ELECTRIC VEHICLE TRANSMISSION

Abstract

An electric vehicle transmission has a first driveshaft configured to be coupled to a first electric machine, and a main drive output shaft configured to be coupled to at least one drive axle. At least one gear-shifting element is provided, which when respectively actuated enables the first driveshaft and the main drive output shaft to be coupled to one another by way of a gear. The transmission can be provided in an electric vehicle in which electric machines can be integrated to provide drive power and to operate an auxiliary drive output. In addition, a second driveshaft serves to be coupled to a second electric machine and which can be coupled to an auxiliary driveshaft. In this case a shifting element is present, which when actuated couples the second driveshaft with the main drive output shaft. A method of operating an electric utility vehicle drive system is also disclosed.

Claims

1. An electric vehicle transmission (15) for an electric utility vehicle, the electric vehicle transmission (15) comprising: a first driveshaft (16) configured to be coupled to a first electric machine (13); a main drive output shaft (21) configured to be coupled to at least one drive axle (3); at least one gear-shifting element (37, 38, 39), the respective actuation of which couples the first driveshaft (16) with the main drive output shaft (21) by way of a gear; a second driveshaft (42) configured to be coupled to a second electric machine (14) and further configured to be coupled to an auxiliary driveshaft (46); and a shifting element (53), which when actuated couples the second driveshaft (42) to the main drive output shaft (21).

2. The electric vehicle transmission (15) according to claim 1, wherein when actuated, the shifting element (53) connects the second driveshaft (42) in a rotationally fixed manner to a first spur gear (52) which meshes with a second spur gear (51), and wherein the second spur gear (51) is coupled to the main drive output shaft (21).

3. The electric vehicle transmission (15) according to claim 1, wherein the shifting element (53) is a first shifting element and further comprising a second shifting element (45), wherein the first shifting element (53) is combined with the second shifting element (45) to form a shifting device (54), by the actuation element (55) of which the shifting device can be changed from a neutral position to a first position to actuate the first shifting element (53) and to a second position to actuate the second shifting element (45), wherein when actuated, the second shifting element (45) couples the second driveshaft (42) to the auxiliary driveshaft (46).

4. The electric vehicle transmission (15) according to claim 1, further comprising a countershaft (20) and wherein the at least one gear-shifting element comprises: a first gear-shifting element (37), which when actuated connects the first driveshaft (16) rotationally fixed to the main drive output shaft (21); and at least one further gear-shifting element (38, 39) having a closed condition in which a power flow takes place from the first driveshaft (16) via the countershaft (20) to the main drive output shaft (21) by way of one or more spur gear stages (18, 25; 18, 23) and with the engagement of an associated gear.

5. The electric vehicle transmission (15) according to claim 4, wherein the at least one gear-shifting element further comprises a second gear-shifting element (38) and a third gear-shifting element (39), wherein the countershaft (20) is coupled permanently by way of a first spur gear stage (18) to the first driveshaft (16); wherein when the second gear-shifting element (39) is actuated, the countershaft (20) can be coupled to the main drive output shaft (21) via a second spur gear stage (25) and, by closing the third gear-shifting element (38), by means of a third spur gear stage (23).

6. The electric vehicle transmission (15) according to claim 5, wherein: a first gear between the first driveshaft (16) and the main drive output shaft (21) is obtained by closing the second gear-shifting element (39), a second gear between the first driveshaft (16) and the main drive output shaft (21) is obtained by actuating the third gear-shifting element (38), and a third gear between the first driveshaft (16) and the main drive output shaft (21) is obtained by closing the first gear-shifting element (37).

7. The electric vehicle transmission (15) according to claim 5, wherein the first gear-shifting element (37), the second gear-shifting element 38), and the third gear-shifting element (39) are combined to form a shifting device (40), whose actuation element (41) operable between a neutral position and a plurality of shift positions, wherein each of the plurality of shift positions is associated with an actuation of one of the at least one gear-shifting elements (37; 38; 39).

8. The electric vehicle transmission (15) according to claim 4, wherein the countershaft (20) is arranged coaxially with the second driveshaft (42).

9. The electric vehicle transmission (15) according to claim 1, wherein the shifting element (45, 53) and/or an individual gear-shifting element of the at least one gear-shifting element (37, 38, 39) is in the form of a claw-type shifting element.

10. The electric vehicle transmission (15) according to claim 1, further comprising a transverse differential, wherein the main drive output shaft (21) is coupled to the transverse differential (30).

