Planetary Multi-Stage Transmission

Abstract

Proposed is a multi-stage transmission in planetary design in a housing (9) for a vehicle comprising at least one electric motor (EM) and comprising three planetary gear sets (RS1, RS2, RS3), wherein a drive (An) can be connected by means of a shift element (K0) to a first shaft (1), and an output (Ab) is connected to a second shaft (2), wherein there are provided four additional shafts (3, 4, 5, 6) and at least five shift elements (B1, K1, K2, K3, K4), through the actuation of which at least eight forward gears (G1, G2, G3, G4, G5, G6, G7, G8) can be implemented. According to the invention, the first element of the first planetary gear set (RS1) is connected to the housing (9), wherein the first shaft (1) is permanently connected to the second element of the first planetary gear set (RS1); wherein the rotor (10) of the electric motor (EM) is connected to the third element of the first planetary gear set (RS1); and wherein the third element of the first planetary gear set (RS1) can be connected by means of at least one shift element (K3, K4) to at least one element of at least one additional planetary gear set (RS2, RS3).

Claims

1. Multi-stage transmission in planetary design in a housing (9) for a vehicle comprising at least one electric motor (EM) and comprising three planetary gear sets (RS1, RS2, RS3), wherein a drive (An) can be connected by means of at least one shift element (K0) to a first shaft (1), and an output (Ab) is connected to a second shaft (2), wherein there are provided four additional shafts (3, 4, 5, 6) and at least five additional shift elements (B1, K1, K2, K3, K4), through the actuation of which at least eight forward gears (G1, G2, G3, G4, G5, G6, G7, G8) can be implemented, characterized in that the first element of the first planetary gear set (RS1) is connected to the housing (9); that the first shaft (1) is permanently connected to the second element of the first planetary gear set (RS1); that the rotor (10) of the electric motor (EM) is connected to the third element of the first planetary gear set (RS1); and that the third element of the first planetary gear set (RS1) can be connected by means of at least one shift element (K3, K4) to at least one element of at least one additional planetary gear set (RS2, RS3).

2-10. (canceled)

Description

[0021] The present invention is explained in more detail below with reference to the drawings. In the drawings:

[0022] FIG. 1 shows a schematic view of a first design variant of the invented multi-stage transmission in planetary design with a coaxial drive and output;

[0023] FIG. 2 shows a schematic view of an alternative embodiment of the first design variant;

[0024] FIG. 3 shows schematic view of a second design variant of the multi-stage transmission with a lateral output;

[0025] FIG. 4 shows a schematic view of the first design variant with a first planetary gear set designed as a plus planetary gear set;

[0026] FIG. 5 shows a schematic view of the first design variant with a second planetary gear set designed as a plus planetary gear set;

[0027] FIG. 6 shows a schematic view of the first design variant with a third planetary gear set designed as a plus planetary gear set;

[0028] FIG. 7 shows a schematic view of the first design variant with nested second and third planetary gear sets;

[0029] FIG. 8 shows a schematic view of the second design variant with nested second and third planetary gear sets;

[0030] FIG. 9 shows an additional schematic view of the second design variant with nested second and third planetary gear sets; and

[0031] FIG. 10 shows an engagement sequence that is given as an example for all the exemplary embodiments and configurations according to FIGS. 1 to 9.

[0032] FIGS. 1 to 9 show various embodiments of the multi-stage transmission in planetary design according to the invention, for example, as an automatic eight speed transmission or, more specifically, an automatic transmission for a vehicle, in particular a motor vehicle, whereby FIG. 10 shows one example of an engagement sequence to implement the various gear stages.

[0033] Independently of the respective embodiments, the multi-stage transmission is shown as a gear set with a housing 9 only in schematic form. Also indicated in schematic form are the drive An, for example as an internal combustion engine, and the output Ab. The proposed multi-stage transmission includes six shafts 1, 2, 3, 4, 5, 6 and a fixed housing coupling 0. Furthermore, at least one electric motor EM as well as a first planetary gear set RS1, a second planetary gear set RS2 and a third planetary gear set RS3 are provided, whereby a drive An, provided for example as an internal combustion engine, can be connected to a first shaft 1 by means of a zeroth shift element K0, which is designed as a clutch, and an output Ab is connected to a second shaft 2.

