POWER-SPLIT DRIVELINE FOR A WORK MACHINE

Abstract

A power-split drive train having a main drive, three output shafts (Ab1, Ab2, Ab3) and a continuously variable powersplit transmission with three additional drive units. The transmission enables rotational speed variability at the shafts (Ab1, Ab2, Ab3). Furthermore, each drive unit (2a, 2b, 2c) has a respective energy converter (3a, 3b, 3c) which are all electrically connected. Drive unit (2a) has planetary gearset (4a) that is connected, via a first shaft (W1), to the main drive. Shaft (Ab1) is connected, via a second shaft (W2), to gearset (4a) and energy converter (3a) is connected, via a third shaft (W3), to gearset (4a). The drive unit (2a) is at least indirectly connected to drive unit (2b) which is connected by a fifth shaft (W5) to shaft (Ab2). Drive unit (2a) is at least indirectly connected to drive unit (2c) which is connected by a seventh shaft (W7) to shaft (Ab3).

Claims

1-10. (canceled)

11. A power-split drive train for a working machine, the power-split drive train comprising: a main drive element (1), first, second and third rotational-speed-variable drive output shafts (Ab1, Ab2, Ab3), and a continuously variable power-split transmission (8) having first, second and third additional drive units (2a, 2b, 2c), the transmission (8) being designed to enable rotational speed variability at the first, the second and the third drive output shafts (Ab1, Ab2, Ab3), each of the first, the second, and the third additional drive units (2a, 2b, 2c) comprising an energy converter (3a, 3b, 3c), and the energy converters (3a, 3b, 3c) being functionally connected to one another at least by an electric line (5), the first additional drive unit (2a), in addition to the energy converter (3a), also comprising a planetary gearset (4a), the main drive element (1) being connected by a first shaft (W1) to the planetary gearset (4a) of the first additional drive unit (2a), and the first drive output shaft (Ab1) being connected by a second shaft (W2) to the planetary gearset (4a) of the first additional drive unit (2a), the energy converter (3a) of the first additional drive unit (2a) being connected by a third shaft (W3) to the planetary gearset (4a) of the first additional drive unit (2a), the first additional drive unit (2a) being at least indirectly connected to the second additional drive unit (2b), and the second additional drive unit (2b) being connected by a fifth shaft (W5) to the second drive output shaft (Ab2), the first additional drive unit (2a) being at least indirectly connected to the third additional drive unit (2c) and the third additional drive unit (2c) being connected by a seventh shaft (W7) to the third drive output shaft (Ab3).

12. The power-split drive train according to claim 11 wherein the first additional drive unit (2a) is connected to the second additional drive unit (2b) by the second shaft (W2) and a fourth shaft (W4), the fifth shaft (W5) is connected to the energy converter (3b) of the second additional drive unit (2b) and is couplable to the fourth shaft (W4) by a shifting element (K2) of the second additional drive unit (2b), the first additional drive unit (2a) is connected by the first shaft (W1) and a sixth shaft (W6) to the third additional drive unit (2c), and the third additional drive unit (2c), in addition to the energy converter (3c), also comprises a planetary gearset (4c), the energy converter (3c) of the third additional drive unit (2c) is connected by an eighth shaft (W8) to the planetary gearset (4c) of the third additional drive unit (2c), the sixth shaft (W6) is connected to the planetary gearset (4c) of the third additional drive unit (2c), the third drive output shaft (Ab3) is connected by the seventh shaft (W7) to the planetary gearset (4c) of the third additional drive unit (2c), and the sixth shaft (W6) is couplable to the seventh shaft (W7) by a first shifting element (K3) of the third additional drive unit (2c).

