Drive train for a vehicle

Abstract

A drive-train for a vehicle having at least one electric drive unit (EM) which is, or can be, coupled by way of a driveshaft (AW) to at least a first transmission stage (i1), a second transmission stage (i2) and a third transmission stage (i3). At least one shifting device having at least two interlocking shifting elements (S1, S2) is provided for engaging the first and second transmission stages (i1, i2), and a frictional shifting element (S3) is provided for traction a force support of the first and the second transmission stages. The frictional shifting element (S3) is also provided for engaging the third transmission stage (i3).

Claims

1. A drive-train for a vehicle comprising: at least one electric drive unit which is coupleable, via a driveshaft, to at least a first transmission stage, a second transmission stage and a third transmission stage, the first transmission stage is a spur gear stage with a first fixed wheel and a first loose wheel, the second transmission stage is a second spur gear stage with a second fixed wheel and a second loose wheel, at least one shifting device having at least two interlocking shifting elements, for engaging the first and the second transmission stages, respectively, and a frictional shifting element for traction force support of the first and the second transmission stages, and either the third transmission stage is a third spur gear stage with a third fixed wheel and a third loose wheel, all of the first, the second and the third fixed wheels are fixed to one of the driveshaft and an intermediate shaft, and all of the first, the second and the third loose wheels are connectable to the other one of the driveshaft and the intermediate shaft, and the frictional shifting element being provided for engaging the third transmission stage, or the third transmission stage is a direct gear, and the frictional shifting element engages the direct gear.

2. The drive-train according to claim 1, wherein the interlocking shifting elements are formed as claw clutches.

3. The drive-train according to claim 1, wherein the interlocking shifting elements are formed as a dual claw clutch which has a neutral position and two shift positions.

4. The drive-train according to claim 1, wherein transmission stage is the direct gear.

5. The drive-train according to claim 4, wherein the first and the second loose wheels are connectable to the driveshaft in each case by a respective one of the interlocking shifting elements, and in the first and the second transmission stages a connection is made between the driveshaft and a drive output differential via a countershaft, a drive output constant and the intermediate shaft.

6. The drive-train according to claim 4, wherein the direct gear is implemented by connecting the driveshaft to the intermediate shaft via the frictional shifting element.

7. The drive-train according to claim 1, wherein the third transmission stage is a highest gear which has a lower transmission ratio than a transmission ratio of the first and the second transmission stages.

8. A drive-train for a vehicle comprising: at least one electric drive unit which is coupleable, via a driveshaft, to at least a first transmission stage, a second transmission stage and a third transmission stage, at least one shifting device having at least two interlocking shifting elements, for engaging the first and the second transmission stages, and a frictional shifting element for traction force support of the first and the second transmission stages, the frictional shifting element being provided for engaging the third transmission stage, the first transmission stage is a spur gear stage with a first fixed wheel and a first loose wheel, the second transmission stage is a second spur gear stage with a second fixed wheel and a second loose wheel, and the third transmission stage is a third spur gear stage with a third fixed wheel and a third loose wheel, and the first, the second and the third fixed wheels are fixed in common to one of the driveshaft and an intermediate shaft, the first and the second loose wheels are connectable, via a respective one of the interlocking shifting elements, to the other one of the driveshaft and the intermediate shaft, and the third loose wheel is connectable, via the frictional shifting element, to the other one of the driveshaft and the intermediate shaft.

9. The drive-train according to claim 8, wherein the first, the second and the third fixed wheels are fixed to the intermediate shaft, and the first and the second loose wheels are connectable, via the respective one of the interlocking shifting elements, to the driveshaft, and the third loose wheel is connectable to the driveshaft by the frictional shifting element, and the intermediate shaft is connected to a drive output differential.

10. The drive-train according to claim 8, wherein the first, the second and the third fixed wheels are connected to the driveshaft, and the first and the second loose wheels are connectable, via the respective one of the interlocking shifting elements, to the intermediate shaft, and the third loose wheel is connectable, via the frictional shifting element, to the intermediate shaft, and the intermediate shaft is connected to a drive output differential.

