Hybrid powertrain and method for controlling a powertrain

Abstract

A hybrid powertrain (1) for a motor vehicle, having an internal combustion engine, an electric machine (EM) and a transmission device (5), wherein the transmission device (5) has at least one first planetary gear set (PGS1) and is configured as a main transmission, wherein: a first element of the first planetary gear set (PGS1) can be rotationally connected to the internal combustion engine and can be fixed directly or indirectly relative to the housing, wherein the first element of the first planetary gear set (PGS1) is configured as a ring gear (13); a second element of the first planetary gear set (PGS1) can be rotationally connected to the electric machine (EM) by means of a clutch C and can be fixed directly or indirectly relative to the housing, wherein the second element of the first planetary gear set (PGS1) is configured as a sun gear (11); a third element of the first planetary gear set (PGS1) is connected to a driven device (4), wherein the third element of the first planetary gear set (PGS1) is configured as a planet carrier (12); wherein the ring gear (13) can also be connected to the electric machine (EM) by means of a clutch D; the clutch C has an output disk carrier CA connected to the sun gear (11) of the first planetary gear set (PGS1); the clutch D has an output disk carrier DA connected to the ring gear (13) of the first planetary gear set (PGS1); and the input disk carrier (32) and the output disk carrier DA are rotatably supported relative to each other.

Description

Field of the Invention

[0001] The present invention relates to a hybrid powertrain, in particular a hybrid powertrain for a motor vehicle, which hybrid powertrain has an internal combustion engine, an electric motor and a transmission device. The present invention also relates to a method for controlling a hybrid powertrain. Background Art

[0002] Hybrid powertrains are known from the prior art in many variants. The hybrid powertrain comprises a transmission device in the form of one or more spur gear transmission sets or planetary gear transmission sets, a drive motor, such as an internal combustion engine, and another drive motor, such as an electric motor, such that the respective drive powers of the two machines can be combined or can be transmitted to the driven device individually.

[0003] The internal combustion engine can usually be coupled to the transmission device by means of a starting clutch. In contrast, the attachment of the electric motor to the powertrain can in principle be freely specified.

[0004] If the electric motor is arranged in the power flow between the internal combustion engine and the transmission device or is directly coupled to the transmission shaft of the transmission device, the internal combustion engine gears, i.e., the gears that are in the power flow during pure internal combustion engine operation, can also be used at least in part by the electric motor.

[0005] Another possibility for attaching the electric motor is that the electric motor is directly or via another transmission device coupled to the driven device.

[0006] The attachment can generally be achieved by means of a traction mechanism drive, a spur gear stage or a planetary gear transmission, wherein the gear stage is preferably selected such that the electric motor can operate in an efficient, high speed range by means of said gear stage.

[0007] However, it has proven particularly advantageous for the electric motor to be coupled to the driven device via a main transmission in the form of a planetary gear transmission set, in such a way that a first element of the main transmission is connected to the internal combustion engine, a second element of the main transmission is connected to the electric motor, and a third element of the main transmission is connected to the driven device, as disclosed in document DE 10 2016 221 735 A1. In this situation, the power inputs of the two drive machines meet in the main transmission. The speeds of the two drive machines can be set independently of the respective other drive machine, so that the transmission device can have a driving characteristic similar to that of a continuously variable transmission.

[0008] Basically, the overall transmission includes three elements, namely the sun gear, the planet carrier, and the ring gear. A plurality of planet gears are rotatably supported on the planet carrier, and the plurality of planet gears rotate about their own axes and the axis of the sun gear. It can be freely determined which of the three elements is associated with the sun gear, the planet carrier, or the ring gear. The power inputs of the internal combustion engine and the electric motor are realized at two different elements of the overall transmission and are output via the element of the overall transmission that is connected to the driven device. Thus, for example, the sun gear is connected to the electric motor, the planet carrier is connected to the driven device, and the ring gear is connected to the transmission. Or the sun gear is connected to the driven device, the planet carrier is connected to the transmission, and the ring gear is connected to the electric motor, and so on.