13. The power-split drive train according to claim 11, wherein the first additional drive unit (2a) is connected by the second shaft (W2) and a fourth shaft (W4) to the second additional drive unit (2b), and the second additional drive unit (2b), in addition to the energy converter (3b), also comprises a planetary gearset (4b), the energy converter (3b) of the second additional drive unit (2b) is connected by a ninth shaft (W9) to the planetary gearset (4b) of the second additional drive unit (2b), and the fourth shaft (W4) is connected to the planetary gearset (4b) of the second additional drive unit (2b), and the fourth shaft (W4) is couplable to the fifth shaft (W5) by a shifting element (K2) of the second additional drive unit (2b), and the first additional drive unit (2a) is connected by the first shaft (W1) and a sixth shaft (W6) to the third additional drive unit (2c), and the third additional drive unit (2c), in addition to the energy converter (3c), also comprises a planetary gearset (4c), the energy converter (3c) of the third additional drive unit (2c) is connected by an eighth shaft (W8) to the planetary gearset (4c) of the third additional drive unit (2c), the sixth shaft (W6) is connected to the planetary gearset (4c) of the third additional drive unit (2c) and the third drive output shaft (Ab3) is connected by the seventh shaft (W7) to the planetary gearset (4c) of the third additional drive unit (2c), and the sixth shaft (W6) is couplable to the seventh shaft (W7) by a first shifting element (K3) of the third additional drive unit (2c).

14. The power-split drive train according to claim 11, wherein the first additional drive unit (2a) is connected by the second shaft (W2) and a fourth shaft (W4) to the second additional drive unit (2b), the fifth shaft (W5) is connected to the energy converter (3b) of the second additional drive unit (2b) and is couplable by a shifting element (K2) of the second additional drive unit (2b) to the fourth shaft (W4), and the first additional drive unit (2a) is connected by the first shaft (W1) and a sixth shaft (W6) to the third additional drive unit (2c), the seventh shaft (W7) is connected to the energy converter (3c) of the third additional drive unit (2c) and is couplable, by a first shifting element (K3) of the third additional drive unit (2c), to the sixth shaft (W6).

15. The power-split drive train according to claim 11, wherein the first additional drive unit (2a) is connected by way of the second shaft (W2) and a fourth shaft (W4) to the second additional drive unit (2b), and the second additional drive unit (2b), in addition to the energy converter (3b), also comprises a planetary gearset (4b), the energy converter (3b) of the second additional drive unit (2b) is connected by a ninth shaft (W9) to the planetary gearset (4b) of the second additional drive unit (2b), the fourth shaft (W4) is connected to the planetary gearset (4b) of the second additional drive unit (2b), the second drive output shaft (Ab2) is connected by the fifth shaft (W5) to the planetary gearset (4b) of the second additional drive unit (2b), and the fourth shaft (W4) is couplable by a shifting element (K2) of the second additional drive unit (2b) to the fifth shaft (W5), the first additional drive unit (2a) is connected by the first shaft (W1) and a sixth shaft (W6) to the third additional drive unit (2c) and the seventh shaft (W7) is connected to the energy converter (3c) of the third additional drive unit (2c) and is couplable to the sixth shaft (W6) by a first shifting element (K3) of the third additional drive unit (2c).

16. The power-split drive train according to claim 11, wherein the first shaft (W1) and the second shaft (W2) are couplable to one another by a shifting element (K1) of the first additional drive unit (2a).

17. The power-split drive train according to claim 11, wherein the seventh shaft (W7) is rotationally fixable relative to a housing (7) by a second shifting element (B1) of the third additional drive unit (2c).

18. The power-split drive train according to claim 11 wherein the electric line (5) is at least indirectly connected to an energy storage device (9).

19. The power-split drive train according to claim 11, wherein the energy converters (3a, 3b, 3c) of the first, the second, and the third additional drive units are designed to be electrically operated, and the electric line (5) comprises an interface (6) for at least one of delivery and uptake of electric power.