11. The electric vehicle transmission (15) according to claim 1, further comprising a separator clutch (36), a drive output shaft (9), and at least one further drive axle, wherein the main drive output shaft (21) is configured be coupled to the drive output shaft (9) by way of the separator clutch (36), wherein the separator clutch forms a coupling with the at least one further drive axle (4).

12. A drive system (2) for an electric utility vehicle, the drive system comprising the electric vehicle transmission (15) according to claim 1, the first electric machine (14), and the second electric machine (14), wherein a rotor of the first electric machine (13) is coupled to the first driveshaft (16) of the electric vehicle transmission (15) and a rotor of the second electric machine (14) is coupled to the second driveshaft (42).

13. An electric utility vehicle comprising a drive system (2) according to claim 12.

14. A method for operating a drive system (2) according to claim 12, the method comprising: actuating the at least one gear-shifting element (37, 38, 39) of the electric vehicle transmission (15) thereby coupling the first electric machine (13) to the main drive output shaft (21) with an associated gear engaged; and actuating the shifting element (53), during the coupling of the first electric machine (13) to the main drive output shaft (21) with the associated gear engaged, thereby coupling the second electric machine (14) to the main drive output shaft (21).

15. The method according to claim 14, comprising controlling the second electric machine (14) during the course of coupling the first electric machine (13) to the main drive output shaft (21) in the associated gear, and from L time of actuating the shifting element (53), in such manner that the second electric machine (14) contributes a rotation-speed-synchronous drive torque to the main drive output shaft (21).

16. (canceled)

17. A method of operating an electric utility vehicle drive system, comprising: providing a first electric machine; providing a second electric machine; providing an electric utility vehicle having a transmission comprising: a first driveshaft (16) configured to be coupled to the first electric machine (13); a main drive output shaft (21) configured to be coupled to at least one drive axle (3); a countershaft (20); one or more spur gear stages (18, 25; 18, 23); one or more gears; gear-shifting elements (37, 38, 39), which when actuated connects the first driveshaft (16) rotationally fixed to the main drive output shaft (21), wherein some of the gear-shifting elements (38, 39) have a closed condition in which a power flow takes place from the first driveshaft (16) via the countershaft (20) to the main drive output shaft (21) by way of the one or more spur gear stages (18, 25; 18, 23) and with the engagement of an associated gear of the one or more gears; a second driveshaft (42) configured to be coupled to the second electric machine (14) and further configured to be coupled to an auxiliary driveshaft (46); and a shifting element (53), which when actuated couples the second driveshaft (42) to the main drive output shaft (21); wherein respective actuation of the first gear-shifting element and the at least one further gear-shifting element couples the first driveshaft (16) with the main drive output shaft (21); closing the shifting element (53), resulting in one of the one or more gears between the first electric machine (13) and the main drive output shaft (21); providing support for a traction force by way of the second electric machine; changing between the one or more gears; and switching between the gear-shifting elements (37, 38, 39); wherein closing the shifting element and providing the support is performed during the course of changing between the one or more gears and switching between the gear-shifting elements (37, 38, 39).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0037] An advantageous embodiment of the invention, which is explained below, is illustrated in the drawings, which show.

[0038] FIG. 1: A schematic view of a drive-train of an electric utility vehicle;

[0039] FIG. 2: A schematic representation of a drive system of the drive-train shown in FIG. 1, in accordance with a preferred embodiment of the invention; and

[0040] FIGS. 3 to 7: Schematic views of various shift conditions of an electric vehicle transmission of the drive system shown in FIG. 2.

DETAILED DESCRIPTION

[0041] FIG. 1 shows a schematic view of a drive-train 1 of an electric utility vehicle, which vehicle is an electric working vehicle. Particularly preferably, this electric utility vehicle is an electrically driven tractor. The drive-train 1 comprises a drive system 2 and two drive axles 3 and 4, each having two drive wheels 5 and 6 or 7 and 8, respectively. Preferably the drive axle 4 is a front axle of the electric utility vehicle, whereas the drive axle 3 is a rear axle of the electric utility vehicle.

[0042] Here the two drive axles 3 and 4 are each coupled to the drive system 2, in such manner that for the drive axle 4 the connection is made by way of a drive output shaft 9 and a transmission 10, whereas the drive axle 3 is connected within the drive system 2.

[0043] Furthermore, the drive system 2 is provided with an auxiliary drive 11 in the form of a power take-off shaft 12, by way of which drive power can be supplied to a working device arranged on the electric utility vehicle.

