MOTOR VEHICLE TRANSMISSIONS, IN PARTICULAR ELECTRIC VEHICLE TRANSMISSIONS

Abstract

The invention relates to a motor vehicle transmission (6) having a drive input shaft (9), a drive output shaft (10), a first planetary gearset (P1), a second planetary gearset (P2), and a third planetary gearset (P3), where the drive input shaft (9) is provided for coupling to an electric machine (5). Furthermore, at least functionally a first shifting element (A), a second shifting element (B), and a third shifting element (C) are provided. In addition, the invention relates to a drive unit (4), a drive axle (3) and an electric vehicle.

Claims

1. A motor vehicle transmission (6), comprising: a drive input shaft (9) configured for connection to a drive machine; a drive output shaft (10); a first planetary gearset (P1), a second planetary gearset (P2), and a third planetary gearset (P3), each comprising a first element (E11, E12, E13), a second element (E21, E22, E23), and a third element (E31, E32, E33) in a form, respectively, of a sun gear, a planetary web, and a ring gear; a first shifting element (A), a second shifting element (B), and a third shifting element (C) or functional equivalents thereof; wherein the first element (E11) of the first planetary gearset (P1) is connected rotationally fixed to the drive input shaft (9) and the second element (E23) of the third planetary gearset (P3) is connected rotationally fixed to the drive output shaft (10); and wherein: the third element (E33) of the third planetary gearset (P3) is immobilized, the third element (E32) of the second planetary gearset (P2) is connected rotationally fixed to the second element (E23) of the third planetary gearset (P3) and to the output shaft (10), the second element (E21) of the first planetary gearset (P1) is connected rotationally fixed to the first element (E12) of the second planetary gearset (P2), the second element (E22) of the second planetary gearset (P2) is connected rotationally fixed to the first element (E13) of the third planetary gearset (P3), the third element (E31) of the first planetary gearset (P1) can be immobilized by means of the first shifting element (A) and is connected rotationally fixed to the second element (E22) of the second planetary gearset (P2) and to the first element (E13) of the third planetary gearset (P3) by means of the second shifting element (B), and two of the elements (E11, E21, E31) of the first planetary gearset (P1) can be brought into connection with one another by means of the third shifting element (C).

2. The motor vehicle transmission (6) according to claim 1, wherein: a first gear (G1) between the drive input shaft (9) and the drive output shaft (10) is obtained by closing the first shifting element (A), a second gear (G2) between the drive input shaft (9) and the drive output shaft (10) is obtained by actuating the second shifting element (B), and a third gear (G3) between the drive input shaft (9) and the drive output shaft (10) is obtained by closing the third shifting element (C).

3. The motor vehicle transmission (6) according to claim 1, wherein each of the shifting elements (A, B, C) is configured as an interlocking shifting element.

4. The motor vehicle transmission (6) according to claim 1, wherein actuating the third shifting element (C) connects the third element (E31) of the first planetary gearset (P1) rotationally fixed to the second element (E21) of the first planetary gearset (P1) or to the first element (E11) of the first planetary gearset (P1).

5. The motor vehicle transmission (6) according to claim 4, wherein the first shifting element (A), the second shifting element (B) and the third shifting element (C) are formed by a shifting device (18), the shifting device having a coupling element (19) configured to be positioned in a first shift position, a second shift position, and a third shift position, wherein in the first shift position the coupling element (19) functionally reproduces an actuated condition of the first shifting element (A) and immobilizes the third element (E31) of the first planetary gearset (P1), wherein in the second shift position the coupling element (19) functionally reproduces an actuated condition of the second shifting element (B) and connects the third element (E31) of the first planetary gearset (P1) rotationally fixed to the second element (E22) of the second planetary gearset (P2) and to the first element (E13) of the third planetary gearset (P3), and wherein in the third shift position the coupling element (19) functionally reproduces an actuated condition of the third shifting element (C) and connects the third element (E31) of the first planetary gearset (P1) rotationally fixed to the second element (E21) of the first planetary gearset (P1) or to the first element (E11) of the first planetary gearset (P1).