20. A working machine comprising: a power-split drive train for a working machine comprising: a main drive element (1), first, second and third rotational-speed-variable drive output shafts (Ab1, Ab2, Ab3), and a continuously variable power-split transmission (8) having first, second and third additional drive units (2a. 2b, 2c), the transmission (8) being designed to enable rotational speed variability at the first, the second and the third drive output shafts (Ab1, Ab2, Ab3), each of the first, the second, and the third additional drive units (2a, 2b, 2c) comprising an energy converter (3a, 3b, 3c), the energy converters (3a, 3b, 3c) being functionally connected to one another at least by an electric line (5), the first additional drive unit (2a), in addition to the energy converter (3a), also comprising a planetary gearset (4a), the main drive element (1) being connected by a first shaft (W1) to the planetary gearset (4a) of the first additional drive unit (2a), the first drive output shaft (Ab1) being connected by a second shaft (W2) to the planetary gearset (4a) of the first additional drive unit (2a), and the energy converter (3a) of the first additional drive unit (2a) being connected by a third shaft (W3) to the planetary gearset (4a) of the first additional drive unit (2a), the first additional drive unit (2a) being at least indirectly connected to the second additional drive unit (2b), and the second additional drive unit (2b) is connected by a fifth shaft (W5) to the second drive output shaft (Ab2), and the first additional drive unit (2a) being at least indirectly connected to the third additional drive unit (2c), and the third additional drive unit (2c) being connected by a seventh shaft (W7) to the third drive output shaft (Ab3).

21. A power-split drive train for a working machine comprising: a main drive element; first, second and third rotational-speed-variable drive output shafts; a continuously variable powersplit transmission comprising first, second and third additional drive units, and the transmission (8) being designed to enable rotational speed variability at the three drive output shafts, each of the first, the second and the third additional drive units comprises an energy converter, and the energy converters of the first, the second and the third additional drive units being functionally connected to one another by an electric line (5); the first additional drive unit further comprises a planetary gearset, and the planetary gearset of the first additional drive unit being connected, via a first shaft, to the main drive element, and being connected, via a second shaft, to the first drive output shaft, and being connected, via a third shaft, the energy converter of the first additional drive unit; the first additional drive unit being at least indirectly connected to each of the second and the third additional drive units; the second additional drive unit being connected, via a further shaft (W5), to the second drive output shaft (Ab2); and the third additional drive unit (2c) being connected, via another shaft (W7), to the third drive output shaft (Ab3).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Below, four example embodiments of the invention are explained in more detail with reference to the six drawings, which show:

[0023] FIG. 1: A schematic representation of a first embodiment of a power-split drive train according to the invention,

[0024] FIG. 2: A schematic representation of a second embodiment of a power-split drive train according to the invention,

[0025] FIG. 3: A shifting matrix for the power-split drive trains according to FIGS. 1 and 2,

[0026] FIG. 4: A schematic representation of a third embodiment of a power-split drive train according to the invention,

[0027] FIG. 5: A schematic representation of a fourth embodiment of a power-.split drive train according to the invention, and

[0028] FIG. 6: A shifting matrix for the power-split drive trains according to FIGS. 4 and 5.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0029] As shown in FIGS. 1, 2, 4 and 5, a power-split drive train according to the invention for a working machine—not shown here—comprises a main drive element 1 and a continuously variable power-split transmission 8 with first, second and third additional drive units 2a, 2b, 2c, wherein the continuously variable power-split transmission 8 is designed to enable rotational speed variability at first, second and third drive output shafts Ab1, Ab2 and Ab3. Each of the three additional drive units 2a, 2b, 2c has an energy converter 3a, 3b, 3c and the energy converters 3a, 3b, 3c are functionally connected with one another by way of an electric line 5 and can be controlled by a respective control device—not shown here. In this case the main drive element 1 is an internal combustion engine, preferably a diesel engine. The first drive output shaft Ab1 is a rear axle, the second drive output shaft Ab2 is a front axle and the third drive output shaft Ab3 is an auxiliary power take-off shaft. By means of the third drive output shaft Ab3, in particular torque and rotational movement can be provided, preferably for powering working equipment or attachments.

[0030] The first additional drive unit 2a comprises the energy converter and a planetary gearset 4a with a first, second and third shaft W1, W2, W3, and is designed as a CVU. In the present case all the energy converters 3a, 3b, 3c are electric machines and the electric line 5 is designed to carry electrical energy. Moreover, in the line 5 there is formed an interface 6 which enables electrical energy to be fed into the line 5 and thus supplied to the energy converters 3a, 3b, 3c. In particular the interface 6 is connected to a mains terminal not shown here so that the energy converters 3a, 3b, 3c can be supplied from the mains terminal with electrical energy, while excess energy can be fed back into the mains terminal.

