TRANSMISSION WITH A DIFFERENTIAL LOCKING UNIT

Abstract

A transmission with a differential locking unit which comprises an input shaft (10), first and second output shafts (11, 12), and first and second planetary gear sets (P1, P2). Torque introduced, via the input shaft (10), is converted and distributed to the two output shafts (11, 12) in a defined ratio, and development of a sum torque is prevented. The differential locking unit comprises an epicyclic gearing (P3) as well as a switching element (B 1). The epicyclic gearing (P3) has at least three connection shafts (3), a first connection shaft (WI) is rotationally fixed to a linking shaft (3), a second connection shaft (W2) is rotationally fixed to the second element (E21) of the first planetary gear set (PI), which is rotationally fixed to the first output shaft (11). A third connection shaft (W3) can be secured to a rotationally fixed component (GG) by the switching element (B 1).

Claims

1-14. (canceled)

15. A transmission with a differential locking unit, the transmission comprising: an input shaft (10), a first output shaft (11), a second output shaft (12), a first planetary gear set (P1), and a second planetary gear set (P2) connected to the first planetary gear set, wherein the first and the second planetary gear sets (P1, P2) each comprise multiple elements (E11, E21, E31, E12, E22, E32), the input shaft (10), the first and second output shafts (11, 12), the planetary gear sets (P1, P2) and elements thereof are arranged and are configured such that: a torque introduced via the input shaft (10) is converted and divided between the first and second output shafts (11, 12) in a defined ratio, and the generation of a sum torque is prevented, at least one element (E31) of the first planetary gear set (P1) is rotationally conjointly connected to another element (E12) of the second planetary gear set (P2) via a connecting shaft (3), and a further element (E22) of the second planetary gear set (P2) is fixed to a non-rotatable structural element (GG); the differential locking unit comprising an epicyclic transmission (P3) in a form of a planetary gear set or a planetary stage, and a shift element (B1), the epicyclic transmission (P3) has at least three connection shafts, an at least first connection shaft (W1) is rotationally conjointly connected to the connecting shaft (3), an at least second connection shaft (W2) is rotationally conjointly connected to the second element (E21) of the first planetary gear set (P1), and an at least third connection shaft (W3) is fixable to a non-rotatable structural element (GG) by the shift element (B1).

16. The transmission according to claim 15, wherein the shift element is designed as one of: a frictionally engaging brake, or a positively locking brake.

17. The transmission according to claim 15, wherein at least one further transmission (VÜ1), for increasing a rotational speed of the third connection shaft (W3), is provided between the epicyclic transmission (P3) and the shift element (B1).

18. The transmission according to claim 17, wherein the at least one further transmission (VÜ1) is one of: in a form of a planetary gear set (P4), or in a form of a spur gear stage (SRS).

19. The transmission according to claim 15, wherein a further transmission (VÜ2), in a form of a planetary gear set (P5) or a countershaft design, is provided for adapting a rotational speed of the input shaft (10).

20. The transmission according to claim 15, wherein a drive machine, in a form of an internal combustion engine or an electric machine, is provided for driving the input shaft (10).

21. The transmission according to claim 20, wherein the drive machine is in a form of an electric machine, and the electric machine is arranged coaxially or axially parallel.

22. The transmission according to claim 21, wherein the electric machine is arranged coaxially and the epicyclic transmission (P3) is either: arranged at least partially radially within a rotor of the electric machine, or arranged so as to be axially spaced apart from the electric machine.

23. The transmission according to claim 15, wherein the first output shaft (11) is guided through the epicyclic transmission (P3).

24. The transmission according to claim 15, wherein the input shaft (10) is guided through the epicyclic transmission (P3).

25. The transmission according to claim 15, wherein the epicyclic transmission (P3) is arranged axially adjacent to the first planetary gear set (P1).

26. The transmission according to claim 15, wherein the epicyclic transmission (P3) is arranged radially outside the first planetary gear set (P1).

27. A drivetrain having the transmission according to claim 15.

28. A vehicle having the drivetrain according to claim 27.

29. A vehicle having the transmission according to claim 15.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0104] Advantageous embodiments of the invention, which will be discussed below, are illustrated in the drawings. In the drawings:

[0105] FIGS. 1a-1e show a schematic view of a vehicle;

[0106] FIGS. 2-7 each show a schematic view of an exemplary transmission that can be used with a differential locking unit according to the invention in the vehicle from FIGS. 1a-1e;

[0107] FIGS. 8-13 each show a schematic view of an exemplary drivetrain having a transmission with a differential locking unit, as can be used in the vehicle from FIGS. 1a to 1e;

[0108] FIG. 14 shows the embodiment as per FIG. 3 in a sectional view;

[0109] FIGS. 15-18 show a schematic illustration of the functional principle of the invention;

[0110] FIG. 19 shows an overview of the static transmission ratios of the individual embodiments; and

[0111] FIGS. 20-34 show a schematic view of a respective drivetrain having a transmission with a differential locking unit in respectively preferred embodiments of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0112] FIGS. 1a to 1e each show a schematic view of a transmission G, having a differential locking unit which is not illustrated in any more detail, of a motor vehicle drivetrain 100 of a vehicle 1000 in the form of a passenger motor vehicle.

[0113] The drivetrain 100 as per FIG. 1a shows an electric drive which drives the rear axle A of the vehicle 1000. The drivetrain comprises a transmission G, which divides the drive torque of the electric machine EM between two output shafts 11 and 12. The transmission G and the electric machine are arranged in a common housing. The forward direction of travel is illustrated by arrow 99. As can also be seen in FIG. 1a, the transmission G and the electric machine EM are oriented transversely with respect to the direction of travel of the vehicle.

[0114] The drivetrain 100 as per FIG. 1b shows an internal combustion engine drive which drives the rear axle A of the vehicle 1000. The drivetrain comprises a transmission G, which divides the drive torque of the internal combustion engine VM between two output shafts 11 and 12, wherein a further transmission, for example an automatic transmission of the vehicle, is arranged between the transmission G and the internal combustion engine VM. The forward direction of travel is illustrated by arrow 99. As can also be seen in FIG. 1a, the transmission G and the internal combustion engine VM are oriented longitudinally with respect to the direction of travel of the vehicle.

