (An) and a second shaft (2), arranged axially parallel thereto, as the output (Ab). Three planetary gear sets (RS1, RS2, RS3) and additional shafts (3, 4, 5, 6, 7, 8, 9) as well as six shift elements (K1, K2, K3, K4, B1, B2) are provided the actuation of which allows for a plurality of speeds, and machine elements (ST1, ST2) are provided for torque transmission between the drive (An) and the output (Ab). The first shaft (1) as the drive can be connected to the planet carrier (PT3) of the third planetary gear set (RS3), to the ring gear (HR1) of the first planetary gear set (RS1), to the sun gear (SR2) of the second planetary gear set (RS2), to the ring gear (HR3) of the third planetary gear set (RS3), to the ring gear (HR2) of the second planetary gear set (RS2), and to the first machine element (ST1), and the second shaft (2) as the output (Ab) is or can be connected to the first machine element (ST1) and to the second machine element (ST2).

Description

Multi-speed transmission in planetary construction

The present invention relates to a planetary multi-speed transmission for a vehicle according to the closer defined in the preamble of claim 1. Art.

For example, from the publication DE 10 2007 014 150 A1 a power-shiftable multi-speed transmission is known. In the multi-speed transmission, the drive shaft is connected via a torsional vibration damper fixed to a first shaft of a first shaft train. A parallel arranged second shaft strand includes, among others, designated as the shaft two output shaft. The two wave strands are connected to each other via three spur gear stages. On the first shaft train is a first three-shaft planetary gear. On the second shaft train are a second planetary gear and a third planetary gear. The multi-speed transmission thus comprises ten shafts, which communicate with each other via three spur gears and three planetary gears. To switch the eight forward gears and the one reverse gear five switching elements are necessary. The envisaged switching elements are hydraulically actuated.

To reduce hydraulic losses, the switching elements are to be arranged easily accessible from the outside. However, in a front-transverse installation of the transmission in a vehicle only a limited axial space is available.

The present invention is based on the object to provide a multi-speed transmission with the highest possible number of gear ratios and good accessibility of the switching elements at the same time good gear efficiency and the lowest possible axial space requirement.

This object is achieved by the features of claim 1, wherein there are advantageous developments of the invention from the dependent claims and the description and the drawings. Accordingly, a powershiftable multi-speed planetary gear or a multi-speed planetary gear for a vehicle is proposed with a housing, wherein the drive or the drive shaft and the output or the output shaft are arranged axially parallel to each other for a preferred front transverse installation. The multistage transmission according to the invention comprises only nine shafts, three planetary gear sets and only six shift elements in order to realize at least nine forward gears and one reverse gear can. Furthermore, preferably only two machine elements are provided for coupling drive and output.

Characterized in that the first shaft as a drive to the planet carrier of the third planetary gear set, with the ring gear of the first Planentenradsatzes, with the ring gear of the third planetary, with the sun gear of the second planetary gear, with the ring gear of the second planetary gear set and with the first machine element each detachably connected or in each case is connectable and that the second shaft is connected as an output to the first machine element and the second machine element or detachably connected or connectable, results in a multi-step transmission according to the invention, which enables an efficiency-improving and thus needs-based operation of the switching elements, wherein the Advantageously small number of transmission elements of the multi-speed transmission to the front transverse construction are interleaved with each other such that a particularly axial space-saving arrangement is made possible. In addition to the improved efficiency, there are also low component loads and low construction costs.

The good accessibility of the switching elements can be realized, inter alia, on the one hand by the use of brakes as switching elements and on the other hand by the use of couplings as switching elements, which are preferably positioned on outer shafts preferably on the drive and the output in the multi-step transmission according to the invention. Due to the low construction costs result in an advantageous manner low production costs and low weight of the multi-speed transmission according to the invention. As part of a possible embodiment of the invention can be provided that at least one spur gear or the like is used as a machine element for coupling or for torque transmission between the drive and output, which realizes the necessary translation to the output differential. Preferably, only two machine elements or spur gears are provided. However, other machine elements for torque or power transmission, such as chains, belts or the like can be used.