6. The motor vehicle transmission (6) according to claim 5, wherein the drive output shaft (10) is coupled to an input side of a differential gear system (13).

7. The motor vehicle transmission (6) according to claim 5, wherein the planetary gearsets (P1, P2, P3) are arranged after a connection point of the drive input shaft (9) that serves to couple the drive input shaft (9) to the drive machine, in a sequence of the first planetary gearset (P1), the second planetary gearset (P2), and the third planetary gearset (P3).

8. The motor vehicle transmission (6) according to claim 7, wherein the first shifting element (A), the second shifting element (B), and the third shifting element (C) are arranged axially between the first planetary gearset (P1) and the second planetary gearset (P2).

9. The motor vehicle transmission (6) according to claim 8, further comprising a positioning actuator (25), by means of which the coupling element (19) of the shifting device (18) that functionally reproduces the first shifting element (A), the second shifting element (B), and the third shifting element (C) can be moved to the first shift position, the second shift position, and the third shift position, the positioning actuator is located axially between the first planetary gearset (P1) and the second planetary gearset (P2).

10. An electric axle-drive unit for an electric vehicle (1), the drive unit (4) comprising: an electric machine (5) having a rotor; and a motor vehicle transmission (6) according to claim 1; wherein the rotor (8) of the electric machine (5) is coupled to the drive input shaft (9) of the motor vehicle transmission (6).

11. The electric axle-drive unit (4) according to claim 10, wherein the first planetary gearset (P1) of the motor vehicle transmission (6) is positioned axially at a level of and radially inside the electric machine (5).

12. A drive axle (3) for an electric vehicle (1), comprising a drive unit (4) according to claim 10.

13. The drive axle (3) according to claim 12, wherein the drive unit (4) is arranged in a plane with drive output shafts (14, 15), which are in each case associated with at least one drive wheel (16, 17) and are coupled to the drive output shaft (10) of the motor vehicle transmission (6).

14. An electric vehicle (1), comprising at least one drive axle (3) according to claim 12.

15. The motor vehicle transmission of claim 1, wherein each of the shifting elements (A, B, C) is configured as an unsynchronized claw-type shifting element.

16. The drive axle (3) for an electric vehicle (1), comprising a drive unit (4) according to claim 10, wherein the first planetary gearset (P1) of the motor vehicle transmission (6) is positioned axially at a level of and radially inside the electric machine (5).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Advantageous embodiments of the invention, which will be explained in greater detail below, are illustrated in the drawings, which show:

[0041] FIG. 1: A schematic representation of an electric vehicle corresponding to a. preferred embodiment of the invention;

[0042] FIG. 2: A schematic view of a drive axle of the electric vehicle shown with a drive unit corresponding to a preferred embodiment of the invention; and

[0043] FIG. 3: An example of a shifting scheme of a motor vehicle transmission of the drive unit shown in FIG. 2.

DETAILED DESCRIPTION

[0044] FIG. 1 shows a schematic representation of an electric vehicle 1, which in particular is an electric utility vehicle such as a transporter. Besides a steerable, non-driven axle 2, the electric vehicle 1 also has a drive axle 3 in which a drive unit 4 in the form of an electric axle-drive unit is provided. Whereas in this case the vehicle axle 2 is a front axle of the electric vehicle 1, the drive axle 3 is a rear axle of the electric vehicle 1. However, alternatively, or in addition to the drive axle 3, the vehicle axle 2 could also be designed as a driven axle.

[0045] FIG. 2 shows the drive axle 3 and in this case in particular the drive unit 4 in greater detail, the latter of which is made in accordance with a preferred embodiment of the invention. As can be seen, the drive unit 4 consists of an electric machine 5 and a motor vehicle transmission 6, which is configured in accordance with a preferred design option of the invention. In a manner whose principle is familiar to those with a knowledge of the subject, the electric machine 5 consists of a stator 7 and a rotor 8, such that the electric machine can be operated on the one hand as a generator and on the other hand as an electric motor.