[0009] Document DE10 2018 203 563 describes a powertrain of the above type, which has an electric motor and an internal combustion engine, wherein a transmission connected upstream of the overall transmission in the form of two planetary transmission groups is provided between the overall transmission and the internal combustion engine. Thus, overall, the powertrain includes three planetary transmission groups, by means of which driving programs can be depicted, for example two pure electric gears, four pure internal combustion engine gears, and three hybrid gears. Starting the internal combustion engine by means of the electric motor in a limited manner and taking into account the gear selection or vehicle speed during driving is also feasible.

[0010] DE 10 2015 216 896 A1 shows a drive device for a hybrid vehicle, which has an internal combustion engine and an electric motor as well as a torque superposition device for superposing the torques generated by the internal combustion engine and the electric motor on an output shaft.

[0011] The torque superposition device includes a planetary transmission device having two coupled planetary transmission groups, wherein each planetary transmission group respectively has a ring gear, a sun gear, and a shifting element, wherein the planet carrier of the first planetary transmission group is rotationally coupled to the ring gear of the second planetary transmission group, and wherein the driven shaft is rotationally coupled to the planet carrier of the second planetary transmission group.

[0012] JP 2009-1234 A shows a drive device for a hybrid vehicle, which is provided with a motor, a motor generator, and an automatic transmission, and the drive device has a plurality of input clutches for forming shift stages. The input clutches are composed of an engaging element on the input side that engages with the output shaft of the motor and engaging elements on the output side that are respectively connected to the input elements of the automatic transmission. The rotor of the motor generator is connected to the engaging element on the output side of the input clutch so as to form the lowest speed stage, which engages when setting the lowest speed stage to achieve the maximum shift ratio of the engaging elements so that power can be transmitted.

[0013] DE 11 2006 002 537 B4 shows an electrically adjustable transmission series, which provides a cost-effective electrically adjustable transmission mechanism with a low content. The transmission mechanism includes a first differential gear set and a second differential gear set, a battery, two electric motors that can be interchangeably used as motors or generators, a claw clutch, and four or five optional torque transmission devices. The differential gear set is preferably a planetary gear set, but other gear devices can be used, such as bevel gears or differential gear devices at offset shafts. Summary of the Invention

[0014] However, the aim is to improve this powertrain in terms of structural size and cost, and to increase the number of pure electric gears.

[0015] This object is achieved by a hybrid powertrain, especially for a motor vehicle, which has an internal combustion engine, an electric motor, and a transmission device. The transmission device has at least one first planetary transmission set and is configured as a main transmission, where

[0016] - The first element of the first planetary transmission set is rotationally connected or can be rotationally connected to the internal combustion engine and can be fixed relative to the housing,

[0017] - The second element of the first planetary transmission set can be rotationally connected to the electric motor by means of clutch C and can be fixed relative to the housing,

[0018] - The third element of the first planetary transmission set is connected to the driven device,

[0019] where the first element can also be connected to the electric motor by means of clutch D.

[0020] With the hybrid powertrain according to the invention, the main transmission can either absorb the drive power of the electric motor only via the first element, only via the second element, or simultaneously from both elements and transmit it to the driven device, and three pure electric gears are established. However, in addition, clutches C and D can also be used to transmit the drive power only from the internal combustion engine to the driven device in order to establish gears for internal combustion engine operation. The EVT gears known from the prior art can also be implemented without limitation or the additional use of the electric motor can be achieved in parallel operation with the internal combustion engine. By the feasibility of the multiple uses of the two clutches C and D to achieve gears for electric operation, gears for internal combustion engine operation, and gears for hybrid power operation, not only can the number of gears to be shifted be increased, but also the number of necessary clutches can be reduced or costs can be saved.

[0021] "Rotationally connected" or "rotatably connected" means a torque-coupled connection. "Can be fixed relative to the housing" means a friction-fit or form-fit connection with the housing.