[0031] The main drive element 1 is connected by the first shaft W1 to the planetary gearset 4a of the first additional drive unit 2a. Furthermore, the first drive output shaft Ab1 is connected by the second shaft W2 to the planetary gearset 4a of the first additional drive unit 2a. The energy converter 3a of the first additional drive unit 2a is connected by the third shaft W3 to the planetary gearset 4a of the first additional drive unit 2a. In addition the first shaft W1 can be coupled to the second shaft W2 by means of a shifting element K1 of the first additional drive unit 2a. The shifting element K1 of the first additional drive unit 2a couples any two shafts W1, W2, W3 of the planetary gearset 4a of the first additional drive unit 2a to one another, in particular a sun gear and a carrier, a carrier and a ring gear, or a sun gear and a ring gear. An essential feature is the block circulation produced by the coupling of any two of the shafts W1, W2, W3 of the planetary gearset 4a of the first additional drive unit 2a. The block circulation is produced by coupling a driven shaft of the planetary gearset 4a of the first additional drive unit 2a, for example the sun gear, to a second shaft of the planetary gearset 4a of the first additional drive unit 2a, for example the ring gear. This compels the third shaft of the planetary gearset 4a of the first additional drive unit 2a, for example the carrier, to rotate at the same speed.

[0032] As shown in FIG. 1 the second shaft W2 and the first drive output shaft Ab1 are connected to the fourth shaft W4. By way of the second shaft W2 and the fourth shaft W4 the first additional drive unit 2a is connected to the second additional drive unit 2b. The second additional drive unit 2b comprises an energy converter 3b which is connected by a fifth shaft W5 to the second drive output shaft Ab2 and which can be coupled to the fourth shaft W4 by means of a shifting element K2 of the second additional drive unit 2b. In addition the first additional drive unit 2a is connected to the third additional drive unit 2c by the first shaft W1 and a sixth shaft W6. The third additional drive unit 2c has an energy converter 3c of the third additional drive unit 2c and a planetary gearset 4c of the third additional drive unit 2c, and is designed as a CVU. The energy converter 3c of the third additional drive unit 2c is connected by an eighth shaft W8 to the planetary gearset 4c of the third additional drive unit 2c. Furthermore, the third drive output shaft Ab3 is connected to the planetary gearset 4c of the third additional drive unit 2c by a seventh shaft W7. In addition the sixth shaft W6 can be coupled to the seventh shaft W7 by means of a first shifting element K3 of the third additional drive unit 2c, whereas the seventh shaft W7 can be held fixed relative to a housing 7 by means of a second shifting element B1 of the third additional drive unit 2c in the form of a brake,

[0033] FIG. 2 shows a schematic representation of a second embodiment of the power-split drive train. This differs from the embodiment shown in FIG. 1, in that the second additional drive unit 2b is designed as a CVU. Thus, like the first and third additional drive units 2a and 2c the second additional drive unit 2b too comprises an energy converter 3b and a planetary gearset 4b. The energy converter 3b of the second additional drive unit 2b is connected to the planetary gearset 4b of the second additional drive unit 2b by a ninth shaft W9. Moreover, the second drive output shaft Ab2 is connected to the planetary gearset 4b of the second additional drive unit 2b by the fifth shaft W5. In addition the fourth shaft W4 is connected to the planetary gearset 4b of the second additional drive unit 2b, and can be coupled to the fifth shaft W5 by means of the shifting element K2 of the second additional drive unit 2b. Furthermore, by way of the electric interface 6 an energy storage device 9 is connected to the electric line 5 and thus to the respective energy converters 3a, 3b, 3c. In other respects the embodiment shown in FIG. 2 corresponds to the embodiment described in FIG. 1.