[0115] The drivetrain 100 as per FIG. 1c shows an internal combustion engine drive which drives the rear axle A and the front axle B of the vehicle 1000. The drivetrain comprises a transmission G, which divides the drive torque of the internal combustion engine VM between the axles A and B, wherein a further transmission, for example an automatic transmission of the vehicle, is arranged between the transmission G and the internal combustion engine VM. The transmission G may then be connected via an output shaft 11 to an axle differential of the rear wheel axle A and via an output shaft 12 to an axle differential of the front axle B. The forward direction of travel is illustrated by arrow 99. As can also be seen in FIG. 1c, the transmission G and the internal combustion engine VM are oriented longitudinally with respect to the direction of travel of the vehicle.

[0116] The drivetrain 100 as per FIG. 1d shows an electric drive which drives the front axle B of the vehicle 1000, that is to say an electric front transverse drive. The drivetrain comprises a transmission G, which divides the drive torque of the electric machine EM between two output shafts 11 and 12. The transmission G and the electric machine are arranged in a common housing. The forward direction of travel is illustrated by arrow 99. As can also be seen in FIG. 1d, the transmission G and the electric machine EM are oriented transversely with respect to the direction of travel of the vehicle.

[0117] The drivetrain 100 as per FIG. 1e shows an electric all-wheel drive which drives the rear axle A and the front axle B of the vehicle 1000. This involves a transmission designed as a longitudinal transfer case. The drivetrain comprises a transmission G, which divides the drive torque of the electric machine EM between two output shafts 11 and 12. The output shaft 11 transmits the torque to the front axle B, whereas the output shaft 12 transmits the torque to the rear axle A. The respective torques are then in turn introduced into respective axle differentials. The transmission G and the electric machine are arranged in a common housing. The forward direction of travel is illustrated by arrow 99. As can also be seen in FIG. 1e, the transmission G and the electric machine EM are oriented transversely with respect to the direction of travel of the vehicle.

[0118] FIG. 2 shows a transmission G in a first exemplary embodiment. The transmission G comprises an input shaft 10, a first output shaft 11, a second output shaft 12, a first planetary gear set P1 and a second planetary gear set P2 which is connected to the first planetary gear set P1. In the present case, the planetary gear sets P1 and P2 are each designed as a minus planetary gear set. The planetary gear sets P1, P2 each comprise multiple elements E11, E21, E31, E12, E22, E32, wherein the first element E11 is a sun gear SO1, the second element E21 is a planet carrier PT1 and the third element E31 of the first planetary gear set P1 is a ring gear HO1. In the case of the second planetary gear set P2, the first element E12 is a sun gear SO2, the second element E22 is a planet gear carrier PT2 and the third element E32 is a ring gear HO2. The planet gear carriers PT1, PT2 each support multiple planet gears, which are illustrated but not designated. The planet gears mesh both with the respective radially inner sun gear and with the respective surrounding ring gear. The input shaft 10, the first output shaft 11 and the second output shaft 12 are arranged coaxially with respect to one another. The two planetary gear sets P1, P2 are likewise arranged coaxially with respect to one another.

[0119] In the present case, the input shaft 10 is connected rotationally conjointly to the first element E11. The first output shaft 11 is connected rotationally conjointly to the second element E21 of the first planetary gear set. The second output shaft 12 is connected rotationally conjointly to the third element E32 of the second planetary gear set. The third element E31 of the first planetary gear set P1 is connected rotationally conjointly to the first element E12 of the second planetary gear set P2, whereas the second element E22 of the second planetary gear set P2 is fixed to a non-rotatable structural element GG. The non-rotatable structural element GG is a transmission housing of the transmission G.

[0120] The third element E31, that is to say the ring gear HO1 of the first planetary gear set P1, and the first element E12, that is to say the sun gear SO2 of the second planetary gear set, form a common structural part, which in the present case is in the form of a connecting shaft or shaft 3.

[0121] As can be seen in FIG. 2, the input shaft 10, the first output shaft 11 and the second output shaft 12 are arranged coaxially with respect to one another. The two planetary gear sets P1, P2 are likewise arranged coaxially with respect to one another. According to this embodiment, the two planetary gear sets P1, P2 are arranged so as to be axially spaced apart from one another.

[0122] The input shaft 10 may be connected to a drive machine and thus introduce an input torque into the transmission G. That is to say, the input shaft 10 and output shafts 11, 12 rotate in the same direction. Through the connection of the two planetary gear sets P1, P2 to one another and the support of the second element E22 on the housing GG, the introduced input torque can be distributed between the two output shafts 11, 12. In this case, the transmission performs not only the function of a transmission gearing but additionally that of a differential gear. That is to say, the introduced torque is not only subjected to a speed ratio but is also distributed between various output shafts. In this embodiment, no reversal of the direction of rotation occurs.

[0123] FIG. 3 shows a further exemplary embodiment of the transmission G. By contrast to the embodiment as per FIG. 2, the embodiment as per FIG. 3 shows a radially nested arrangement of the two planetary gear sets P1, P2. Whereas the embodiment as per FIG. 2 proposes an extremely radially compact solution, the embodiment as per FIG. 3 makes possible an extremely axially compact transmission G. The first planetary gear set P1 in this case forms the radially inner planetary gear set. The second planetary gear set P2 forms the radially outer planetary gear set. The first planetary gear set P1 is accordingly situated radially within the second planetary gear set P2. In this embodiment, too, the connection of the first ring gear HO1 of the first planetary gear set P1 to the sun gear SO2 of the second planetary gear set is configured as a single structural part, which in the present case is likewise in the form of a shaft 3. It is likewise the case in this embodiment that no reversal of the direction of rotation occurs.