[0022] The first planetary gear transmission set can be configured simply or in the type of a positive planetary gear transmission.

[0023] The first element of the first planetary gear transmission set can either be directly rotationally connected to the internal combustion engine. It is also conceivable to provide a clutch and / or other planetary gear transmission sets for reducing the rotational speed in the power flow between the first element and the internal combustion engine.

[0024] Furthermore, the first element of the planetary gear transmission set can be directly fixed relative to the housing by means of a brake in order to brake the planetary gear transmission set. It is also conceivable that the first element is indirectly fixed relative to the housing, where clutches and brakes of the transmission device are used, which are not directly associated with the first planetary gear transmission set but are provided for controlling, for example, another planetary gear transmission set.

[0025] The second element of the planetary gear transmission set can preferably be directly fixed relative to the housing by means of brake B in order to brake the planetary gear transmission set. It is also conceivable to fix the second element indirectly relative to the housing, where clutches and brakes of the transmission device are used, which are not directly associated with the first planetary gear transmission set but are provided for controlling, for example, another planetary gear transmission set.

[0026] Clutches C and D preferably form a dual-clutch device and have a common clutch input side, where the common clutch input side is rotationally connected to the electric machine. The common clutch input side preferably includes an input disk carrier, which has disks associated not only with clutch C but also with clutch D.

[0027] The clutch input side of the dual-clutch device is preferably connected to the electric machine (EM) via a gear stage, where the gear stage is axially arranged between brake B and the dual-clutch device.

[0028] According to the invention, the first element of the first planetary gear transmission set is configured as a ring gear, the second element of the first planetary gear transmission set is configured as a sun gear, and the third element of the first planetary gear transmission set is configured as a planetary gear carrier.

[0029] Clutch C preferably has an output disk carrier CA connected to the sun gear of the first planetary gear transmission set, where clutch D has an output disk carrier connected to the ring gear of the first planetary gear transmission set, and the input disk carrier and the output disk carrier are rotatably supported relative to each other.

[0030] In the design according to the invention, clutches C and D are radially nested relative to each other in their arrangement. It is also advantageous that clutch D is radially arranged outside clutch C.

[0031] The sun gear of the first planetary transmission stage is preferably configured as a hollow shaft and is rotatably supported relative to the planet carrier of the first planetary transmission stage.

[0032] The planet carrier of the first planetary transmission stage is preferably connected to the output device via a gear stage, wherein the gear stage is arranged on the side opposite the internal combustion engine in the powertrain.

[0033] However, in another advantageous compact design, it is also conceivable to arrange the gear stage axially between the dual clutch device and the first planetary transmission stage, wherein the electric machine is arranged on the side opposite the internal combustion engine in the powertrain.

[0034] Particularly preferably, the transmission device includes a second planetary transmission stage, wherein

[0035] - the planet carrier of the second planetary transmission stage is rotationally connected to the ring gear of the first planetary transmission stage,

[0036] - the sun gear of the second planetary transmission stage is rotationally connected to the internal combustion engine,

[0037] - the ring gear of the second planetary transmission stage can be fixed relative to the housing by means of brake E, and wherein

[0038] - the planet carrier and the sun gear of the first planetary transmission stage can be rotationally connected by means of clutch A.

[0039] By means of the attachment according to the invention of the further planetary transmission stage, three purely electric operating gears, four purely internal combustion engine gears, four hybrid parallel operating gears and two EVT operating gears result during operation.

[0040] The second planetary transmission stage is preferably arranged axially between the internal combustion engine and the first planetary transmission stage.

[0041] The powertrain preferably only includes two planetary transmission stages, namely the first planetary transmission stage and the second planetary transmission stage.

[0042] It is also advantageous that the internal combustion engine is only rotationally connected to the sun gear of the second planetary transmission stage and can also be connected to the planet carrier of the second planetary transmission stage only via clutch A.