[0044] FIG. 2 shows a schematic representation in the area of the drive system 2, which is designed in accordance with a preferred embodiment of the invention. In this case the drive system 2 comprises a first electric machine 13, a second electric machine 14 and an electric vehicle transmission 15 which in this case is in the form of a preferred possible design of the invention. The two electric machines 13 and 14 are each indicated only schematically and each consists—in a manner whose principle is known to those with a knowledge of the subject—of a rotor and a stator. The individual electric machines 13 and 14 can each be operated on the one hand as an electric motor and on the other hand as a generator.

[0045] In the present case—not illustrated here in greater detail—the rotor of the electric machine 13 is connected rotationally fixed to a first driveshaft 16 of the electric vehicle transmission 15, so that the rotor of the electric machine 13 and the first driveshaft 16 always rotate at the same speed. On the first driveshaft 16 a spur gear 17 of a spur gear stage 18 is arranged in a rotationally fixed manner, such that the spur gear 17 meshes within the spur gear stage 18 with a spur gear 19 which is arranged rotationally fixed on a countershaft 20. Accordingly, the first driveshaft 16 and the countershaft 20 are permanently coupled with one another by way of the spur gear stage 18. The countershaft 20 is here axially offset relative to the first driveshaft 16 and relative to a main drive output shaft 21 which latter is positioned coaxially with the first driveshaft 16.

[0046] Besides the spur gear 19 there are also arranged on the countershaft 20, in each case in a rotationally fixed manner, a spur gear 22 of a spur gear stage 23 and a spur gear 24 of a spur gear stage 25. The spur gear 22 meshes permanently with a spur gear 26 which, together with the spur gear 22 forms the spur gear stage 25 and is mounted rotatably on the main drive output shaft 21. In contrast, the spur gear stage 25 is formed by the permanent meshing of the spur gear 24 with a spur gear 27 which is also mounted rotatably on the main drive output shaft 21.

[0047] The main drive output shaft 21 carries at an axial end facing away from the first driveshaft 16 a bevel gear 28, which meshes with a drive input adjusting wheel 29 of a transverse differential 30. In this case the differential 30 is in the form of a bevel gear differential which can be locked and by means of which a distribution of a drive movement transmitted by the main drive output shaft 21 is passed on to driveshafts 31 and 32 of the drive axle 3. This distribution can take place with compensation of rotation speed differences between the driveshafts 31 and 32.

[0048] In addition, a spur gear 33 is arranged rotationally fixed on the main drive output shaft 21, which meshes permanently with a spur gear 35 in a spur gear stage 34. In this case the spur gear 35 can be fixed by means of a separator cutch 36 to the drive output shaft 9, which extends axially offset relative to the main drive output shaft 21. By actuating the separator clutch 36 the main drive output shaft 21 and the drive input shaft 9 are coupled to one another by means of the spur gear stage 34, whereby in addition a power flow is transmitted to the drive axle 4 and thereby realizes an all-wheel driving mode of the electric utility vehicle.

[0049] In the electric vehicle transmission 15 three gear-shifting elements 37, 38, and 39 are also provided, each in the form of an interlocking shifting element, which are therefore specifically unsynchronized claw-type shifting elements. When actuated, the gear-shifting element 37 connects the first driveshaft 16 rotationally fixed to the coaxially extending main drive output shaft 21, so that a fixed through-drive from the first driveshaft 16 and thus also the electric machine 13 to the main drive output shaft 21 takes place. In contrast, when actuated the gear-shifting element 38 connects the spur gear 27 to the main drive output shaft 21, whereby the main drive output shaft 21 is coupled to the first driveshaft 16 by way of the spur gear stages 18 and 25. Alternatively the first driveshaft 16 can also be coupled to the main drive output shaft 21 by way of the spur gear stages 18 and 23, for which purpose the gear-shifting element 39, which then fixes the spur gear 26 to the main drive output shaft 21, has to be closed.

[0050] Between the first driveshaft 16 and the main drive output shaft 21 there can accordingly be engaged a first gear by closing the gear-shifting element 38, a second gear by closing the gear-shifting element 39, and a third gear by closing the gear-shifting element 37. In each of the gears the electric machine 13 is coupled to the main drive output shaft 21 and thus also to the drive axle 3, and by additionally actuating the separator clutch 36 a coupling to the further drive axle 4 can be created.

[0051] In the present case the gear-shifting elements 37, 38, and 39 are combined in a shifting device 40 which comprises an actuation element 41. In particular this actuation element is in the form of a shifting sleeve and, besides a neutral position in which none of the gear-shifting elements 37, 38, and 39 is actuated, it can also be moved to three different shift positions of which in a first shift position the gear-shifting element 37, in a second shift position the gear-shifting element 38, and in a third shift position the gear-shifting element 39 is actuated.