[0124] FIG. 4 shows a transmission G in a further exemplary embodiment. By contrast to FIG. 2, the first planetary gear set P1 is now configured as a plus planetary gear set. That is to say, the third element E31 of the first planetary gear set is configured as a planet gear carrier, which is connected rotationally conjointly to the first element E12 of the second planetary gear set, that is to say the sun gear SO2. The second element E21 is now configured as a ring gear HO1 and is connected rotationally conjointly to the first output shaft 11. The third element E31 of the first planetary gear set and the first element E12 of the second planetary gear set are in turn formed on the same structural part, which in the present case is in the form of a shaft 3. Reference is otherwise made to the statements relating to FIG. 2.

[0125] FIG. 5 shows a further exemplary embodiment of the transmission G. By contrast to the embodiment as per FIG. 2, it is now the case that both planetary gear sets P1, P2 are configured as plus planetary gear sets. Thus, the second element E21 is configured as a ring gear HO1 and is connected rotationally conjointly to the first output shaft 11. The third element E31 is now configured as a planet carrier PT1 and is connected rotationally conjointly to the first element E12, that is to say the sun gear SO2 of the second planetary gear set P2. The second element E22 of the second planetary gear set P2 is now configured as the ring gear HO2 and is fixed to the non-rotatable structural element GG. By contrast, the third element E32 of the second planetary gear set P2 is configured as a planet carrier PT2 and is connected rotationally conjointly to the second output shaft 12.

[0126] Thus, in the case of the two planetary gear sets P1, P2, the planet carrier and ring gear connections have been interchanged. Reference is otherwise made to the statements relating to FIG. 2.

[0127] FIG. 6 shows a transmission in a further exemplary embodiment. By contrast to the embodiment as per FIG. 2, the second planetary gear set P2 is now configured as a plus planetary gear set, whereas the first planetary gear set P1 remains unchanged. Thus, the ring gear HO2 of the second planetary gear set P2 is fixed to the housing GG. In addition, the planet carrier PT2 is connected rotationally conjointly to the second output shaft 12. The planet carrier and ring gear connections of the second planetary gear set have thus been interchanged. Reference is otherwise made to the statements relating to FIG. 2.

[0128] FIG. 7 shows a further exemplary embodiment of the transmission G. By contrast to the embodiment as per FIG. 6, the embodiment as per FIG. 7 provides radially nested planetary gear sets P1, P2. The planetary gear set situated radially at the inside is the first planetary gear set P1. The planetary gear set situated radially at the outside is the second planetary gear set P2. Reference is otherwise made to the statements relating to FIGS. 6 and 2.

[0129] FIG. 8 shows the transmission G in a further exemplary embodiment. This embodiment has the following differences in relation to the embodiment as per FIG. 2. Firstly, a drive machine in the form of an electric machine EM is provided. The electric machine EM comprises a stator S, which is fixed to the housing, and a rotor R. The rotor R of the electric machine EM is connected rotationally conjointly to the first element E11, that is to say the sun gear SO1 of the first planetary gear set. A further difference is that the second element E21 of the first planetary gear set is configured as a ring gear HO1 and is connected rotationally conjointly to the first output shaft 11. Furthermore, the third element E31 of the first planetary gear set P1 is configured as a planet carrier PT1 and is connected rotationally conjointly to the first element E12 of the second planetary gear set P2, which in the present case is configured as a ring gear HO2. The second element E22 of the second planetary gear set is furthermore configured as a planet carrier PT2 and is fixed to the housing GG. Accordingly, the third element E32 is configured as a sun gear SO2 and is connected rotationally conjointly to the second output shaft. In this exemplary embodiment, a reversal of the direction of rotation of the input rotational speed occurs. Nesting of the planetary gear sets P1, P2 is not possible in this embodiment.

[0130] In other words, the torque continues to be introduced via the sun gear SO1 of the first planetary gear set P1, whereas the output is ensured via the ring gear HO1. By contrast to the situation in FIG. 2, the planet carrier of the first planetary gear set P1 is now connected rotationally conjointly to the ring gear HO2 of the second planetary gear set. By contrast to the embodiment as per FIG. 2, the output of the second planetary gear set accordingly takes place via the sun gear SO2.

[0131] FIG. 9 shows a further exemplary embodiment of the transmission G. The embodiment has the following differences in relation to the embodiment as per FIG. 2. Firstly, a drive machine in the form of an electric machine EM is provided, which has a stator S, which is fixed to the housing, and a rotor R. The rotor R is connected rotationally conjointly to the input shaft 10, which in turn is connected to the first element E11, which in the present case is configured as a ring gear HO1, of the first planetary gear set P1. The first output shaft 11 is in the present case connected to the second element E21, which in the present case is in the form of a planet carrier PT2, of the first planetary gear set P1. The third element E31 of the first planetary gear set P1, which in the present case is configured as a sun gear SO1, is connected rotationally conjointly to the first element E12, that is to say the sun gear SO2 of the second planetary gear set P2. The other elements of the second planetary gear set remain unchanged.

[0132] By contrast to the embodiment as per FIG. 2, it is the case in the embodiment as per FIG. 9 that the introduction of the torque takes place via the ring gear HO1 of the first planetary gear set P1, whereas the output of the first planetary gear set P1 continues to be realized via the planet carrier PT1. By contrast to FIG. 2, the two planetary gear sets P1, P2 are connected via a common sun gear, which in the present case is in the form of a shaft 3.

[0133] FIG. 9a shows a specific embodiment of the transmission G for the drivetrain from FIG. 1c. Output 12 transmits the torque to the rear axle A. Output 11 transmits the torque to the front axle B. As can be clearly seen, the output shafts 11, 12 are arranged axially parallel with respect to one another—and not coaxially with respect to one another. The second output shaft 12 of the second planetary gear set P2 meshes with an intermediate toothed gear ZZ, which in turn is connected to a shaft which in turn introduces the torque into a rear-axle differential (not illustrated).

[0134] FIG. 10 shows a drivetrain 100 of a vehicle with a transmission in an exemplary embodiment, wherein a transmission gearing in the form of a planetary gear P33 is additionally connected upstream of the transmission G.