[0034] FIG. 3 shows a shifting matrix for the two power-split drive trains according to the invention according to FIGS. 1 and 2. Vertically downward are shown eleven different shifting conditions S1 to S11. Horizontally to the right are shown the respective shifting elements K1, K2, K3 and B1. Cells left empty in the shifting matrix indicate that the corresponding shifting element K1, K2, K3 or B1 is open, i.e., that in those cases the shifting element K1, K2, K3, B1 does not transmit any force or torque. A cell containing a cross in the shifting matrix indicates that the corresponding shifting element K1, K2, K3, B1 is actuated or closed.

[0035] To form any CVT structure (CVT=Continuously Variable Transmission) at least two energy converters 3a, 3b, 3c have to interact synergistically. Thus, at least two energy converters 3a, 3b, 3c form a variator by which the CVT structure is formed. In this, at least one of the energy converters 3a, 3b, 3c is designed to act as a motor and the at least one other energy converter is designed to act as a generator.

[0036] Below, three different CVT structures are explained for the first drive output shaft Ab1. An ‘input-coupled’ CVT structure for the first drive output shaft Ab1 is understood to mean that on its input side the first additional drive unit 2a has a fixed rotational speed ratio. Thus, the energy converter 3a of the first additional drive unit 2a is connected in a rotationally fixed manner to the main drive element 1. An ‘output-coupled’ CVT structure for the first drive output shaft Ab1 is understood to mean that the first additional drive unit 2a has a fixed rotational speed ratio on its output side. Thus, the energy converter 3a of the first additional drive unit 2a is connected in rotationally fixed manner to the first drive output shaft Ab1. An ‘input-output-coupled’ CVT structure for the first drive output shaft Ab1 is understood to mean that the first additional drive unit 2a has a fixed rotational speed ratio on both the input and the output sides. Thus, the energy converter 3a of the first additional drive unit 2a is connected in a rotationally fixed manner both to the main drive element 1 and to the first drive output shaft Ab1. By means of the three energy converters 3a, 3b, 3c, operation is possible exclusively with the input-coupled CVT structure, or exclusively with the output-coupled CVT structure, or in a mixed operating mode between the input-coupled CVT structure and the output-coupled CVT structure.

[0037] To obtain the first shifting condition S1 in the power-split drive train, the shifting element K3 is closed and the three shifting elements K1, K2 and B1 are open. For the first drive output shaft Ab1 this produces the input-coupled CVT structure. Thus, rotational speed variability is obtained for the first and second drive output shafts Ab1, Ab2.

[0038] To obtain the second shifting condition S2 in the power-split drive train, the two shifting elements K2 and K3 are closed and the two shifting elements K1 and B1 are open. For the first drive output shaft Ab1 this produces the input-coupled CVT structure, the output-coupled CVT structure and the input-output-coupled CVT structure. Rotational speed variability is thus obtained for the first drive output shaft Ab1.

[0039] To obtain the third shifting condition S3 in the power-split drive train, the shifting element B1 is closed and the three shifting elements K1, K2 and K3 are open. For the first drive output shaft Ab1 this produces an input-coupled CVT structure. Thus, rotational speed variability is obtained for the first and second drive output shafts Ab1, Ab2. Moreover, the third drive output shaft Ab3 is held fixed,

[0040] To obtain the fourth shifting condition S4 in the power-split drive train, the two shifting elements K2 and B1 are closed and the two shifting elements K1 and K3 are open. For the first drive output shaft Ab1 this produces the input-coupled CVT structure, the output-coupled CVT structure and the input-output-coupled CVT structure. Thus, rotational speed variability is obtained for the first drive output shaft Ab1. Moreover, the third drive output shaft Ab3 is held fixed.

[0041] To obtain the fifth shifting condition S5 in the power-split drive train, the shifting element K2 is closed and the three shifting elements K1, K3 and B1 are open. For the first drive output Ab1 this produces an output-coupled CVT structure. Thus, rotational speed variability is obtained for the first and third drive output shafts Ab1, Ab3.