[0043] Preferably, the first planetary transmission stage and the second planetary transmission stage are only connected to each other by a torsion-resistant connection between the ring gear of the first planetary transmission stage and the planet carrier of the second planetary transmission stage, such that the second planetary transmission stage is arranged between the first planetary transmission stage and the internal combustion engine in the direction of the power flow - with respect to the drive power of the internal combustion engine.

[0044] The electric machine is preferably arranged parallel to the first planetary gear set and the second planetary gear set.

[0045] In an advantageous method for controlling a powertrain, it is proposed that there is a gear position for pure electric operation, in particular a third gear position for pure electric operation, by closing clutches C and D. By this measure, two elements of the first planetary gear set are indirectly rotationally connected to one another and the planetary gear set is locked. Instead of an additional clutch required for directly coupling the two elements, clutches C and D which are also provided for attachment to the electric machine accordingly can be used.

[0046] Preferably, there is a gear position for pure internal combustion engine operation, in particular a second gear position for pure internal combustion engine operation, by closing clutches C and D and brake E.

[0047] Preferably, a hybrid gear position is engaged, in which the third pure electric gear position and the second internal combustion engine gear position are engaged in combination. Description of the Drawings

[0048] The invention is described below by way of example with reference to the drawings.

[0049] Figure 1 A hybrid powertrain according to the invention according to a first embodiment is shown.

[0050] Figure 2 A shift diagram for a hybrid powertrain according to a first embodiment is shown.

[0051] Figure 3 A hybrid powertrain according to the invention according to a second embodiment is shown.

[0052] Figure 4 A shift diagram for a hybrid powertrain according to a second embodiment is shown. Detailed Description

[0053] The hybrid powertrain 1 shown in Figure 1 has an internal combustion engine (not shown), a dual-mass flywheel, a transmission input shaft 3, a transmission device 5, an electric machine EM, a driven device 4 and a housing.

[0054] The transmission device 5 includes a first planetary gear set PGS1, which in turn has a first element configured as a ring gear 13, a second element configured as a sun gear 11 and a third element configured as a planetary gear carrier 12.

[0055] Furthermore, the transmission device 5 has a second planetary gear set PGS2, which includes a sun gear 21, a planetary gear carrier 22 and a ring gear 23.

[0056] The sun gear 21 is torsionally connected to the internal combustion engine via the transmission input shaft and the dual-mass flywheel. The sun gear 21 can be connected to the planet carrier 22 by means of clutch A, so that the second planetary transmission group PGS2 can be locked. In addition, the ring gear 23 can be fixed relative to the housing by means of brake E, so that the second planetary transmission group PGS2 can operate in a braking state.

[0057] The first planetary transmission group and the second planetary transmission group PGS1, PGS2 are coupled to each other only via a torsional connection between the ring gear 13 and the planet carrier 22. The power flow of the driving power of the internal combustion engine extends via the second planetary transmission group PGS2 towards the ring gear 13 of the first planetary transmission group PGS1.

[0058] The first planetary transmission group PGS1 is configured as a main transmission, i.e., the power inputs of the two drive machines meet in the first planetary transmission group and are output towards the driven device via the planet carrier 12 and the spur gear stage 7. Here, the electric machine EM can be connected to the first planetary transmission group by means of the dual clutch device 30, which includes clutches C and D. By means of clutch C, a torsional connection can be established between the sun gear 11 and the electric machine EM. In addition, the electric machine EM can be connected to the ring gear 13 by means of clutch D.

[0059] The driving power of the electric machine EM is either only introduced into the sun gear 11, only introduced into the ring gear 13, or as long as clutches C and D are closed, it is simultaneously introduced not only into the sun gear 11 but also into the ring gear 13 in the first planetary transmission group.

[0060] If both clutches C and D are closed, the first planetary transmission group PGS1 is in a locked state.

[0061] Clutches C and D have a common clutch input side 31, where the common clutch input side 31 is rotationally connected to the electric machine EM. In addition, the common clutch input side 31 includes an input disk carrier 32, which carries disks associated with both clutch C and clutch D.