11. A drive-train for a vehicle comprising: at least one electric drive unit which is coupleable, via a driveshaft, to at least a first transmission stage, a second transmission stage and a third transmission stage, the first transmission stage has a first fixed wheel and a first loose wheel, and the second transmission stage has a second fixed wheel and a second loose wheel; a shifting device which is shiftable to at least first and second shift positions, the shifting device having at least first and second interlocking shifting elements, in the first shift position of the shifting device the first interlocking shifting element engaging the first transmission stage in a transmission of drive power from the driveshaft to a drive output, and in the second shift position of the shifting device the second interlocking shifting element engages the second transmission stage in the transmission of the drive power from the driveshaft to the drive output; and a frictional shifting element being shiftable to engage the third transmission stage in the transmission of the drive power from the driveshaft to the drive output to support a traction force of the first and the second transmission stages during shifting of the shifting device between the first and the second shift positions; and either the third transmission stage has a third fixed wheel and a third loose wheel, all of the first, the second and the third fixed wheels are fixed to one of the driveshaft and an intermediate shaft, and all of the first, the second and the third loose wheels are connectable to the other one of the driveshaft and the intermediate shaft, and the frictional shifting element engages the third transmission stage, or the third transmission stage is a direct gear, and the frictional shifting element engages the direct gear.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Below, the invention is explained further with reference to the drawings, which show:

(2) FIG. 1: A schematic view of a first embodiment of a drive-train according to the invention, with spur gear stages that can be engaged on the drive input shaft side as transmission stages mounted transversely;

(3) FIG. 2: A schematic view of a second embodiment of a drive-train according to the invention, with spur gear stages that can be engaged on the intermediate shaft side as transmission stages mounted transversely;

(4) FIG. 3: A schematic view of a third embodiment of a drive-train according to the invention, with spur gear stages that can be engaged on the drive input shaft side as transmission stages mounted longitudinally.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(5) FIGS. 1 to 3 show examples of different embodiments of a drive-train according to the invention for a vehicle, in particular a motor vehicle. The drive-train comprises an electric drive unit EM in the form of an electric machine, which drives a driveshaft AW directly or via a pre-transmission ratio 2. In addition at least three transmission stages i1, i2 and i3 are provided, which are connected at least by way of an intermediate shaft ZW to a drive output differential 3 or an axle transmission of the vehicle in order to drive the drive-wheels 4 of the vehicle. Associated with the transmission stages i1, i2 and i3 is a shifting device comprising two interlocking shifting elements S1 and S2 and one frictional shifting element S3. The transmission stages i1, i2 and i3 and the shifting elements S1, S2 and S3, together with an optional pre-transmission ratio, form a transmission device.

(6) FIG. 1 shows a first embodiment. The electric drive unit EM is connected by way of an optional pre-transmission ratio 2 to the driveshaft AW, and drives the latter. The transmission stages i1, i2 and i3 are in the form of spur gear stages, each respectively having a loose wheel 5, 6 and 7 and a fixed wheel 8, 9 and 10. To the driveshaft AW a first loose wheel 5 of the first transmission stage i1 is fitted and can be engaged. This can be coupled to the driveshaft AW by a first of the two interlocking shifting elements S1. To the driveshaft AW a second loose wheel 6 of the second transmission stage i2 is also fitted and can be engaged. This can be coupled to the driveshaft AW by a second of the two interlocking shifting elements S2. The first and second shifting elements S1 and S2 are in the form of a two-sided claw shifting element, which besides a central position in the middle can adopt at least two further shift positions in which, respectively, either the first shifting element S1 couples the first loose wheel 5 to the driveshaft AW or the second shifting element S2 couples the second loose wheel 6 to the driveshaft AW. Furthermore, a third loose wheel 7 of the third transmission stage i3 is fitted on the driveshaft AW and can be engaged therewith by means of the frictional shifting element S3 in the form of a frictional clutch. The associated fixed wheel 8 of the first transmission stage i1, the second fixed wheel 9 of the second transmission stage i2 and the third fixed wheel 10 of the third transmission stage i3 are mounted in a rotationally fixed manner on an intermediate shaft, this intermediate shaft ZW being arranged parallel to the driveshaft AW. On the intermediate shaft ZW is provided a further fixed wheel of a constant K in the form of a fourth transmission stage, which is provided in order to transmit the drive power from the intermediate shaft ZW to the drive output differential 3 and hence to the drive-wheels 4 of the vehicle. In this case the driveshaft AW forms a transmission input shaft and the intermediate shaft ZW a drive output shaft of the transmission device.