The planetary gear sets are arranged in the order of the first planetary gear set, the second planetary gear set and the third planetary gear set arranged in the axial direction, wherein preferably only minus planetary gear sets are provided. However, it is possible at locations where bondability allows one or more of the negative planetary gear sets to be converted into positive planetary gear sets when simultaneously changing the bridge gear and ring gear connections and increasing the amount of the standard ratio by one , A minus planetary gear set is known to be rotatably mounted on the planet gear planetary gears, which mesh with the sun gear and the ring gear of this planetary gear, so that the ring gear rotates with held planet carrier and rotating sun in the direction opposite to Sonnenraddrehrichtung. A plus planetary gear set is known to be rotatably mounted on its planet gear and meshing with each other inner and outer planetary gears, the sun gear of this planetary mesh with the inner planet gears and the ring gear of this planetary gear with the outer planetary gears, so that the ring gear with held planet carrier and rotating sun gear in the direction of Sonnenraddrehrichtung same direction turns.

As a starting element, a hydrodynamic torque converter or a hydrodynamic coupling can be used in the multistage transmission according to the invention. It is also conceivable that an additional starting clutch or an integrated starting clutch or starting brake be used. Furthermore, it is possible that an electric machine or another power Z-power source is arranged on at least one of the shafts. In addition, at least one of the shafts a freewheel to the housing or to another shaft can be arranged.

Preferably, in the multistage transmission according to the invention, nine forward gears and at least one reverse gear can be switched via the switching elements provided. However, it is conceivable that further switching combinations are made possible by combining other switching elements, preferably for the fourth forward gear or for other gear ratios.

The term switching element is to be understood as meaning a switchable connection between two elements of the transmission, wherein the torque to be transmitted between these two elements is transmitted by means of force-locking or frictional engagement or by means of positive locking. If both elements of the switchable connection are rotatable, then the switching element is referred to as a coupling and if only one of the two elements of the switchable connection rotates, the switching element is referred to as a brake. In addition, the geometric position or sequence of the individual switching elements is freely selectable, as long as it allows the bindability of the elements. In this way, individual elements can be moved arbitrarily in their position. In addition, as far as the outer shape allows, a plurality of wheel sets can also be arranged radially one above the other, ie nested.

Embodiments of a force-locking switching element are multi-plate clutches or brakes, band brakes, cone clutches or brakes, electromagnetic clutches, magnetic powder clutches and electro-rheological coupling. Embodiments of a positive switching element are jaw clutches or brakes and gear couplings.

As a switching elements thus both friction and form-locking switching elements can generally be used. Preferably, due to the characteristic, in particular, the fourth switching element designed as a clutch can be designed as a claw switching element, as a result of which clear consumption advantages are achieved. Hereinafter, the present invention will be further explained with reference to the drawings. Show it:

Figure 1 is a schematic view of a first embodiment of a multi-speed transmission according to the invention;

Figure 2 is a schematic view of a second embodiment of the multi-speed transmission; and

Figure 3 is a circuit diagram for the various embodiments of the multi-speed transmission.

In FIGS. 1 and 2, an embodiment variant of the multi-speed transmission according to the invention in planetary design, for example as an automatic transmission or automatic transmission, is shown by way of example for a vehicle.

Regardless of the respective embodiment variants, the multistage transmission comprises a housing 1 1, which is indicated only schematically, with a first shaft 1 as the drive An and a second shaft 2 arranged parallel to the axis as the output Ab and further seven shafts 3, 4, 5, 6, 7, 8, 9. Furthermore, a first planetary gearset RS1, a second planetary gearset RS2 and a third planetary gearset RS3 are provided, which are preferably designed as negative planetary gear sets. For switching a plurality of gear ratios are designed as a clutch first switching element K1, designed as a clutch second switching element K2, designed as a clutch third switching element K3, designed as a clutch fourth switching element K4, designed as a brake fifth switching element B1 and designed as a brake sixth Switching element B2 provided.

For coupling or for torque transmission between drive input and output Ab, two arbitrary machine elements are preferably provided, which in the case of the embodiment variants are designed by way of example as first spur gear stage ST1 and as second spur gear stage ST2. In the first embodiment variant according to FIG. 1, the first spur gear stage ST1 comprises a fixed gear 12 which is connected to the fifth spur wheel Shaft 5 is connected, and an idler gear engaged with this 13, which is connected via the ninth shaft 9 and the fourth switching element K4 with the second shaft 2. The second spur gear ST2 comprises a fixed gear 14, which is connected to the sixth shaft 6, and a stationary gear engaged with the latter 15, which is connected to the second shaft 2. In contrast to the first embodiment variant comprises in the second embodiment according to Figure 2, the first spur gear ST1 a idler gear 12A, which is connected via the ninth shaft 9 and designed as a clutch fourth switching element K4 with the fifth shaft 5. The idler gear 12A is engaged with a fixed gear 13A which is connected to the second shaft 2.