[0062] In addition, the clutch input side 31 is rotationally connected to the electric machine EM via the gear stage 6, where the electric machine is arranged parallel to the transmission device.

[0063] By means of brake B, the sun gear 11 can be directly fixed relative to the housing, whereby the first planetary transmission group can operate in a braking state.

[0064] Here, the gear stage 6 is axially arranged between the brake B and the dual clutch device.

[0065] In the embodiment, a gear stage 7 that rotationally connects the planet carrier to the driven device 4 is provided on a side of the hybrid powertrain 1 opposite to the internal combustion engine.

[0066] The hybrid powertrain 1 is configured to establish four pure internal combustion engine gears. In the hybrid powertrain, a first planetary transmission group and a second planetary transmission group (PGS1 and PGS2) operate in a combination formed by block surrounding and circumferential transmission. Thus, for example, if the brakes B and E are closed, that is, the two planetary transmission groups PGS1 and PGS2 are braked and rotate with their circumferential transmission, then the first internal combustion engine gear is engaged according to the Figure 2 shift diagram in. In the second internal combustion engine gear, the two clutches C and D are closed, so that the first planetary transmission group is locked. In contrast, the second planetary transmission group PGS2 remains in the braked state.

[0067] In addition, the hybrid powertrain 1 is configured to support the four internal combustion engine gears by turning on the electric machine EM in parallel operation or drive the four internal combustion engine gears in the energy recovery mode. Here, if the clutch D has not already been used for the internal combustion engine gear according to the Figure 2 shift diagram in, then the clutch D is additionally closed.

[0068] There are a first electrically operated gear and a second electrically operated gear, in which one of the two clutches C or D is closed, and at the same time the first planetary transmission group PGS1 is in the braked state.

[0069] The braked state can be achieved directly or indirectly. If the ring gear 13 is to be driven by the machine EM (second electrically operated gear), the first planetary transmission group PGS1 is directly braked by the brake B, and in the first planetary transmission group, the sun gear 11 is fixed relative to the housing. In contrast, if the sun gear 11 is to be driven by the electric machine EM (first electrically operated gear), the first planetary transmission group PGS1 is indirectly braked by fixing the ring gear 13 relative to the housing by means of the brake E and the clutch A, where the brake E and the clutch A are not directly associated with the first planetary transmission group, but with the second planetary transmission group.

[0070] According to the invention, a third purely electrically operated gear is established by closing the clutches C and D.

[0071] Another feature of the hybrid powertrain 1 is the feasibility of operating the two drive machines at different speeds in a so-called EVT mode. In the stepless operation, the electric machine is only attached to the sun gear 11 via the clutch C. In contrast, the power of the internal combustion engine flows into the ring gear 13. Thus, the first planetary transmission group remains unbraked.

[0072] Therefore, during operation, a total of three pure - electric gears, four pure - internal - combustion gears, four hybrid - parallel - operation gears, and two EVT - operation gears are obtained.

[0073] The Figure 3 hybrid powertrain 1 shown in Figure 1 shows a second embodiment and basically includes the same components and a similar structure as the first embodiment shown in

[0074] , and thus the same reference numerals are used correspondingly. The main differences are shown in the attachment of the two drive machines and the driven device to the first planetary transmission set / main transmission. Therefore, the first element of the first planetary transmission set is associated with the ring gear 11. The second element is associated with the planetary carrier 12, and the third element is associated with the ring gear 13.

[0074] In addition, the first planetary transmission set PGS1 is configured as a positive planetary transmission.

[0075] In addition, the gear stage 6 is arranged on the side opposite to the internal combustion engine in the hybrid powertrain. In contrast, the gear stage 7 is arranged between the dual - clutch device 30 and the first planetary transmission set PGS1.