[0135] The transmission G is the embodiment as per FIG. 3, to which reference is hereby made. The planetary gear set P33 is configured as a minus planetary gear set and has a first element E133, which is configured as a sun gear, a second element E233, which is configured as a planet carrier, and a third element E333, which in the present case is configured as a ring gear HO33. The second element E233 of the additional planetary gear set P33 is connected rotationally conjointly to the input shaft 10 of the transmission G.

[0136] Furthermore, a shift element SE is assigned to the planetary transmission P33. The shift element SE is configured to fix the third element E333 to the non-rotatable structural element GG. Furthermore, the shift element SE is configured to, in a second shift position, connect the third element E333 to the first element E133 of the planetary gear set P33, that is to say to place these in a block state. If a planetary gear set is in a block state, the speed ratio is always 1, regardless of the number of teeth. In other words, the planetary gear set revolves as a block. In a third shift position, the third element E333 is not fixed to the housing, nor is the planetary gear set P33 in a block state. The shift element SE is in this case present in a neutral shift position. The first shift position of the shift element SE is denoted by the reference designation G1, which at the same time represents a first gear ratio stage. The second shift position is denoted by the reference designation G2, which at the same time represents a second gear ratio stage. The first element E13 of the planetary gear set P3 is connected via an input shaft 14 to a drive machine (not illustrated). If the shift element SE is in its neutral position, the drive torque introduced into the transmission gearing P33 is not transmitted to the input shaft 10 of the transmission G.

[0137] As can also be clearly seen from FIG. 10, the transmission gearing P33 is arranged coaxially with respect to the input shaft 10 and with respect to the output shafts 11, 12. In addition, it can be clearly seen how the first output shaft 11 is guided through the input shaft 10 designed as a hollow shaft and, over the further course, through the further shaft 14 designed as a hollow shaft. The two output shafts 11, 12 are each connected to a drive wheel 20. Vibration dampers 15 are provided in order to absorb the vibrations of the vehicle.

[0138] FIG. 11 shows a drivetrain of a vehicle having a transmission in a further exemplary embodiment. The transmission G is the preferred embodiment as per FIG. 2, to which reference is made. By contrast to FIG. 10, no transmission gearing is connected upstream in the embodiment as per FIG. 11. The drive machine is configured as an electric machine EM. The electric machine EM has a stator S, which is fixed to the housing, and a rotor R. The rotor R is connected rotationally conjointly to the input shaft 10. As can be clearly seen, the electric machine EM is arranged coaxially with respect to the input shaft 10 and with respect to the output shafts 11, 12. In addition, said electric machine is thus arranged coaxially with respect to the planetary gear sets P1, P2. The input shaft 10 is configured as a hollow shaft through which the first output shaft 11 is guided. Reference is otherwise made to the statements relating to FIG. 10.

[0139] FIG. 12 shows a further drivetrain 100 with a transmission G in an exemplary embodiment. By contrast to the embodiment as per FIG. 11, the planetary gear sets P1, P2 are arranged not axially adjacent to one another but radially one above the other, that is to say in nested fashion. The transmission G is thus the preferred embodiment from FIG. 3. Reference is otherwise made to the statements relating to FIG. 11 and FIG. 3.

[0140] FIG. 13 shows a drivetrain 100 in a further exemplary embodiment. This embodiment is similar to the embodiment as per FIG. 11, wherein, by contrast thereto, the electric machine EM is arranged not coaxially but axially parallel with respect to the transmission G. A connection is realized here via a spur gear stage SRS, which is composed of a first spur gear SR1 and a second spur gear SR2. The first spur gear SR1 is in this case connected rotationally conjointly to the input shaft 10. The spur gear SR1 is then in tooth meshing engagement with the spur gear SR2, which is located rotationally conjointly on an input shaft EW of the electric machine EM, which input shaft, within the electric machine EM, produces the connection to the rotor (not illustrated in any more detail here) of the electric machine EM. Otherwise, the embodiment as per FIG. 13 corresponds to the embodiment as per FIG. 11, such that reference is made to the description given with regard thereto.

[0141] FIG. 14 shows the embodiment of the transmission Gas per FIG. 3 in a sectional view. The shaft situated in the center is the output shaft 11. In this drawing, the input shaft 10 coincides with the sun gear of P1, that is to say, in other words, the input shaft 10 is connected to a sun gear of the first planetary gear set P1. The sun gear of the first planetary gear set P1 is in turn in tooth meshing engagement with planet gears of the first planetary gear set P1. The planet gears of the first planetary gear set P1 in turn mesh with the surrounding ring gear of the first planetary gear set P1, wherein the ring gear simultaneously forms the sun gear of the second planetary gear set P2. The sun gear of the second planetary gear set P2 is in turn in tooth meshing engagement with planet gears of the second planetary gear set P2. The planet gears of the second planetary gear set P2 are in turn in tooth meshing engagement with the ring gear, which surrounds the planet gears, of the second planetary gear set P2.

[0142] The following FIGS. 15 to 17 show the introduction of force and force support configurations of the transmission according to this invention in relation to the prior art, such as DE 10 2011 079 975 A1. The prior art is compared with the preferred embodiment with two minus planetary transmissions, as have been described inter alia in FIGS. 2 and 3. However, this consideration also applies analogously to the other embodiments.

[0143] The following generally applies to FIGS. 15 to 17:

[0144] At the first planetary gear set P1, the torque of the input shaft 10 is converted into the output torque for the first output 11. The third element E31 of the first planetary gear set P1 (which is at the same time the first element E12 of the second planetary gear set P2) is driven backward by its reaction moment. The backward movement of the third element E31 is permitted, such that a proportion of the mechanical drive power (preferably 50% in the case of the transverse differential and straight-ahead travel) is conducted through the first planetary set P1 into the second planetary set.

[0145] Furthermore, the backward rotation causes the speed ratio with respect to the first output (11) to be increased (static transmission ratio i0=−3 would allow only a speed ratio of i=4 in the case of a fixed ring gear).

[0146] In the second planetary set P2, the direction of rotation (backward) introduced at the first element (E12) is, with the aid of a housing support (E22), reversed (forward) into the output movement of the second output (12). Here, the torque introduced into the second planetary set P2 and the torque conducted out to the second output (12) are summed to give the housing support torque. Here, the second planetary set P2 transmits only that proportion of the mechanical power that is conducted to the second output (12) (typically 50%). Only a proportion of the power is applied to the second planetary set P2, such that the overall efficiency is positively influenced.