With regard to the connection possibilities between the provided shafts 1, 2, 3, 4, 5, 6, 7, 8, 9, the planned three planetary gear sets RS1, RS2, RS3, the intended housing 1 1 and the provided switching elements K1, K2, K3, K4, B1, B2 and the proposed spur ST1, ST2 is the term -verbindbar- to understand that the elements described solvable example are connected via a switching element, so that the connection is closed when the switching element is activated and open when the switching element is not activated. The releasable connection may be adjacent to the switching element via at least one further element, such as e.g. a wave or the like can be realized. The term "connected" is to be understood as meaning that the elements described are connected to one another so to speak, so that they are not permanently detachable. It may be a direct or indirect fixed connection e.g. be realized via other elements.

According to the invention, it is provided in the multi-stage transmission that the first shaft 1 is detachably connected or connectable as a drive An with the planet carrier PT3 of the third planetary gearset RS3 and the ring gear HR1 of the first planetary gearset RS1. Furthermore, the first shaft 1 can be connected to the sun gear SR2 of the second planetary gearset RS2 and to the ring gear HR3 of the third planetary gearset RS3. In addition, the first shaft 1 can be connected to the ring gear HR2 of the second planetary gear set RS2 and the first machine element or the first spur gear ST1. Depending on the embodiment variant, the second shaft 2 as the output Ab is connected to the first machine element or the first spur gear. Fe ST1 and connected to the second machine element or the second spur gear ST2 or connectable.

In the first embodiment according to FIG. 1, the second shaft 2 is connected to the fixed gear 15 of the second spur gear ST2. Furthermore, the second shaft 2 can be connected via the fourth shift element K4 designed as a clutch and via the ninth shaft 9 to the idler gear 13 of the first spur gear ST1.

In the second embodiment according to Figure 2, the second shaft 2 with the fixed gear 13A of the first spur gear ST1 and the fixed gear 15 of the second spur gear ST2 each directly fixed. The idler gear 12A of the first spur gear ST1 is detachably connected or connectable to the first shaft 1 via the ninth shaft 9 and via the fourth shifting element K4 designed as a clutch and the fifth shaft 5 and via the third shifting element K3 designed as a clutch. Furthermore, the first spur gear ST1 can be connected via the ninth shaft 9 and via the fourth shifting element K4 designed as a clutch and via the fifth shaft 5 to the ring gear HR2 of the second planetary gearset RS2.

2, the fourth switching element K4 designed as a clutch, which connects the first spur gear stage ST1 to the output shaft or to the second shaft 2, is transferred to the other spur gear side, that is to the side of the transmission input shaft or the first shaft 1 positioned. For this purpose, the original fixed gear 12 to the idler gear 12A and the original idler gear 13 to the fixed gear 13A.

In the multistage transmission according to the invention, the first shaft 1 via the first switching element K1 designed as a clutch and via the third shaft 3 with the planet carrier PT3 of the third planetary gear set RS3 and with the ring gear HR1 of the first planetary gear set RS1, so that the planet carrier PT3 of the third planetary gear set RS3 and the ring gear HR1 of the first planetary gear set RS1 are connected to each other, wherein the planet carrier PT3 of the third planetary gear set RS3 and the ring gear HR1 of the first planetary gear set RS1 via the third shaft 3 and the fifth executed as a brake Switching element B1 with the housing 1 1 is connectable. Furthermore, the first shaft 1 can be connected via the second switching element K2 designed as a clutch and via the fourth shaft 4 to the sun gear SR2 of the second planetary gearset RS2 and to the ring gear HR3 of the third planetary gearset RS3. The first shaft 1 is connectable or connected in the first embodiment via the third switching element K3 designed as a clutch and via the fifth shaft 5 both to the fixed gear 12 of the first spur gear ST1 and to the ring gear HR2 of the second planetary gearset RS2. In the second embodiment variant, the first shaft 1 is connected via the third switching element K3 designed as a clutch, via the shaft 5 and via the fourth switching element K4 designed as a clutch and via the shaft 9 to the idler gear 12A of the first spur gear stage 1, and furthermore the first one Shaft 1 via the coupling element formed as a third switching element K3 and via the shaft 5 with the ring gear HR2 of the second planetary gearset RS2 connectable.