[0052] As can also be seen from FIG. 2, the rotor of the electric machine 14—here not illustrated further—is connected rotationally fixed to a second driveshaft 42 of the electric vehicle transmission 15. This second driveshaft 42 is arranged coaxially with the countershaft 20, such that the said countershaft 20 is a hollow shaft that covers the driveshaft 42 axially and surrounds it radially.

[0053] On the second driveshaft 42 a spur gear 43 of a pump drive 44 is arranged in a rotationally fixed manner, so that via the pump drive 44 at least one hydraulic pump of the electric utility vehicle is permanently coupled to the second driveshaft 42 and thus also to the electric machine 14. At an end axially opposite the connection to the electric machine 14, the second driveshaft 42 can also be connected rotationally fixed by a shifting element 45 to an auxiliary driveshaft 46 which is arranged coaxially with the second driveshaft 42. This auxiliary driveshaft 46 is permanently coupled by a spur gear stage 47 to the power take-off shaft 12, since a spur gear 48 arranged rotationally fixed on the auxiliary driveshaft 46 meshes with a spur gear 49 which is positioned rotationally fixed on the power take-off shaft 12.

[0054] As a special feature, alternatively to being connected rotationally fixed to the auxiliary driveshaft 46, the second driveshaft 42 can also be coupled with the main drive output shaft 21. For that purpose, a spur gear stage 50 is provided, which consists of two spur gears 51 and 52 which are permanently engaged with one another. The spur gear 51 is arranged rotationally fixed on the main drive output shaft 21 between the spur gear 33 and the bevel gear 28, whereas the spur gear 52 is mounted rotatably on the auxiliary driveshaft 46. In this case the spur gear 52 can be connected rotationally fixed to the second driveshaft 42, whereby the second driveshaft 42 and the main drive input shaft 21 are coupled with one another by means of the spur gear stage 50.

[0055] In the present case the two shifting elements 45 and 53 are each in the form of interlocking shifting elements, so both the shifting element 45 and the shifting element 53 are unsynchronized claw-type shifting elements. The two shifting elements 45 and 53 are combined in a shifting device 54, which by means of its actuation element 55 is moved from a neutral position, depending on the direction of movement, such that either the shifting element 45 or the shifting element 52 is in its respective actuated condition. In the present case the shifting element 55 is preferably in the form of a shifting sleeve.

[0056] FIGS. 3 to 7 show various shift conditions of the electric vehicle transmission 15. For example, FIG. 3 shows a shift condition in which, between the first driveshaft 16 and the main drive output shaft 21, the first gear has been engaged by closing the gear-shifting element 38 by means of the actuation element 41 of the shifting device 40. This creates a power flow from the electric machine 13, via the first driveshaft 16 and by way of the spur gear stage 18, to the countershaft 20 from where the power flow then passes farther on via the spur gear stage 25 to the main drive output shaft 21. At the same time the shifting element 53 in the shifting device 54 is actuated, whereby the second driveshaft 42 as well, and thus also the electric machine 14, is coupled by means of the spur gear stage 50 to the main drive output shaft 21. In that way a common drive of the electric utility vehicle can take place when the electric machines 13 and 14 are operated as electric motors, wherein the electric machine 14 can assist the electric machine 13 in providing that drive. Furthermore, when the electric machines 13 and 14 are operated as generators, common braking of the electric utility vehicle can take place.

[0057] In the shift condition shown in FIG. 4, in contrast, the second gear is engaged between the first driveshaft 16 and the main drive output shaft 21 by closing the gear-shifting element 39, whereby, otherwise than the shift condition in FIG. 3, a power flow from the countershaft 20 to the main drive output shaft 21 takes place by way of the spur gear stage 23. Accordingly, the first driveshaft 16 and thus also the electric machine 13 are coupled to the main drive output shaft 21 by way of the spur gear stages 18 and 23. Again, the second driveshaft 42 and thus also the electric machine 14 are connected by means of the spur gear stage 50 to the main drive output shaft 21 by closing the shifting element 53. Thus, the electric machine 14 can assist the electric machine 13 for providing drive power or also during braking of the electric utility vehicle.

[0058] FIG. 5 shows a further shift condition of the electric vehicle transmission 15, wherein in this case, otherwise than in the two conditions in FIGS. 3 and 4, the gear-shifting element 37 is now closed, so that from the first driveshaft 16 a fixed through-drive to the main drive output shaft 21 is produced by engaging the third gear. Again, the electric machine 13 can be assisted by the electric machine 14 in driving or braking the electric utility vehicle, since by closing the shifting element 53 the electric machine 14 is likewise coupled via the second driveshaft 42 to the main drive output shaft 21.