[0046] Besides a drive input shaft 9 and a drive output shaft 10, the motor vehicle transmission 6 comprises three planetary gearsets P1, P2 and P3, each consisting respectively of a first element E11 or E12 or E13, a second element E21 or E22 or E23, and a third element E31 or E32 or E33. In this case the respective first element E11, E12 or E13 of the planetary gearset P1 or P2 or P3 is a sun gear in each case, whereas the respective second element E21, E22 or E23 of the planetary gearset P1 or P2 or P3 is a planetary web. In addition, the respective third element E31, E32 or E33 of the planetary gearset P1 or P2 or P3 is a ring gear of the planetary gearset P1 or P2 or P3 of the planetary gearset concerned.

[0047] On the respective planetary web of the planetary gearset concerned there is in each case at least one planetary gearwheel which is mounted to rotate, which meshes with the respective sun gear and also with the ring gear of the respective planetary gearset P1 or P2 or P3. Thus, the planetary gearsets P1, P2, and P3 are in this case all minus-planetary gearsets.

[0048] In the context of the invention, however, it can also be considered to make one or more of the planetary gearsets P1 to P3 as a plus-planetary gearset, and in that case, compared with their design as minus-planetary gearsets, the respective second element E21 or E22 or E23 will be a ring gear and the respective third element E31 or E32 or E33 will be the planetary web in each case. In addition, the stationary gear ratio of a respective planetary gearset made as a plus-planetary gearset must be increased by one compared with a design as a minus-planetary gearset. In a plus-planetary gearset, on the planetary web concerned at least one pair of planetary gearwheels are mounted to rotate, of which pair one planetary gearwheel meshes with the sun gear and one meshes with the ring gear, and the planetary gearwheels of the at least one pair of planetary gearwheels also mesh with one another.

[0049] In the present case the first element E11 of the first planetary gearset P1 is connected rotationally fixed to the drive input shaft 9, which is also connected rotationally fixed to the rotor 8 of the electric machine 5. Thus, the first element E11 of the first planetary gearset P1 and the rotor 8 are connected rotationally fixed to one another via the drive input shaft 9, so that the said first element E11 and the rotor 8 always rotate at the same rotation speed. In the context of the invention the first element E11 of the first planetary gearset P1 can be made integrally, as one piece with the drive input shaft 9. The second element E21 of the first planetary gearset P1 is permanently connected rotationally fixed to the first element E12 of the second planetary gearset P2, so that these two elements E21 and E12 also always rotate at the same rotation speed. Likewise, the second element E22 of the second planetary gearset P2 and the first element E13 of the third planetary gearset P3 are permanently connected rotationally fixed to one another, so that the second element E22 of the second planetary gearset P2 and the first element E13 of the third planetary gearset P3 always rotate together. The respective rotationally fixed connections in this case are preferably each formed by way of a respective intermediate shaft.

[0050] As can also be seen in FIG. 2, both the third element E33 of the third planetary gearset P3 is immobilized on a permanently fixed structural element 11 and is thus permanently prevented from rotating. In this case the said structural element 11 is preferably a transmission housing of the motor vehicle transmission 6, a part of such a transmission housing, or a component connected thereto in a rotationally fixed manner. In the context of the invention, in this case the third element E33 of the third planetary gearset P3 can be made integrally with the structural element 11. In contrast, the second element E23 of the third planetary gearset P3 and the third element E32 of the second planetary gearset P2 are connected rotationally fixed to one another and to the output shaft 10 of the motor vehicle transmission 6, so that the second element E23 of the third planetary gearset P3 and the third element E32 of the second planetary gearset P2 always rotate together with the output shaft 10. Accordingly, the second element E23 of the third planetary gearset P3 can if necessary be made integrally with the output shaft 10.

[0051] Besides the second element E23 of the third planetary gearset P3, the output shaft 10 is also permanently connected rotationally fixed to a differential cage 12 of a differential gear system. This differential gear system 13 is in the form of a conical gear differential, which in a manner whose principle is known to those familiar with the subject, distributes a drive power passing into the differential cage 12 by way of the output shaft 10, to drive output shafts 14 and 15 of the drive axle 3. In driving connection with the drive output shafts 14 and 15, there is a respective drive wheel 16 or 17 of the drive axle 3.