Regardless of the respective embodiment variant, the second spur gear ST2 is connected via the sixth shaft 6 to the sun gear SR1 of the first planetary gearset RS1. In addition, the planet carrier PT1 of the first planetary gear set RS1 is connected via the seventh shaft 7 to the planet carrier PT2 of the second planetary gearset RS2. In addition, the sun gear SR3 of the third planetary gear set RS3 can be connected to the housing 11 via the eighth shaft 8 and via the sixth shifting element B2 designed as a brake.

FIG. 3 shows a circuit diagram or a switching matrix for the two equivalent transmission variants according to FIGS. 1 and 2. In the circuit diagram to be closed or to be activated switching elements K1, K2, K3, K4, B1, B2 are tabulated to realize the various gear ratios, each gear ratio is a ratio i and indicated between different gear ratios of the respective gear jump φ. In addition to the new forward gears G1, G2, G3, G4, G5, G6, G7, G8, G9 and the indicated reverse gear R, additional additional shift combinations are indicated as alternative fourth forward gears M1, M2, M3. Overall, the circuit diagram shows that the proposed multistage transmission has optimized transmission series with low absolute and relative speeds as well as low planetary gear set and shift element torques. has. Furthermore, the selected wheel set arrangements result in good toothing efficiencies and low drag torques.

As preferred stand ratios, in the first planetary gearset RS1 a value of about i ₀ = -1, 600, in the second planetary gear set RS2 a value of about i ₀ = -3,700 and in the third planetary gear set RS3 a value of about i ₀ = -1 , 750 are used. In the case of the first spur gear ST1, a value of about I _S TI = -, 345 is selected as the state ratio and a value of about isT2 = -1, 000 is selected for the second spur gear ST2. In addition, it follows from the circuit diagram that three switching elements are closed to switch all the gear stages G1, G2, G3, G4, G5, G6, G7, G8, G9, R, M1, M2 and M2.

In detail, it follows from the shift pattern according to FIG. 3 that the second shift element K2 designed as a clutch, the fourth shift element K4 designed as a clutch and the sixth shift element B2 designed as a brake are closed or activated to realize the first forward gear G1. For switching the second forward gear G2, the first shifting element K1 designed as a clutch, the fourth shifting element K4 designed as a clutch and the sixth shifting element B2 designed as a brake are closed or activated. For switching the third forward gear G3, the first shifting element K1 designed as a clutch, the second shifting element K2 designed as a clutch and the fourth shifting element K4 designed as a clutch are closed or activated. For shifting the fourth forward gear G4, the second shifting element K2 designed as a clutch, the third shifting element K3 designed as a clutch and the fourth shifting element K4 designed as a clutch are closed or activated. For switching the fifth forward gear G5, the first shifting element K1 designed as a clutch, the second shifting element K2 designed as a clutch and the third shifting element K3 designed as a clutch are closed or activated. For switching the sixth forward gear G6, the first shifting element K1 designed as a clutch, the third shifting element K3 designed as a clutch and the sixth shifting element B2 designed as a brake are closed or activated. For switching the seventh forward gear G7 designed as a clutch second switching element K2, designed as a clutch third switching element K3 and the executed as a brake sixth switching element B2 closed or activated. For switching the eighth forward gear G8, the third shifting element K3 designed as a clutch, the fifth shifting element B1 designed as a brake and the sixth shifting element B2 designed as a brake are closed or activated. For shifting the ninth forward gear G9, the second shifting element K2 designed as a clutch, the third shifting element K3 designed as a clutch and the fifth shifting element B1 designed as a brake are closed or activated. Finally, for switching the reverse gear R, the second shifting element K2 designed as a clutch, the fourth shifting element K4 designed as a clutch and the fifth shifting element B1 designed as a brake are closed or activated.

With regard to the shifting combinations of the alternative fourth forward gears M1, 2, M3, it is provided that for switching the alternative fourth forward gear M1, the third shifting element K3 designed as a clutch, the fourth shifting element K4 designed as a clutch and the fifth shifting element B1 designed as a clutch are closed or activated are. For switching the alternative fourth forward gear 2, the third shifting element K3 designed as a clutch, the fourth shifting element K4 designed as a clutch and the sixth shifting element B2 designed as a brake are closed or activated. Furthermore, for switching the alternative fourth forward gear M3, the first shifting element K1 designed as a clutch, the third shifting element K3 designed as a clutch and the fourth shifting element K4 designed as a clutch are closed or activated.