[0147] In the prior art, a torque conversion usually takes place with the aid of a housing support. The reaction moment of the transmission gearing is in this case conducted directly into the housing and does not serve to generate the second output torque. The result is that a transmission must firstly be configured for the sum torque of the two output shafts (generally double the torque). A separate differential transmission is then required to divide this sum torque, which is not required in this form at any location, into two output torques again.

[0148] The individual FIGS. 15 to 18 specifically show the following:

[0149] FIG. 15 schematically shows the first planetary gear set P1 of the transmission G (right) and a first stage of the spur gear differential from the prior art (left). The introduction of force from the planet gears to the sun gear takes place in parallel via 3 static, that is to say fixed, tooth meshing engagement points. The output to the first output shaft takes place via the sun gear.

[0150] By contrast to this, the introduction of force according to the preferred embodiment takes place in parallel via eight moving, that is to say rotating, tooth meshing engagement points. There are four tooth meshing engagement points between sun gear SO1 and four planet gears. Four further tooth meshing engagement points act between a respective planet gear and the ring gear HO1 (not illustrated). The output to the first output shaft 11 takes place via the planet gear carrier PT1. The technical effect lies in the significantly lower tooth forces that act on the first planetary gear set.

[0151] FIG. 16 schematically shows the second planetary gear set P2 of the transmission G (right) and a second stage of the stepped planet from the prior art (left). The introduction of force from the planet gears to the sun gear takes place in parallel via 3 static, that is to say fixed, tooth meshing engagement points. The output to the second output shaft takes place via the sun gear.

[0152] By contrast to this, the introduction of force into the second planetary gear set P2 according to the preferred embodiment takes place in parallel via 6 moving, that is to say rotating, tooth meshing engagement points. The six tooth meshing engagement points act in each case between one of the six planet gears and the ring gear HO2. The fixed planet carrier PT2, which carries the six planet gears and the sun gear SO2, are not illustrated. The output to the second output shaft 12 takes place via the ring gear HO2. The technical effect lies in the significantly lower tooth forces that act on the second planetary gear set owing to the larger effective diameter and owing to the larger possible number of planets.

[0153] FIG. 17 schematically shows the introduction of the supporting torque into the housing. The introduction of force in the case of the stepped planet according to the prior art (left) takes place into a fixed ring gear via 3 parallel tooth meshing engagement points.

[0154] The introduction of force according to the preferred embodiment takes place into the fixed planet carrier PT2 via 12 parallel tooth meshing engagement points. Six tooth meshing engagement points act between the sun gear SO2 and the six planet gears of the second planetary gear set. The six other tooth meshing engagement points act between each planet gear of the second planetary gear set and the ring gear HO2. The technical effect lies in the significantly lower tooth forces that act on the second planet carrier PT2.

[0155] FIG. 18 shows the principle illustrated in more detail in FIGS. 15 to 17 in a further view. The figure symbolically illustrates the torques in terms of magnitude on their path through the transmission. Directions of rotation are not apparent from this.

[0156] The stepped planetary set according to the prior art (left) generates the full output torque, that is to say the sum torque of both wheels, from one input torque M.sub.an. The differential divides this high moment into two half wheel moments M.sub.an1 and M.sub.an2.

[0157] The greatest torque in the gear set according to the invention (right) corresponds to the output torque of a single gear. Only the housing support has a high torque factor in accordance with physical principles.

[0158] FIG. 19 gives an overview of the calculation rule for the static transmission ratio of the individual embodiments. These each give rise, if transmission losses are neglected, to an output torque of equal magnitude and with the same sign at both output shafts (11, 12). i.sub.01 denotes the static transmission ratio of the second planetary gear set P1. i.sub.02 denotes the static transmission ratio of the second planetary gear set P2. One of the planetary gear set configurations with corresponding static transmission ratio may be selected depending on the use of the transmission.

[0159] FIG. 20 shows a drivetrain 100 of a vehicle having a transmission G with a differential locking unit in a preferred embodiment. The drivetrain 100 is based on the drivetrain known from FIG. 10, wherein, by contrast thereto, no additional planetary transmission P33 is provided in order to increase the rotational speed of the drive machine. The planetary gear sets P1, P2 accordingly constitute the radially stacked arrangement of two minus planetary gear sets, which is likewise known from FIG. 3. This arrangement is particularly highly suitable for the provision of a differential locking unit, because the radially stacked arrangement saves axial installation space, which can be used for the differential locking unit.

[0160] The differential locking unit comprises an epicyclic transmission (P3) with at least three connection shafts. The epicyclic transmission P3 is in the form of a third planetary gear set, wherein the third planetary gear set is designed as a minus planetary transmission with multiple elements.

[0161] A first connection shaft W1 forms a first element E13 of the third planetary gear set, which in the present case is configured as a sun gear SO3. A second connection shaft W2 forms a third element E33 of the third planetary gear set P3, which in the present case is configured as a ring gear HO3. A third connection shaft W3 forms a second element E23 of the third planetary gear set, which in the present case is configured as a planet carrier PT3.

[0162] The sun gear SO3 of the third planetary gear set P3 is connected rotationally conjointly to the connecting shaft 3. The ring gear HO3 of the third planetary gear set P3 is connected rotationally conjointly to an element of the first planetary gear set P1, in the present case configured as a planet carrier PT1. The first planet carrier PT1 is in turn connected rotationally conjointly to the first output shaft 11. The planet carrier PT3 of the third planetary gear set P3 is connectable by means of a shift element designed as a brake B1 to a non-rotatable structural part GG.

[0163] In other words, the epicyclic transmission P3 is configured as a 3-shaft transmission, wherein the planet carrier PT3 is fixable to the housing GG by means of the brake B1, the ring gear HO3 is connected rotationally conjointly to the output 11 of the first planetary gear set P1, and the sun gear SO3 is connected rotationally conjointly to the connecting shaft 3, that is to say that shaft 3 which connects the two planetary gear sets P1 and P2 to one another. The connecting shaft 3 is formed by the ring gear HO1 of the first planetary gear set P1 and the sun gear SO2 of the second planetary gear set P2. The locking action is achieved when the brake B1 is actuated, that is to say the third connection shaft W3 is fixed to the housing.