[0059] A change between the gears that can be engaged between first driveshaft 16 and the main drive output shaft 21 can be carried out in such manner that when shifting between the gear-shifting elements 37 to 39 during a shifting operation from a current gear to a target gear with the accompanying interruption of the traction force between the driveshaft 16 and the main drive output shaft 21, the traction force is supported by the electric machine 14. This is possible because by way of the second driveshaft 42, the electric machine 14 is coupled by the spur gear stage 50 to the main drive output shaft 21.

[0060] During a shared drive input to the electric utility vehicle by the electric machines 13 and 14, the electric machine 14 is controlled in such manner that additional, rotation-speed-synchronous drive torque is contributed by the electric machine 14 to the main drive output shaft 21.

[0061] In contrast, in the shift condition shown in FIG. 6 the electric utility vehicle is powered or braked exclusively by the electric machine 14, since in this case only the shifting element 53 is closed and thus also only the electric machine 14 is coupled by way of the second driveshaft 42 to the main drive output shaft 21. On the other hand, the first driveshaft 16 and thus also the electric machine 13 is decoupled from the main drive output shaft 21 by moving the actuation element 41 of the shifting device 40 to its neutral position. Just as well, however, exclusive driving or exclusive braking of the electric utility vehicle by the electric machine 13 in one of the gears, as shown in FIGS. 3 to 5, can take place since in the closed condition of one of the gear-shifting elements 37 to 39 the shifting element 53 is not actuated at the same time.

[0062] Finally, FIG. 7 shows a shift condition of the electric vehicle transmission 15 in which the power take-off shaft 12 is operated by means of the electric machine 14. For this, the shifting element 45 of the shifting device 54 is actuated so that starting from the electric machine 14, a power flow takes place via the second driveshaft 42 to the auxiliary driveshaft 46 and thereafter via the spur gear stage 47 to the power take-off shaft 12. By correspondingly controlling the electric machine 14, without intermediate shifts of a separate power take-off shaft transmission, the usually necessary operating stages of the power take-off shaft 12 in the form of a normal stage and an eco-stage at 5040 r/min and a normal stage and an eco-stage at 1000 r/min can be obtained. In parallel, the electric utility vehicle can be powered or braked by the electric machine 13 in a shiftable gear.

[0063] By virtue of the design of an electric vehicle transmission in accordance with the invention, a suitable integration of electric machines for driving an electric utility vehicle and for operating a power take-off of this electric utility vehicle can be achieved.

INDEXES

[0064] 1 Drive-train [0065] 2 Drive system [0066] 3 Drive axle [0067] 4 Drive axle [0068] 5 Drive wheel [0069] 6 Drive wheel [0070] 7 Drive wheel [0071] 8 Drive wheel [0072] 9 Drive output shaft [0073] 10 Transmission [0074] 11 Auxiliary drive [0075] 12 Power take-off shaft [0076] 13 Electric machine [0077] 14 Electric machine [0078] 15 Electric vehicle transmission [0079] 16 Driveshaft [0080] 17 Spur gear [0081] 18 Spur gear stage [0082] 19 Spur gear [0083] 20 Countershaft [0084] 21 Main drive output shaft [0085] 22 Spur gear [0086] 23 Spur gear stage [0087] 24 Spur gear [0088] 25 Spur gear stage [0089] 26 Spur gear [0090] 27 Spur gear [0091] 28 Bevel gear [0092] 29 Drive input adjusting wheel [0093] 30 Transverse differential [0094] 31 Driveshaft [0095] 32 Driveshaft [0096] 33 Spur gear [0097] 34 Spur gear stage [0098] 35 Spur gear [0099] 36 Separator clutch [0100] 37 Gear-shifting element [0101] 38 Gear-shifting element [0102] 39 Gear-shifting element [0103] 40 Shifting device [0104] 41 Actuation element [0105] 42 Driveshaft [0106] 43 Spur gear [0107] 44 Pump drive [0108] 45 Shifting element [0109] 46 Auxiliary driveshaft [0110] 47 Spur gear stage [0111] 48 Spur gear [0112] 49 Spur gear [0113] 50 Spur gear stage [0114] 51 Spur gear [0115] 52 Spur gear [0116] 53 Shifting element [0117] 54 Shifting device [0118] 55 Actuation element