REFERENCE CHARACTERS

1 first shaft as drive

2 second shaft as the output

3 third wave

4 fourth wave

5 fifth wave

6 sixth wave

7 seventh wave

8th wave

9th ninth wave

1 1 housing

K1 first switching element as a coupling

K2 second switching element as a clutch

Κ3 third switching element as a clutch

Κ4 fourth switching element as a clutch

Β1 fifth switching element as a brake

Β2 sixth switching element as a brake

RS1 first planetary gear set

RS2 second planetary gear set

RS3 third planetary gear set

SR1 sun gear of the first planetary gear set

ΡΤ1 Pianetenradtrager the first Pianetenradsatzes

HR1 ring gear of the first Pianetenradsatzes

SR2 sun gear of the second planetary gear set

ΡΤ2 Pianetenradtrager the second Pianetenradsatzes

HR2 ring gear of the second Pianetenradsatzes

SR3 sun gear of the third Pianetenradsatzes

P3 Pianetenradtrager the third Pianetenradsatzes

HR3 ring gear of the third Pianetenradsatzes

ST1 machine element (first spur gear stage)

ST2 machine element (second spur gear stage)

12 fixed gear of the first spur gear 12A idler gear of the first spur gear stage

13 idler gear of the first spur gear stage

13A Fixed gear of the first spur gear stage

14 fixed gear of the second spur gear

15 fixed wheel of the second spur gear

G1 first forward gear

G2 second forward gear

G3 third forward gear

G4 fourth forward gear

G5 fifth forward gear

G6 sixth forward gear

G7 seventh forward gear

G8 eighth forward gear

G9 ninth forward gear

R reverse gear

M1 alternative fourth gear

M2 alternative fourth gear

M3 alternative fourth gear

i translation

i ₀ Stand translations of the planetary gear sets i _ST1 Stand translation of the first spur gear stage i _ST2 Stand translation of the second spur gear stage φ Gear jump

Claims

claims

1 . Multi-stage gear in planetary design for a vehicle with a housing (1 1), wherein a first shaft (1) as a drive (An) and an axially parallel arranged second shaft (2) as the output (Ab) are provided, wherein three planetary gear sets (RS1, RS2, RS3) and further shafts (3, 4, 5, 6, 7, 8, 9) and six switching elements (K1, K2, K3, K4, B1, B2) are provided by the actuation of multiple gear stages are feasible, and wherein machine elements (ST1, ST2) for torque transmission between the drive (An) and output (Ab) are provided, characterized in that the first shaft (1) as a drive with the planet carrier (PT3) of the third planetary gear set (RS3), with the ring gear ( HR1) of the first planetary gearset (RS1), with the sun gear (SR2) of the second planetary gearset (RS2), with the ring gear (HR3) of the third planetary gearset (RS3), with the ring gear (HR2) of the second planetary gearset (RS2) and with the first machine element (ST1) is connectable, and that the z wide shaft (2) as output (Ab) with the first machine element (ST1) and with the second machine element (ST2) is connected or connectable.

2. Multi-speed transmission according to claim 1, characterized in that as machine elements spur gears (ST1, ST2) or chains are provided.

3. Multi-step transmission according to claim 1 or 2, characterized in that the first shaft (1) via the clutch designed as the first switching element (K1) and the third shaft (3) with the planet carrier (PT3) of the third planetary gear set (RS3) and with the ring gear (HR1) of the first planetary gear set (RS1) is connectable, wherein the planet carrier (PT3) of the third planetary gear set (RS3) and the ring gear (HR1) of the first planetary gear set (RS1) are interconnected.

4. Multi-speed transmission according to claim 3, characterized in that the planet carrier (PT3) of the third planetary gear set (RS3) and the ring gear (HR1) of the first planetary gear set (RS1) via the third shaft (3) and via the fifth switching element designed as a brake ( B1) with the housing (1 1) is connectable.

5. Multi-step transmission according to one of the preceding claims, characterized in that the first shaft (1) via the second switching element (K2) designed as a clutch and via the fourth shaft (4) with the sun gear (SR2) of the second planetary gear set (RS2) and with the ring gear (HR3) of the third planetary gear set (RS3) is connectable.

6. Multi-step transmission according to one of the preceding claims, characterized in that the first shaft (1) via the third switching element designed as a clutch (K3) and the fifth shaft (5) with the first spur gear (ST1) and with the ring gear (HR2 ) of the second planetary gear set (RS2) is connectable.