[0034] In order to select the at least eight forward gears G1, G2, G3, G4, G5, G6, G7, G8 that are provided, a first shift element K1, which is designed as a clutch; a second shift element K2, which is designed as a clutch; a third shift element K3, which is designed as a clutch; a fourth shift element K4, which is designed as a clutch; and a fifth shift element B1, which is designed as a brake, are provided. The at least one reverse gear ratio R is implemented electrically by means of the backwards rotating electric motor EM with the aid of a forward gear. A gear stage to reverse the direction of rotation is therefore not needed.

[0035] In order to implement a preceding gear ratio of the electric motor EM, it is provided, independently of the various design variants, that the first element of the first planetary gear set RS1 is permanently connected to the housing 9 by means of the fixed housing coupling 0. Furthermore, the first shaft 1, which can be connected to the drive An or, more specifically, to the internal combustion engine, is permanently connected to the second element of the first planetary gear set RS1. Finally, the rotor 10 of the electric motor EM is connected to the third element of the first planetary gear set RS1. In order to achieve the dual function of the preceding gear ratio so that it can also be used for an additional transmission ratio, the third element of the first planetary gear set RS1 can be connected by means of at least one shift element K3, K4 to at least one element of at least one additional planetary gear set RS2, RS3.

[0036] In the case of the gear set of the invention, it is provided that the rotor 10 of the electric motor EM and the third element of the first planetary gear set RS1 are permanently connected, for example, to the third shaft 3, whereby the rotor 10 can also be connected by means of other elements for reasons relating to the arrangement of the electric motor. In this way the first planetary gear set RS1 forms a transmission internal preceding gear ratio for the electric motor EM, whereby the third shaft 3 transmits a constant preceding gear ratio to the first shaft 1.

[0037] Preferably the third shaft 3 can be connected by means of the third shift element K3, which is designed as a clutch, and by means of the fourth shaft 4 to the third element of the second planetary gear set RS2 and to the first element of the third planetary gear set RS3. Furthermore, the third shaft 3 can be connected by means of the fourth shift element K4, which is designed as a clutch, and by means of the sixth shaft 6 to the first element of the second planetary gear set RS2.

[0038] Furthermore, the first element of the third planetary gear set RS3 and the third element of the second planetary gear set RS2 are permanently connected to the fourth shaft 4; and the first element of the second planetary gear set RS2 is permanently connected to the sixth shaft 6. In addition, the third element of the third planetary gear set RS3 and the second element of the second planetary gear set RS2 are permanently connected to the fifth shaft 5; and the second element of the third planetary gear set RS3 and the output Ab are permanently connected to the second shaft 2, whereby “permanently connected” generally means that a shiftable connection is not provided.

[0039] With respect to the shift elements involved in the gear ratios, it is provided that the first shift element K1 is designed as a clutch and connects the first shaft 1 to the fifth shaft 5 in an engaged or, more specifically, switched state. The second shift element K2 is designed as a clutch and connects the first shaft 1 to the sixth shaft 6 in the engaged state. The third shift element K3 is designed as a clutch and connects the third shaft 3 to the fourth shaft 4 in the engaged state. The fourth shift element K4 is designed as a clutch and connects the third shaft 3 to the sixth shaft 6 in the engaged state. Finally the fifth shift element B1 is designed as a brake and connects the fourth shaft 4 to the housing 9 in the engaged state.

[0040] In summary, all of the embodiments exhibit a particularly compact design due to the integrated preceding gear ratio of the electric motor EM, which is also involved in other gear ratios. The proposed connections between the individual gear sets RS1, RS2, RS3 result in low mechanical load of the components, and lower transmission losses due to the good gearing efficiency. Furthermore, an optimized series of gear ratios is implemented in the gear ratios that are provided.

[0041] FIGS. 1 to 3 show various schematic views of the invented gear set, in which each one of the three planetary gear sets RS1, RS2, RS3 is designed as a minus planetary gear set. FIG. 4 shows an alternative of the first design variant from FIG. 1, in which the multi-stage transmission has a plus planetary gear set as a first planetary gear set RS1. FIG. 5 shows an alternative, in which the second planetary gear set RS2 is designed as a plus planetary gear set. Finally, FIG. 6 shows an embodiment, in which the third planetary gear set RS3 is designed as a plus planetary gear set.