(7) The drive-train shown in FIG. 1 is designed for transverse mounting, wherein the first and second transmission stages i1 and i2 are engaged by claw clutches. The frictional clutch S3 is provided in addition for engaging the third transmission stage i3 for the powershift or supporting gearshift, via a higher gear during the engagement of the first or second transmission stage i1 or i2. For example, if a shift is to be made from the first transmission stage i1 to the second transmission stage i2, the shifting process begins with a load takeover by the frictional clutch S3. Then, the first shifting element S1 is disengaged. A rotational speed adaptation takes place until the second shifting element S2 can be closed. Now, the frictional clutch S3 can be opened again.

(8) Since the frictional clutch S3 can be used for engaging a transmission stage and for a powershift or a supporting gearshift, a further clutch is saved so that in accordance with the set objective the construction cost can be reduced. A powershift is possible both for a power upshift and for a power downshift, since the traction force interruption during upshifts can be compensated for by a boost (second power) at the electric drive unit EM. The use of interlocking shifting elements S1 and S2 in the form of claw-type shifting elements ensures lower fuel consumption and inexpensive actuation in the first two transmission stages i1 and i2.

(9) FIG. 2 shows a second embodiment variant. The electric drive unit EM is connected by way of an optional pre-transmission ratio 2 to the driveshaft AW and drives the latter. The transmission stages i1, i2 and i3 are each in the form of spur gear stages with respective loose wheels 5, 6 and 7 and respective fixed wheels 8, 9 and 10. Instead of being on the driveshaft AW the loose wheels 5, 6 and 7 of the transmission stages i1, i2 and i3 and the shifting elements S1, S2 and S3 are in this case arranged on the intermediate shaft ZW and the fixed wheels of the transmission stages i1, i2 and i3 are on the driveshaft AW. A first loose wheel 5 of the first transmission stage i1 is mounted on and can be engaged with the intermediate shaft ZW. It can be coupled to the intermediate shaft ZW by a first of the two interlocking shifting elements, S1. On the intermediate shaft ZW is also mounted a second loose wheel 6 of the second transmission stage i2. This can be coupled to the intermediate shaft ZW by means of a second of the two interlocking shifting elements S2. The first and second shifting elements S1 and S2 are made as a two-sided claw-type shifting element, which besides a central position in the middle can adopt at least two further shift positions in which, respectively, either the first shifting element S1 couples the first loose wheel 5 to the intermediate shaft ZW, or the second shifting element S2 couples the second loose wheel 6 to the intermediate shaft ZW. Furthermore, a third loose wheel 7 of the third transmission stage i3 is mounted on and can be engaged with the intermediate shaft ZW, which loose wheel can be coupled by means of the frictional shifting element S3 in the form of a friction clutch to the intermediate shaft ZW. The associated first fixed wheel 8 of the first transmission stage i1, the second fixed wheel 9 of the second transmission stage i2 and the third fixed wheel 10 of the third transmission stage i3 are mounted in a rotationally fixed manner on the driveshaft AW, and the intermediate shaft ZW is arranged parallel to the driveshaft AW. Again, on the intermediate shaft ZW is provided a fixed wheel of a constant K in the form of a fourth transmission stage, which is provided in order to transmit the drive power from the intermediate shaft ZW to the drive output differential 3 and from there to the vehicle wheels 4. In this case too, the driveshaft AW forms a transmission input shaft and the intermediate shaft ZW a drive output shaft of the transmission device.