7. Multi-speed transmission according to one of the preceding claims, characterized in that the second shaft (2) with the fixed gear (15) of the second spur gear (ST2) is connected and that the second shaft (2) via the fourth switching element (K4 ) and via the ninth shaft (9) with the idler gear (13) of the first spur gear (ST1) is connectable.

8. Multi-speed transmission according to one of claims 1 to 6, characterized in that the second shaft (2) with the fixed gear (13A) of the first spur gear (ST1) and with the fixed gear (15) of the second spur gear (ST2) is connected, and that the idler gear (12A) of the first spur gear (ST1) via the ninth shaft (9) and via the fourth switching element (K4) and the fifth shaft (5) designed as a clutch and the third switching element (K3) designed as a clutch with the first Shaft (1) is connectable.

9. Multi-speed transmission according to claim 8, characterized in that the idler gear (12A) of the first spur gear (ST1) via the ninth shaft (9) and via the coupling designed as the fourth switching element (K4) and the fifth shaft (5) with the ring gear (HR2) of the second planetary gear set (RS2) is connectable.

10. Multi-step transmission according to one of the preceding claims, characterized in that the fixed gear (14) of the second spur gear (ST2) on the sixth shaft (6) is connected to the sun gear (SR1) of the first planetary gear set (RS1).

1 1. Multi-step transmission according to one of the preceding claims, characterized in that the planet carrier (PT1) of the first planetary gear set (RS1) via the seventh shaft (7) to the planet carrier (PT2) of the second planetary gear set (RS2) is connected.

12. Multi-step transmission according to one of the preceding claims, characterized in that the sun gear (SR3) via the eighth shaft (8) and via the sixth switching element (B2) designed as a brake with the housing (1 1) is connectable.

13. Multi-speed transmission according to one of the preceding claims, characterized in that at least nine forward gears (G1 to G9) and at least one reverse gear (R) are switchable.

14. Multi-speed transmission according to one of the preceding claims, characterized in that the switching elements provided (K1, K2, K3, K4, B1, B2) are designed as frictional or positive switching elements.

15. Multi-speed transmission according to one of the preceding claims, characterized in that for switching the first forward gear (G1) designed as a clutch second switching element (K2), designed as a clutch fourth switching element (K4) and designed as a brake sixth switching element (B2) are closed, that for switching the second forward gear (G2), the first switching element (K1) designed as a clutch, the fourth shift element (K4) designed as a clutch and the sixth shift element (B2) designed as a brake are closed, that for shifting the third forward gear (G3) the first shift element (K1) designed as a clutch, the second shift element (K2) designed as a clutch and the fourth shift element (K4) designed as clutch are closed, that for shifting the fourth forward gear (G4) the second shift element designed as a clutch (K2), the third clutch Switching element (K3) and running as a clutch fourth switching element (K4) are closed, that for switching the fifth forward gear (G5) designed as a clutch first switching element (K1), designed as a clutch second switching element (K2) and running as a clutch third switching element (K3) are closed, that for switching the sixth forward gear (G6), the first switching element (K1) designed as a clutch, the third switching element (K3) designed as a clutch and the sixth switching element (B2) designed as a brake are closed for shifting the seventh forward gear (G7), the second shifting element (K2) designed as a clutch, the third shifting element (K3) designed as a clutch and the sixth shifting element (B2) designed as a brake are closed, that for shifting the eighth forward gear (G8) designed as a clutch third switching element (K3), designed as a brake fifth switching element (B1) and as Closed six sixth shift element (B2) are closed, that for switching the ninth forward gear (G9), the second switching element (K2) designed as a clutch, the third switching element (K3) designed as a clutch and the fifth switching element (B1) designed as a brake are closed in that, in order to shift the reverse gear (R), the second shifting element (K2) designed as a clutch, the fourth shifting element (K4) designed as a clutch and the fifth shifting element (B1) designed as a brake are closed.

1 6. Multi-step transmission according to one of the preceding claims, characterized in that for switching alternative fourth forward gears (M1, M2, M3) designed as a clutch third switching element (K3), designed as a clutch fourth switching element (K4) and as a brake executed fifth

Switching element (B1) are closed or the third switching element (K3) designed as a clutch, the fourth switching element (K4) designed as a clutch and the sixth shifting element (B2) designed as a brake are closed or the first shifting element (K1) designed as a clutch executed as a clutch third switching element (K3) and designed as a clutch fourth switching element (K4) are closed.