[0042] FIG. 7 shows a nested arrangement of the second and third planetary gear sets RS2 and RS3 in a coaxial arrangement of the drive An and the output Ab according to the first design variant. In this case the elements of the second planetary gear set RS2 and the third planetary gear set RS3 are arranged in essence in a common gear plane, whereby the third planetary gear set RS3 is disposed radially outside the second planetary gear set RS2. This type of arrangement has the advantage that the first element of the third planetary gear set RS3 and the third element of the second planetary gear set RS2 are assigned to a common shaft.

[0043] In the embodiment shown in FIG. 7, the first planetary gear set RS1 forms the first gear plane, and the second planetary gear set RS2 and the third planetary gear set RS3 form a second gear plane, which lies axially behind the first gear plane.

[0044] FIG. 8 also shows, by way of an example, a nested arrangement of the second planetary gear set RS2 and the third planetary gear set RS3 with a laterally arranged output Ab according to the second design variant. In this case the nested planetary gear sets RS2 and RS3 form the first gear plane and, located axially behind said first gear plane, the second gear plane is formed by the first planetary gear set RS1, to which the electric motor is also assigned. As a result, the electric motor EM is also located, when viewed axially, behind the first gear plane.

[0045] FIG. 9 shows another nested arrangement of the second planetary gear set RS2 and the third planetary gear set RS3. In contrast to the embodiment shown in FIG. 8, the first planetary gear set RS1 forms the first gear plane and the second planetary gear set RS2 with the third planetary gear set RS3 forms the second gear plane, located axially behind said first gear plane.

[0046] In the case of a minus planetary gear set it holds that the first element is designed as a sun gear SR1, SR2, SR3; the second element is designed as a planetary gear carrier or, more specifically, a web PT1, PT2, PT3; and the third element is designed as a ring gear HR1, HR2, HR3. In the case of a plus planetary gear set it holds that the first element is designed as a sun gear SR1, SR2, SR3; the second element as a ring gear HR1, HR2, HR3; and the third element as a planetary gear carrier or, more specifically, a web PT1, PT2, PT3.

[0047] The distinction between the first design variants according to FIGS. 1 and 2 and the second design variant according to FIG. 3 lies in the fact that in the second design variant the sequence of the planetary gear sets RS1, RS2, RS3 is changed. In the second design variant, starting from the drive side, the first planetary gear set RS1 as the first gear plane, the third planetary gear set RS3 as the second gear plane, and the second planetary gear set RS2 as the third gear plane are arranged axially one behind the other. This arrangement makes it possible to implement a lateral output Ab, with which the multi-stage transmission of the invention allows a front transverse arrangement or a rear transverse arrangement in the vehicle.

[0048] If the planetary gear sets RS1, RS2, RS3 are each designed as minus planetary gear sets, then the shafts 1, 2, 3, 4, 5, 6 in the multi-stage transmission of the invention are connected to the gear sets RS1, RS2, RS3 as follows.

[0049] The drive An can be connected by means of the zeroth shift element K0 to the first shaft 1. The first shaft 1 is permanently connected to the planetary gear carrier PT1 of the first planetary gear set RS1. The sun gear SR1 of the first planetary gear set RS1 is connected to the housing 9. The rotor 10 of the electric motor EM is connected to the ring gear HR1 of the first planetary gear set RS1. The rotor 10 of the electric motor EM and the ring gear HR1 of the first planetary gear set RS1 are permanently connected to the third shaft 3, whereby the third shaft 3 can be connected by means of the third shift element K3, which is designed as a clutch, and by means of the fourth shaft 4 to the ring gear HR2 of the second planetary gear set RS2 and to the sun gear SR3 of the third planetary gear set RS3. Furthermore, the third shaft 3 can be connected by means of the fourth shift element K4, which is designed as a clutch, and by means of the sixth shaft 6 to the sun gear SR2 of the second planetary gear set RS2. Furthermore, the sun gear SR3 of the third planetary gear set RS3 and the ring gear HR2 of the second planetary gear set RS2 are permanently connected to the fourth shaft 4. The sun gear SR2 of the second planetary gear set RS2 is permanently connected to the sixth shaft 6, whereby the ring gear HR3 of the third planetary gear set RS3 and the planetary gear carrier PT2 of the second planetary gear set RS2 are permanently connected to the fifth shaft 5. The planetary gear carrier PT3 of the third planetary gear set RS3 and the output Ab are permanently connected to the second shaft 2.