[0164] The third planetary gear set P3 and the electric machine EM are arranged coaxially with respect to the two output shafts 11, 12 and the input shaft 10 of the transmission G. As can be clearly seen, the third planetary gear set P3 is arranged axially spaced apart from the radially stacked planetary gear sets P1, P2.

[0165] The static transmission ratio may for example be configured as follows:

i.sub.0_P1=−3.00

i.sub.0_P2=−1.33

i.sub.0_P3=−1.33

[0166] During straight-ahead travel, the third connection shaft W3 has the rotational speed zero. When the brake B1 is closed, synchronism of the two output shafts is enforced, which results in the locking action.

[0167] FIG. 21 shows a drivetrain 100 of a vehicle having a transmission G with a differential locking unit in a further preferred embodiment. By contrast to FIG. 20, the third planetary gear set P3 is designed as a plus planetary gear set, wherein the planet carrier and ring gear connections have been interchanged and the magnitude of the static transmission ratio has been increased by one. A functionally identical transmission is thus realized.

[0168] The sun gear SO3 and thus the first connection shaft W1 remain connected to the connecting shaft 3. The second connection shaft W2 is still connected to the output of the first planetary gear set P1, wherein the shaft W2 is now formed by the planet carrier PT3. The third connection shaft W3 can still be fixed by means of the brake B1, wherein the shaft W3 now forms the ring gear HO3.

[0169] The locking action is achieved when the ring gear HO3 is fixed to the housing GG. The static transmission ratio may for example be configured as follows:

i.sub.0_P1=−3.00

i.sub.0_P2=−1.33

i.sub.0_P3=+2.33

[0170] During straight-ahead travel, the third connection shaft W3 has the rotational speed zero. When the brake B1 is closed, synchronism of the two output shafts is enforced, which results in the locking action.

[0171] Otherwise, the embodiment as per FIG. 21 corresponds to the embodiment as per FIG. 20, such that reference is made to the description given with regard thereto.

[0172] FIG. 22 shows a drivetrain 100 of a vehicle having a transmission G with a differential locking unit in a preferred embodiment. By contrast to FIG. 20, the third planetary gear set P3 is designed as a plus planetary gear set, wherein the connections of the elements and the required static transmission ratio have been adapted.

[0173] The second connection shaft W2 of the third planetary gear set P3 is accordingly configured as a sun gear SO3 and is connected to the output 11. The first connection shaft of the third planetary gear set P3 is configured as a planet carrier PT3 and is connected rotationally conjointly to the connecting shaft 3. The third connection shaft of the third planetary gear set P3 is in the form of a ring gear and is connectable to the housing GG by means of the brake B1. The static transmission ratio may for example be configured as follows:

i.sub.0_P1=−3.00

i.sub.0_P2=−1.33

i.sub.0_P3=+1.75

[0174] During straight-ahead travel, the third connection shaft W3 has the rotational speed zero. When the brake B1 is closed, synchronism of the two output shafts is enforced, which results in the locking action.

[0175] Otherwise, the embodiment as per FIG. 22 corresponds to the embodiment as per FIG. 21 or 20, such that reference is made to the description given with regard thereto.

[0176] FIG. 23 shows a drivetrain 100 of a vehicle having a transmission G with a differential locking unit in a preferred embodiment. By contrast to FIG. 22, the epicyclic transmission is in the present case designed as a stepped planet with multiple sun gear connections. For this purpose, two fixed gears of different sizes and mounted on the planet carrier PT3 are in tooth meshing engagement with a respective sun gear. This thus constitutes a planetary stage with two sun gear connections. A relatively large first fixed gear Z1 meshes with a first sun gear SO3-1. A relatively small second fixed gear Z2 meshes with a second sun gear SO3-2.

[0177] The first connection shaft W1 is configured as a planet carrier PT3 and is connected rotationally conjointly to the connecting shaft 3.

[0178] The second connection shaft W2 is configured as the first sun gear SO3-1 and is connected rotationally conjointly to the planet carrier PT1 and thus to the output 11. The third connection shaft W3 is now not in the form of the ring gear HO3 but is configured as the second sun gear SO3-2 and is fixable to the housing GG by means of the brake B1.

[0179] The static transmission ratio may for example be configured as follows:

i.sub.0_P1=−3.00

i.sub.0_P2=−1.33

i.sub.0_P3=+1.75

[0180] During straight-ahead travel, the third connection shaft W3 has the rotational speed zero. When the brake B1 is closed, synchronism of the two output shafts is enforced, which results in the locking action.

[0181] Otherwise, the embodiment as per FIG. 23 corresponds to the embodiment as per FIG. 22, such that reference is made to the description given with regard thereto.

[0182] FIG. 24 shows a drivetrain 100 of a vehicle having a transmission G with a differential locking unit in a preferred embodiment. By contrast to FIG. 23, the connections of the third planetary gear set are implemented not by means of two sun gears but by means of two ring gears HO3-1 and HO3-2. The smaller of the two fixed gears of the planetary stage is in tooth meshing engagement with the ring gear HO3-1, while the larger of the two fixed gears is in tooth meshing engagement with the ring gear HO3-2. This is also referred to as a planetary stage with two ring gear connections. The first connection shaft of the third planetary gear set P3 is still configured as a planet carrier PT3 and connected rotationally conjointly to the connecting shaft 3.

[0183] The second connection shaft W2 of the third planetary gear set P3 is in the form of the ring gear HO3-2 and is connected rotationally conjointly to the planet carrier PT1 and thus to the output 11. The third connection shaft W3 of the third planetary gear set P3 is accordingly configured as a ring gear HO3-1 and is fixable to the housing GG by means of the brake B1. The static transmission ratio may for example be configured as follows:

i.sub.0_P1=−3.00

i.sub.0_P2=−1.33

i.sub.0_P3=1.75

[0184] During straight-ahead travel, the third connection shaft W3 has the rotational speed zero. When the brake B1 is closed, synchronism of the two output shafts is enforced, which results in the locking action.