[0042] To obtain the sixth shifting condition S6 in the power-split drive train, the two shifting elements K1 and K3 are closed and the two shifting elements K2 and B1 are open. Rotational speed variability is obtained only for the second drive output shaft Ab2.

[0043] To obtain the seventh shifting condition S7 in the power-split drive train, the shifting element B1 is open and the three shifting elements K1, K2, K3 are closed. In this seventh shifting condition S7 none of the three drive output shafts Ab1, Ab2, Ab3 has rotational speed variability.

[0044] To obtain the eighth shifting condition S8 in the power-split drive train, the two shifting element K1 and B1 are closed and the two shifting elements K2 and K3 are open. For the second drive output shaft Ab2 this produces rotational speed variability. Moreover, the third drive output shaft Ab3 is held fixed.

[0045] To obtain the ninth shifting condition S9 in the power-split drive train, the shifting element K3 is open and the three shifting elements K1, K2 and B1 are closed. In this ninth shifting condition S9 none of the three drive output shafts Ab1, Ab2, Ab3 has rotational speed variability. Moreover, the third drive output shaft Ab3 is held fixed.

[0046] To obtain the tenth shifting condition S10 in the power-split drive train, the two shifting elements K1 and K2 are closed and the two shifting elements K3 and B1 are open. This produces rotational speed variability for the third drive output shaft Ab3.

[0047] To obtain the eleventh shifting condition S11 in the power-split drive train, the shifting element K1 is closed and the three shifting elements K2, K3 and B1 are open. This produces rotational speed variability for the second and third drive output shafts Ab2 and Ab3.

[0048] FIG. 4 shows a schematic representation of a third embodiment of the power-split drive train 1. This differs from the embodiment shown in FIG. 1, in that the third additional drive unit 2c is not designed as a CVU and does not therefore have a planetary gearset 4c. Thus, like the second additional drive unit 2b the third additional drive unit 2c only comprises the energy converter 3c of the third additional drive unit 2c. The first additional drive unit 2a is connected to the third additional drive unit 2c by way of the sixth shaft W6. The energy converter 3c of the third additional drive unit 2c is connected by the seventh shaft W7 to the third drive output shaft Ab3 and can be coupled to the sixth shaft W6 by means of first shifting element K3 of the third additional drive unit 2c. In addition the energy converter 3c of the third additional drive unit 2c is connected by way of the electric line 5 to the respective energy converter 3a and 3b of the first and second additional drive unit 2a, 2b. In other respects the embodiment shown in FIG. 4 corresponds to the embodiment described in FIG. 1.

[0049] FIG. 5 shows a schematic representation of a fourth embodiment of the power-split drive train 1. This differs from the embodiment shown in FIG. 1, in that the second additional drive unit 2b is designed as a CVU and the third additional drive unit 2c has no planetary gearset 4c and is therefore not designed as a CVU. Thus, the second additional drive unit 2b comprises an energy converter 3b and a planetary gearset 4b. The energy converter 3b of the second additional drive unit 2b is connected by a ninth shaft W9 to the planetary gearset 4b of the second additional drive unit 2b. In addition the second drive output shaft Ab2 is connected by the fifth shaft W5 to the planetary gearset 4b of the second additional drive unit 2b. Furthermore, the fourth shaft W4 is connected to the planetary gearset 4b of the second additional drive unit 2b and can be coupled to the fifth shaft W5 by means of the shifting element K2 of the second additional drive unit 2b. On the other hand the third additional drive unit 2c has no planetary gearset 4c but only the energy converter 3c. The first additional drive unit 2a is connected to the third additional drive unit 2c by the sixth shaft W6. The energy converter 3c of the third additional drive unit 2c is connected by the seventh shaft W7 to the drive output shaft Ab3 and can be coupled by means of the first shifting element K3 of the third additional drive unit 2c to the sixth shaft W6. In addition the energy converter 3c of the third additional drive unit 2c is connected by way of the electric line 5 to the respective energy converter 3a and 3b of the first and second additional drive unit 2a, 2b. In other respects the embodiment shown in FIG. 5 corresponds to the embodiment described in FIG. 1.