(10) The drive-train shown in FIG. 2 is also provided for transverse mounting, wherein the first and second transmission stages i1 and i2 are engaged by means of claw shifting elements. The frictional clutch S3 is additionally provided for engaging the third transmission stage i3 for the powershift or supporting gearshift via a higher gear during the engagement of the first or second transmission stage i1 or i2. For example, if a shift is to be carried out from the first transmission stage i1 to the second transmission stage i2, the shifting process begins with a load takeover by the frictional clutch S3. Then the first shifting element S1 is disengaged. A rotational speed adaptation takes place until the second shifting element S2 can be closed. Now, the frictional clutch S3 can be opened again.

(11) Since the frictional clutch S3 can be used to engage a transmission stage and to carry out a powershift or supporting gearshift, a further clutch is saved so that in accordance with the set objective the construction cost can be reduced. A powershift is possible for both traction upshifts and traction downshifts, since the traction force interruption during traction upshifts can be compensated for by a boost (second power) at the electric drive unit EM. The use of interlocking shifting elements S1 and S2 in the form of claw-type shifting elements ensures lower fuel consumption and cheaper actuation in the first two transmission stages i1 and i2. In addition this embodiment is advantageous since the gearwheels can be made with larger diameters than in the first example embodiment.

(12) FIG. 3 shows an embodiment designed for longitudinal mounting of the drive-train. The electric drive unit EM is connected via an optional pre-transmission ratio 2 to the driveshaft AW, which it drives. The first two transmission stages i1 and i2 are in the form of spur gear stages with respective loose wheels 5 and 6 and respective fixed wheels 8 and 9. On the driveshaft AW is mounted a first loose wheel 5 of the first transmission stage i1, which can be engaged. This can be coupled to the driveshaft AW by a first, namely S1, of the two interlocking shifting elements. A second loose wheel 6, of the second transmission stage i2, is also mounted on and can be engaged with the driveshaft AW. This can be coupled to the driveshaft AW by a second, namely S2, of the two interlocking shifting elements. The first and second shifting elements S1 and S2 are made as a two-sided claw-type shifting element, which besides a central position in the middle can adopt at least two further shift positions, in which, respectively, either the first shifting element S1 couples the first loose wheel 5 to the driveshaft AW or the second shifting element S2 couples the second loose wheel 6 to the driveshaft AW. The associated first fixed wheel 8 of the first transmission stage i1 and the second fixed wheel 9 of the second transmission stage i2 are mounted rotationally fixed on a countershaft VG, this countershaft VG being arranged parallel to the driveshaft AW. On the countershaft VG there is a further fixed wheel 10 which belongs to a drive output constant AK, which is provided in order to transmit the drive power from the countershaft VG via an intermediate shaft ZW to the drive output differential 3 and hence to the wheels 4 of the vehicle. Here, the driveshaft AW forms a transmission input shaft and the intermediate shaft ZW a drive output shaft of the transmission device.

(13) In FIG. 3 the frictional clutch S3 is again additionally provided for engaging the third transmission stage i3 for the powershift or supporting gearshift via a higher gear during the engagement of the first or second transmission stage i1 or i2. The higher gear is the direct gear with a transmission ratio equal to 1. A shifting process with traction force support takes place as in the previous examples.

(14) Also with this embodiment, a further clutch for a third transmission stage is saved, in that the frictional clutch S3 can be used for engaging a transmission stage and for a powershift or supporting gearshift, whereby in accordance with the stated objective the construction cost can be reduced. A powershift is possible for traction upshifts and traction downshifts since the traction force interruption can be compensated for by a boost (second power) at the electric drive unit EM.

(15) All the embodiments shown are based on the same fundamental idea and differ only in their designs.

INDEXES

(16) EM Electric drive unit 2 Pre-transmission ratio AW Driveshaft i1 First transmission stage i2 Second transmission stage i3 Third transmission stage ZW Intermediate shaft 3 Drive output differential 4 Drive-wheels S1 Interlocking shifting element S2 Interlocking shifting element S3 Frictional shifting element 5 First loose wheel 6 Second loose wheel 7 Third loose wheel 8 First fixed wheel 9 Second fixed wheel 10 Third fixed wheel AK Drive output constant VG Countershaft