[0050] In the nested arrangements according to FIGS. 7 to 9, the connection between the ring gear HR2 of the second planetary gear set RS2 and the sun gear SR3 of the third planetary gear set occurs between the second planetary gear set RS2 and the third planetary gear set RS3 when they are designed as minus planetary gear sets. The result is a common component HR2/SR3, in which, on the one hand, an internal toothing is provided for the ring gear H2, and an external toothing is provided for the sun gear SR3, whereby the common component HR2/SR3 is connected to the shaft 4.

[0051] If one or more of the planetary gear sets RS1, RS2, RS3 is/are designed as a plus planetary gear set, then the aforementioned connection also applies, whereby it is not the planetary gear carrier PT1, PT2, PT3 that is provided as the second element of the planetary gear set, which is designed as a plus planetary gear carrier, but rather the ring gear HR1, HR2 HR3; and it is not the ring gear HR1, HR2, HR3 that is provided as the third element, but rather the planetary gear carrier PT1, PT2, PT3.

[0052] The following gear ratios result from the engagement sequence shown in FIG. 10. In order to implement the first forward gear G1, the fifth shift element B1, which is designed as a brake, and the second shift element K2, which is designed as a clutch, are engaged, whereby, in order to select the second forward gear G2, the fifth shift element B1, which is designed as a brake, and the fourth shift element K4, which is designed as a clutch, are engaged. In order to select the third forward gear G3, the fifth shift element B1, which is designed as a brake, and the first shift element K1, which is designed as a clutch, are engaged, whereby, in order to select the fourth forward gear G4, the first shift element K1, which is designed as a clutch, and the fourth shift element K4, which is designed as a clutch, are engaged. In order to select the fifth forward gear G5, the first shift element K1, which is designed as a clutch, and the second shift element K2, which is designed as a clutch, are engaged, whereby in order to select the sixth forward gear G6, the first shift element K1, which is designed as a clutch, and the third shift element K3, which is designed as clutch, are engaged. In order to select the seventh forward gear G7, the second shift element K2, which is designed as a clutch, and the third shift element K3, which is designed as a clutch, are engaged, whereby, in order to select the eighth forward gear G8, the third shift element K3, which is designed as a clutch, and the fourth shift element K4, which is designed as a clutch, are engaged. The reverse gear R is implemented electrically by means of one of the forward gear ratios.

REFERENCE NUMERALS

[0053] 0 fixed housing coupling [0054] 1 shaft [0055] 2 shaft [0056] 3 shaft [0057] 4 shaft [0058] 5 shaft [0059] 6 shaft [0060] 9 housing [0061] 10 rotor [0062] EM electric motor [0063] HR1 ring gear of the first planetary gear set [0064] PT1 planetary gear carrier of the first planetary gear set [0065] SR1 sun gear of the first planetary gear set [0066] HR2 ring gear of the second planetary gear set [0067] PT2 planetary gear carrier of the second planetary gear set [0068] SR2 sun gear of the second planetary gear set [0069] HR3 ring gear of the third planetary gear set [0070] PT3 planetary gear carrier of the third planetary gear set [0071] SR3 sun gear of the third planetary gear set [0072] HR2/SR3 common component as ring gear and sun gear [0073] G1 first forward gear [0074] G2 second forward gear [0075] G3 third forward gear [0076] G4 fourth forward gear [0077] G5 fifth forward gear [0078] G6 sixth forward gear [0079] G7 seventh forward gear [0080] G8 eighth forward gear [0081] R electrically implemented reverse gear [0082] An drive [0083] Ab output [0084] K0 zeroth shift element as a clutch [0085] K1 first shift element as a clutch [0086] K2 second shift element as a clutch [0087] K3 third shift element as a clutch [0088] K4 fourth shift element as a clutch [0089] B1 fifth shift element as a brake