[0185] Otherwise, the embodiment as per FIG. 24 corresponds to the embodiment as per FIG. 23, such that reference is made to the description given with regard thereto.

[0186] FIG. 25 shows a drivetrain 100 of a vehicle having a transmission G with a differential locking unit in a preferred embodiment. By contrast to FIG. 21, the epicyclic transmission unit P3 is designed as a plus planetary gear set with a stepped planet design.

[0187] Here, two fixed gears of different sizes and mounted on the planet carrier PT3 are in tooth meshing engagement with a respective sun gear. This thus constitutes a planetary stage with two sun gear connections. A relatively small first fixed gear meshes with a first sun gear SO3-1. A relatively large second fixed gear meshes with a second sun gear SO3-2.

[0188] The second connection shaft W2 of the third planetary gear set P3 is configured as the planet carrier PT3 and is connected to the output 11. The first connection shaft W1 of the third planetary gear set P3 is configured as a sun gear SO3-2 and is connected rotationally conjointly to the connecting shaft 3. The third connection shaft W3 of the third planetary gear set P3 is in the form of sun gear SO3-1 and is fixable to the housing GG by means of the brake B1. The static transmission ratio may for example be configured as follows:

i.sub.0_P1=−3.00

i.sub.0_P2=−1.33

i.sub.0_P3=+2.33

[0189] During straight-ahead travel, the third connection shaft W3 has the rotational speed zero. When the brake B1 is closed, synchronism of the two output shafts is enforced, which results in the locking action.

[0190] Otherwise, the embodiment as per FIG. 25 corresponds to the embodiment as per FIG. 21, such that reference is made to the description given with regard thereto.

[0191] FIG. 26 shows a drivetrain 100 of a vehicle having a transmission G with a differential locking unit in a preferred embodiment. By contrast to FIG. 25, the connection of the third planetary gear set P3 is implemented not by means of sun gears but by means of two ring gears HO3-1 and HO3-2. Here, two fixed gears of different sizes and mounted on the planet carrier PT3 are in tooth meshing engagement with a respective ring gear. This thus constitutes a planetary stage with two ring gear connections. A relatively large first fixed gear meshes with a first ring gear HO3-1. A relatively small second fixed gear meshes with a second ring gear HO3-2.

[0192] The second connection shaft of the third planetary gear set P3 is configured as the planet carrier PT3 and is connected to the output 11. The first connection shaft W1 of the third planetary gear set P3 is configured as a ring gear HO3-1 and is connected rotationally conjointly to the connecting shaft 3. The third connection shaft W3 of the third planetary gear set P3 is in the form of ring gear HO3-2 and is fixable to the housing GG by means of the brake B1. The static transmission ratio may for example be configured as follows:

i.sub.0_P1=−3.00

i.sub.0_P2=−1.33

i.sub.0_P3=+2.33

[0193] During straight-ahead travel, the third connection shaft W3 has the rotational speed zero. When the brake B1 is closed, synchronism of the two output shafts is enforced, which results in the locking action.

[0194] Otherwise, the embodiment as per FIG. 26 corresponds to the embodiment as per FIG. 25, such that reference is made to the description given with regard thereto.

[0195] The advantages of the differential locking unit or the transmission G with the differential locking unit according to the embodiments of FIGS. 20 to 26 lie in a compact design and good efficiency. The differential locking unit is of technically low complexity in terms of construction and is thus inexpensive. Furthermore, the potential can be fully exploited by way of the connection of the planetary transmission P3 to the connecting shaft 3.

[0196] The potential of the application of force to the connecting shaft 3 lies in the fact that the planetary gear set P3 can be of simpler design owing to the different directions of rotation. If this were to act between two shafts running in synchronism, as in the prior art, the outlay complexity would be greater. Furthermore, in a conventional differential, the left-hand and right-hand side shafts are generally difficult to bind owing to the drive action on the differential cage.

[0197] FIGS. 27 and 28 show further preferred variants based on the embodiment according to FIG. 20. In these variants, the second and third planetary gear sets P2, P3 are arranged radially outside the first planetary gear set P1. The third planetary gear set P3 is arranged axially spaced from the second planetary gear set P2. The connections are maintained here. The third connection shaft W3 is fixable to the housing GG by means of the brake B1. The embodiments of FIGS. 27 to 29 are more complex in terms of construction than the embodiments of FIGS. 20 to 26.

[0198] The variant according to FIG. 27 shows an axial sequence as follows: second planetary gear set P2, third planetary gear set P3, electric machine EM.

[0199] The variant according to FIG. 28 shows an axial sequence in which the two planetary gear sets P2, P3 have been interchanged. The third connection shaft W3 is connectable by means of the brake B1 to the planet carrier PT2, which is permanently fixed to the housing GG, of the second planetary gear set P2.

[0200] Based on the embodiment according to FIG. 20, FIG. 29 shows the shift element B1 as a positively locking shift element in the form of a claw-type brake or claw. The design of the brake as a claw is possible in all of the differential locking units described above. The advantage of a claw is that it can be engaged with little actuation energy. This can for example be performed manually. Furthermore, a claw requires little installation space.

[0201] It is conceivable for an additional speed ratio to be applied both to the rotational speed of the third connection shaft W3 and/or to that of the input shaft 10, that is to say for the speed ratio imparted by the differential locking unit to be additionally increased. Irrespective of the specific design as a minus planetary gear set, plus planetary gear set or planetary stage, the third connection shaft W3 may have a speed ratio applied thereto by means of a further planetary transmission or by means of a spur gear stage.

[0202] Based on the embodiment according to FIG. 20, FIG. 30 shows an application of a speed ratio to the third connection shaft W3 by means of a further transmission VÜ1 in the form of a fourth planetary gear set P4. The fourth planetary gear set P4 has three elements, namely a first element E14, a second element E24 and a third element E34.