[0050] FIG. 6 shows a shifting matrix for the two power-split drive trains according to the invention shown in FIGS. 4 and 5. Vertically downward seven different shifting conditions S1 to S7 are shown. Horizontally to the right are shown the respective shifting elements K1, K2 and K3. The empty cells in the shifting matrix indicate that the corresponding shifting element K1, K2 and K3 is open, i.e. that in those cases the corresponding shifting element K1, K2 and K3 does not transmit any force or torque. A cell containing a cross indicates that the corresponding shifting element K1, K2 or K3 is actuated or closed.

[0051] To obtain the first shifting condition S1 in the power-split drive train, the shifting element K3 is closed and the two shifting elements K1 and K2 are open. This produces an input-coupled CVT structure for the first drive output shaft Ab1. Thus, rotational speed variability is obtained for the first and second drive output shafts Ab1, Ab2.

[0052] To obtain the second shifting condition S2 in the power-split drive train, the two shifting elements K2 and K3 are closed and the shifting element K1 is open. For the first drive output shaft Ab1 this produces an input-coupled additional drive unit structure, an output-coupled CVT structure and an input-output-coupled CVT structure. Thus, rotational speed variability is obtained for the first drive output shaft Ab1.

[0053] To obtain the third shifting condition S3 in the power-split drive train, the shifting element K2 is closed and the two shifting elements K1 and K3 are open. For the first drive output shaft Ab1 this produces an output-coupled CVT structure. Thus, rotational speed variability is obtained for the first and third drive output shafts Ab1, Ab3.

[0054] To obtain the fourth shifting condition S4 in the power-split drive train, the two shifting elements K1 and K3 are closed and the shifting element K2 is open. This produces rotational speed variability for the second drive output shaft Ab2.

[0055] To obtain the fifth shifting condition S5 in the power-split drive train, all three of the shifting elements K1, K2 and K3 are dosed. In the fifth shifting condition none of the three drive output shafts Ab1, Ab2 and Ab3 has rotational speed variability.

[0056] To obtain the sixth shifting condition S6 in the power-split drive train, the two shifting elements K1 and K2 are dosed and the shifting element K3 is open. Rotational speed variability is only obtained for the third drive output shaft Ab3.

[0057] To obtain the seventh shifting condition S7 in the power-split drive train, the shifting element K1 is closed and the two shifting elements K2 and K3 are opened. Thus, rotational speed variability is obtained for the second and third drive output shafts Ab2 and Ab3.

[0058] The four embodiments of the power-split drive train according to the invention illustrated can be simplified, in particular by the omission of shifting elements and the associated omission of shifting conditions. For example, the first additional drive unit 2a shown in FIGS. 1, 2, 4 and 5 can have no shifting element K1, so that the first and second shafts W1 and W2 cannot be coupled to one another. Then, all the shifting conditions in which the shifting element K1 is closed are unavailable.

[0059] Alternatively, the shifting element K1 of the first additional drive unit 2a in FIG. 1 can be arranged between the second shaft W2 and the third shaft W3. Inasmuch as the shifting elements K1, K2, K3 are connected to respective planetary gearsets 4a, 4b, 4c, coupling with two of the three shafts of the planetary gearset 4a, 4b, 4c concerned is possible.

[0060] In the present case the control units for controlling and regulating the energy converters 3a, 3b, 3c are not shown in the figures. In further developments of the embodiments according to the invention, further shiftable and/or non-shiftable transmission stages can be arranged upstream and/or downstream.

[0061] Preferably, the second additional drive unit 2b in FIGS. 1 and 4 comprises the shifting element K2. Further, however, it is also conceivable to omit the shifting element K2 of the second additional drive unit 2b, and the fifth shaft W5 is then connected rotationally fixed to or made integrally with the fourth shaft W4. In that case all the shifting conditions in which K2 is open are unavailable. Furthermore, it is conceivable to omit the fourth shaft W4 and the energy converter 3b of the second additional drive unit 2b is then connected to the second drive output shaft Ab2 by the fifth shaft W5 and by the electric line 5 to the respective energy converter 3a and 3c of the first and third additional drive unit 2a, 2c. All shifting conditions in which K2 is closed are then unavailable.