[0052] In the motor vehicle transmission 6 a shifting device 18 is also provided, by means of which various couplings with interlock can be effected. Here, the shifting device 18 is an unsynchronized shifting device which reproduces the function of three shifting elements A, B, and C, as indicated in FIG. 2. The shifting device 18 comprises a coupling element 19 which is designed in the form of a sliding sleeve and is guided on a guiding tooth array 20, rotationally fixed and axially displaceable on teeth 21. In this case the said teeth 21 are connected rotationally fixed to the third element E31 of the first planetary gearset P1. In addition, the coupling element 19 is provided with first engagement teeth 22, second engagement teeth 23, and third engagement teeth 24, and can be moved by an associated positioning actuator 25 to three different shift positions and two intermediate neutral positions. The positioning actuator 25 is preferably an electro-mechanical actuator.

[0053] In a first shift position the coupling element 19 of the shifting device 18 engages with the engagement teeth 22 in a tooth array 26 which is connected rotationally fixed to the structural element 11. Thereby, an actuated condition of the shifting element A is functionally obtained, in which the third element E31 of the first planetary gearset P1 is fixed by way of the coupling element 19 to the rotationally fixed structural element 11 and is thus prevented from rotating. This first shift position of the coupling element 19 is the one shown in FIG. 2.

[0054] From the first shift position the coupling element 19 of the shifting device 18 can be moved by the positioning actuator 25 to a first neutral position, in which the meshing engagement between the engagement teeth 22 and the teeth 26 is released and in which the third element E31 of the first planetary gearset P1 is decoupled. From the first neutral position further axial movement, besides changing from the first shift position, also moves the coupling element 19 to a second shift position in which the engagement teeth 23 mesh with teeth 27. These teeth 27 are connected rotationally fixed to the second element E22 of the second planetary gearset P2 and to the first element E13 of the third planetary gearset P3. The result of that engagement is that the third element E31 of the first planetary gearset P1 is connected rotationally fixed by way of the coupling element 19 to the second element E22 of the second planetary gearset P2 and to the first element E13 of the third planetary gearset P3. Thus, this second shift position of the coupling element 19 corresponds functionally to an actuated condition of the shifting element B.

[0055] From the second shift position the coupling element 19 can be moved by the positioning actuator 25 on the one hand in one axial direction back to the first neutral position, or alternatively in the other axial direction to a second neutral position in which the third element E31 of the first planetary gearset P1 is again completely decoupled.

[0056] The positioning actuator 25 can move the coupling element 19 from the second neutral position, on the one hand back to the second shift position and on the other hand, by an axial movement in the opposite direction, to a third shift position. In this third shift position, with its engagement teeth 24 the coupling element 19 engages with teeth 28, which are permanently connected rotationally fixed to the second element E21 of the first planetary gearset P1 and the first element E12 of the second planetary gearset P2. This reproduces the actuated condition of the shifting element C, in which the third element E31 of the first planetary gearset P1 is connected rotationally fixed to the second element E21 of the first planetary gearset P1 and to the first element E12 of the second planetary gearset P2. Owing to the rotationally fixed connection between the second element E21 and the third element E31 of the first planetary gearset P1. this results in blocking of the first planetary gearset P1 which then rotates as a block.

[0057] In the present case the drive unit 4 is arranged parallel to e drive axle 3 and in a plane with the drive output shafts 14 and 15, so that the drive unit 4 is arranged axially between the drive wheels 16 and 17. In this case the electric machine 5 is arranged axially adjacent to the drive wheel 17, and the first planetary gearset P1 of the motor vehicle transmission 6 is positioned axially at the level of, and radially inside the stator 7 of the electric machine 5. Axially after the first planetary gearset P1 there follow first the second planetary gearset P2 and then the third planetary gearset P3 and the differential 13, in such manner that the latter, together with the planetary gearsets P1 to P3, can be accommodated in a transmission housing of the motor vehicle transmission 6.

[0058] The shifting device 18 is positioned axially between the first planetary gearset P1 and the second planetary gearset P2, so that in this case the shifting device 18 is specifically arranged axially between the third planetary gearset P2 and a radial connection of the teeth 26 on the structural element 11. The positioning actuator 25 of the shifting device 18 is positioned axially also between the second planetary gearset P2 and the said radial connection and radially around the two planetary gearsets P1 and P2, in such manner that the positioning actuator 25 is coupled to the coupling element 19 by way of a shifting rod 29.