[0203] The first element E14 is designed as a sun gear SO4. The second element E24 is designed as a planet carrier PT4. The third element is designed as a ring gear HO4.

[0204] The ring gear HO4 is permanently fixed. The planet carrier PT4 is connected rotationally conjointly to the third connection shaft W3. The sun gear SO4 is fixable to the housing by means of the brake B1.

[0205] By contrast to the embodiment according to FIG. 30, FIG. 31 shows a spur gear stage SRS as a further transmission VÜ1. The spur gear stage SRS comprises a first spur gear SR1 and a second spur gear SR2, wherein the two spur gears are in tooth meshing engagement with one another. The smaller of the two spur gears SR1 is fixable to the housing GG by means of the brake B1. The larger of the two spur gears SR2 is connected rotationally conjointly to the third connection shaft W3.

[0206] FIG. 32 shows the embodiment according to FIG. 22 with a fourth planetary gear set P4 for applying a speed ratio to the third connection shaft W3.

[0207] The fourth planetary gear set P4 has three elements, namely a first element E14, a second element E24 and a third element E34.

[0208] The first element E14 is designed as a sun gear SO4. The second element E24 is designed as a planet carrier PT4. The third element is designed as a ring gear HO4.

[0209] The ring gear HO4 is permanently fixed. The planet carrier PT4 is connected rotationally conjointly to the third connection shaft W3. The sun gear SO4 is fixable to the housing by means of the brake B1.

[0210] The application of a speed ratio to the third shaft is also possible in the same way in the case of the differential locking unit according to FIG. 21.

[0211] FIG. 33 shows the embodiment according to FIG. 23 with a fourth planetary gear set P4 for applying a speed ratio to the third connection shaft W3.

[0212] The fourth planetary gear set P4 has three elements, namely a first element E14, a second element E24 and a third element E34.

[0213] The first element E14 is designed as a sun gear SO4. The second element E24 is designed as a planet carrier PT4. The third element is designed as a ring gear HO4.

[0214] The ring gear HO4 is permanently fixed. The planet carrier PT4 is connected rotationally conjointly to the third connection shaft W3. The sun gear SO4 is fixable to the housing by means of the brake B1.

[0215] The application of a speed ratio to the third shaft is also possible in the case of the other differential locking units of stepped-planet design, that is to say in particular in the case of the designs according to FIGS. 25 and 26. The third connection shaft W3 in the embodiment according to FIG. 24 is possible but cumbersome.

[0216] FIG. 34 shows, by way of example, the application of a speed ratio to the input shaft 10 based on the embodiment known from FIG. 20. The embodiment comprises a further transmission VÜ2 in the form of a fifth planetary gear set P5. The fifth planetary gear set P5 has three elements, namely a first element E15, a second element E25 and a third element E35.

[0217] The first element E15 is designed as a sun gear SO5. The second element E25 is designed as a planet carrier PT5. The third element E35 is designed as a ring gear HO5.

[0218] The ring gear HO5 is permanently fixed. The planet carrier PT5 is connected rotationally conjointly to the input shaft 10. The sun gear SO5 is permanently connected to the drive machine. According to this embodiment, the sun gear SO5 is connected to the rotor R of the electric machine EM.

[0219] In the illustrated FIGS. 20 to 34, the transmission gearings P4, P5, SRS are illustrated as being integrated into the rotor R. However, it is equally preferred to arrange the elements axially adjacent to one another. Axially parallel arrangements of the electric machines are additionally conceivable. All of the solutions in FIGS. 20 to 34 have in common the fact that the epicyclic transmission P3 engages firstly on the output 11 of the first planetary gear set P1 and secondly on the connecting shaft 3 between the two planetary gear sets P1 and P2.

[0220] The invention has been described and explained comprehensively with reference to the drawings and the description. The description and explanation are to be understood as examples and not as being limiting. The invention is not limited to the disclosed embodiments. Other embodiments or variations will become apparent to a person skilled in the art from the use of the present invention and from a close analysis of the drawings, the disclosure and the following claims.

[0221] In the patent claims, the words “comprising” and “having” do not exclude the presence of further elements or steps. The indefinite article “a” or “an” does not exclude the presence of a multiplicity. A single element or a single unit may perform the functions of several of the units mentioned in the patent claims. The mere mention of certain measures in several different dependent patent claims should not be understood to mean that a combination of these measures cannot likewise be advantageously used.

REFERENCE DESIGNATIONS

[0222] G Transmission [0223] GG Non-rotatable structural element, housing [0224] P1 First planetary gear set [0225] P2 Second planetary gear set [0226] P33 Additional planetary gear set [0227] P3 Third planetary gear set [0228] P4 Fourth planetary gear set [0229] P5 Fifth planetary gear set [0230] E1(x) First element of x-th planetary gear set [0231] E2(x) Second element of x-th planetary gear set [0232] E3(x) Third element of x-th planetary gear set [0233] SO(x) Sun gear of x-th planetary gear set [0234] PT(x) Planet carrier of x-th planetary gear set [0235] HO(x) Ring gear of x-th planetary gear set [0236] E133 First element of the additional planetary transmission P33 [0237] E233 Second element of the additional planetary transmission P33 [0238] E333 Third element of the additional planetary transmission P33 [0239] EM Electric machine [0240] S Stator [0241] R Rotor [0242] EW Input shaft, electric machine [0243] VÜ1 Further transmission [0244] VÜ2 Further transmission [0245] SRS Spur gear stage [0246] SR1 First spur gear [0247] SR2 Second spur gear [0248] SE Shift element [0249] G1 First shift position, first gear ratio stage [0250] G2 Second shift position, second gear ratio stage [0251] N Neutral position [0252] VM Internal combustion engine [0253] A Axle of the vehicle, rear [0254] B Axle of the vehicle, front [0255] T Transmission, automatic transmission [0256] 3 Shaft, connecting shaft [0257] 10 Input shaft [0258] 11 First output shaft [0259] 12 Second output shaft [0260] 15 Dampers [0261] 20 Wheels [0262] 99 Direction of travel, forward [0263] 100 Drivetrain [0264] 1000 Vehicle