[0062] Also preferably, the second additional drive unit 2b shown in FIGS. 2 and 5 comprises the shifting element K2. In addition, however, it is also conceivable to omit the shifting element K2 of the second additional drive unit 2b. In that case all shifting conditions in which the shifting element K2 is closed are unavailable.

[0063] Also preferably, the third additional drive unit 2c shown in FIGS. 1 and 2 comprises the first shifting element K3, whereas the second shifting element B1 of the third additional drive unit 2c is omitted. Thus, all the shifting conditions with the second shifting element B1 closed are unavailable. Preferably moreover, the third additional drive unit 2c comprises the second shifting element B1 whereas the first shifting element K3 of the third additional drive unit 2c is omitted. Then, all the shifting conditions with the first shifting element K3 closed are unavailable. The closing of the second shifting element B1 of the third additional drive unit 2c can in particular produce a preferred rotational speed level of the energy converter 3c of the third additional drive unit 2c, whereby a rotational speed is increased and torque is reduced.

[0064] Preferably also, the third additional drive unit 2c according to FIGS. 4 and 5 comprises the first shifting element K3. Further, however, it is also conceivable to omit the first shifting element K3 of the third additional drive unit 2c and the seventh shaft W7 is then connected rotationally fixed to or made integrally with the sixth shaft W6. In that case all shifting conditions with K3 open are unavailable. Furthermore, it is conceivable to omit the sixth shaft W6 and the energy converter 3c of the third additional drive unit 2c is then connected by the seventh shaft W7 to the third drive output shaft Ab3 and by the electric line 5 to the respective energy converter 3a and 3b of the first and second additional drive unit 2a, 2b. All the shifting conditions with K3 closed are then unavailable.

[0065] The example embodiments described enable various operating modes with fully or partially continuously variable drive for the respective drive output shafts Ab1, Ab2, Ab3. An advantage of the example embodiments shown is the very small number of energy converters 3a, 3b, 3c needed, which among other things makes it possible to produce a compactly built and cost-optimized power-split drive train. Owing to the multiple use and synergistic interplay of the three additional drive units 2a, 2b, 2c, depending on the shifting condition three rotation-speed-variable drive output shafts Ab1, Ab2, Ab3 are available.

INDEXES

[0066] 1 Main drive element [0067] 2a First additional drive unit [0068] 2b Second additional drive unit [0069] 2c Third additional drive unit [0070] 3a Energy converter of the first additional drive unit [0071] 3b Energy converter of the second additional drive unit [0072] 3c Energy converter of the third additional drive unit [0073] 4a First planetary gearset of the first additional drive unit [0074] 4b Planetary gearset of the second additional drive unit [0075] 4c Planetary gearset of the third additional drive unit [0076] 5 Electric line [0077] 6 Interface [0078] 7 Housing [0079] 8 Continuous power-split transmission [0080] 9 Energy storage device

[0081] Ab1 First drive output shaft [0082] Ab2 Second drive output shaft [0083] Ab3 Third drive output shaft [0084] K1 Shifting element of the first additional drive unit [0085] K2 Shifting element of the second additional drive unit [0086] K3 First shifting element of the third additional drive unit [0087] B1 Second shifting element of the third additional drive unit [0088] W1 First shaft [0089] W2 Second shaft [0090] W3 Third shaft [0091] W4 Fourth shaft [0092] W5 Fifth shaft [0093] W6 Sixth shaft [0094] W7 Seventh shaft [0095] W8 Eighth shaft [0096] W9 Ninth shaft [0097] S1 First shifting condition [0098] S2 Second shifting condition [0099] S3 Third shifting condition [0100] S4 Fourth shifting condition [0101] S5 Fifth shifting condition [0102] S6 Sixth shifting condition [0103] S7 Seventh shifting condition [0104] S8 Eighth shifting condition [0105] S9 Ninth shifting condition [0106] S10 Tenth shifting condition [0107] S11 Eleventh shifting condition