[0059] Furthermore, FIG. 3 shows an example shifting scheme for the motor vehicle transmission 6 in FIG. 2. It can be seen that in the motor vehicle transmission 6 a first gear G1, a second gear G2, and a third gear G3 can be engaged, and in the table of FIG. 3 an X is used in each case to indicate which of the shifting elements A, B, and C reproduced by the shifting device 18 has to be actuated. As described earlier, to produce an actuated condition of the shifting element A or B or C concerned, the coupling element 19 is moved to the respectively associated shift position.

[0060] The first gear G1 between the drive input shaft 9 and the drive output shaft 10 is obtained by actuating the shifting element A. Accordingly, in that case the third element E31 of the first planetary gearset P1 is fixed by the coupling element 19 to the structural element 11.

[0061] In contrast, to engage the second gear G2 the shifting element B has to be functionally actuated, so that the third element E31 of the first planetary gearset P1 is now connected rotationally fixed to the second element E22 of the second planetary gearset P2 and to the first element E13 of the third planetary gearset P3. Accordingly, to shift from the first gear G1 to the second gear G2 the coupling element 19 of the shifting device 18 has to be moved from the first shift position (actuated condition of the shifting element A), through the first neutral position and to the second shift position (actuated condition of the shifting element B).

[0062] Finally, the third gear G3 of the motor vehicle transmission 6 is engaged by functionally actuating the shifting element C. Correspondingly, in the shifting device 18 the coupling element 19 has to be moved to the shift position in which the engagement teeth 24 mesh with the teeth 28. Thereby, the third element E31 of the first planetary gearset P1 is connected rotationally fixed to the second element E21 of the first planetary gearset P1 so that the first planetary gearset P1 is blocked. To shift from the second gear G2 to the third gear G3, the coupling element 19 of the shifting device 18 has to be moved from the second shift position (actuated condition of the shilling element B) through the second neutral position to the third shift position (actuated condition of the shifting element C). During respective gearshifts between the gears G1 to G2 and G2 to G3, the requisite synchronized rotation speeds at the coupling element 19 are set by means of the electric machine 5 by corresponding rotation speed regulation.

[0063] By virtue of the design of a motor vehicle transmission according to the invention, different gears can be engaged by compact means.

INDEXES

[0064] 1 Electric vehicle [0065] 2 Vehicle axle [0066] 3 Drive axle [0067] 4 Drive unit [0068] 5 Electric machine [0069] 6 Motor vehicle transmission [0070] 7 Stator [0071] 8 Rotor [0072] 9 Drive input shaft [0073] 10 Drive output shaft [0074] 11 Structural element [0075] 12 Differential cage [0076] 13 Differential gear system [0077] 14 Drive output shaft [0078] 15 Drive output shaft [0079] 16 Drive wheel [0080] 17 Drive wheel [0081] 18 Shifting device [0082] 19 Coupling element [0083] 20 Guiding tooth array [0084] 21 Teeth [0085] 22 Engagement teeth [0086] 23 Engagement teeth [0087] 24 Engagement teeth [0088] 25 Positioning actuator [0089] 26 Teeth [0090] 27 Teeth [0091] 28 Teeth [0092] 29 Shifting rod [0093] P1 First planetary gearset [0094] P2 Second planetary gearset [0095] P3 Third planetary gearset [0096] E11 First element of the first planetary gearset [0097] E21 Second element of the first planetary gearset [0098] E31 Third element of the first planetary gearset [0099] E12 First element of the second planetary gearset [0100] E22 Second element of the second planetary gearset [0101] E32 Third element of the second planetary gearset [0102] E13 First element of the third planetary gearset [0103] E23 Second element of the third planetary gearset [0104] E33 Third element of the third planetary gearset [0105] A Shifting element [0106] B Shifting element [0107] C Shifting element [0108] G1 First gear [0109] G2 Second gear [0110] G3 Third gear