[0076] The working mode is the same as that of the first embodiment. Therefore, the types and numbers of gears remain the same respectively. Due to the different attachments of the drive machine and the driven device to the first planetary transmission set PGS1, a shorter transmission ratio of the first gear is obtained, thereby improving the expansion. The Figure 4 operation - optimized shift logic is known from

[0077] List of Reference Numerals

[0078] 1 Powertrain

[0079] 3 Transmission input

[0080] 4 Driven device

[0081] 5 Transmission device

[0082] 6 Gear stage

[0083] 7 Gear stage

[0084] 11 Sun gear of the first planetary transmission set

[0085] 12 Planetary carrier of the first planetary transmission set

[0086] 13 Ring gear of the first planetary transmission set

[0087] 21 Sun gear of the second planetary transmission set

[0088] 22 Planetary carrier of the second planetary transmission set

[0089] 23 Ring gear of the second planetary transmission set

[0090] 30 Dual clutch device

[0091] 31 Clutch input side

[0092] 32 Input disk carrier

[0093] CA Output disk carrier of clutch C

[0094] CD Output disk carrier of clutch D

[0095] EM Electric motor

[0096] PGS1 First planetary transmission set

[0097] PGS2 Second planetary transmission set

[0098] A Clutch

[0099] B Brake

[0100] C Clutch

[0101] D Clutch

[0102] E Brake

Claims

1. A hybrid powertrain (1) for a motor vehicle, the hybrid powertrain having an internal combustion engine, an electric machine (EM) and a transmission device (5), wherein the transmission device (5) has at least a first planetary transmission set (PGS1) and is configured as a main transmission, wherein - a first element of the first planetary transmission set (PGS1) can be rotationally connected to the internal combustion engine and can be fixed directly or indirectly relative to the housing, wherein the first element of the first planetary transmission set (PGS1) is configured as a ring gear (13), - a second element of the first planetary transmission set (PGS1) can be rotationally connected to the electric machine (EM) by means of a clutch C and can be fixed directly or indirectly relative to the housing, wherein the second element of the first planetary transmission set (PGS1) is configured as a sun gear (11), - a third element of the first planetary transmission set (PGS1) is connected to a driven device (4), wherein the third element of the first planetary transmission set (PGS1) is configured as a planet carrier (12), - wherein the ring gear (13) can also be connected to the electric machine (EM) by means of a clutch D, characterized in that, The clutch C has an output disk carrier CA connected to the sun gear (11) of the first planetary transmission set (PGS1), wherein the clutch D has an output disk carrier DA connected to the ring gear (13) of the first planetary transmission set (PGS1), and wherein the input disk carrier (32) and the output disk carrier DA are rotatably supported relative to each other, wherein the clutch C and the clutch D form a dual clutch device (30) and have a common clutch input side (31), wherein the common clutch input side is rotationally connected to the electric machine (EM), wherein the common clutch input side (31) includes an input disk carrier which carries disks associated not only with the clutch C but also with the clutch D, wherein the second element of the planetary transmission set can be fixed relative to the housing by means of a brake B, and the clutch input side (31) of the dual clutch device is connected to the electric machine (EM) via a gear stage (6), wherein the gear stage (6) is axially arranged between the brake B and the dual clutch device.

2. The powertrain according to claim 1, characterized in that The sun gear (11) of the first planetary transmission set (PGS1) is configured as a hollow shaft and is rotatably supported relative to the planet carrier (12) of the first planetary transmission set (PGS1).

3. The powertrain according to claim 1, characterized in that The planet carrier (12) of the first planetary transmission set (PGS1) is connected to the driven device (4) via a gear stage (7), wherein the gear stage (7) is arranged on a side opposite to the internal combustion engine in the powertrain (1).

4. The powertrain according to claim 1, characterized in that, The transmission device (5) further includes a second planetary transmission set (PGS2), wherein - the planet carrier (22) of the second planetary transmission set (PGS2) is rotationally connected to the ring gear (13) of the first planetary transmission set (PGS1), - wherein the sun gear (11) of the second planetary gear set (PGS2) is rotationally connected to the internal combustion engine, - the ring gear (23) of the second planetary gear set (PGS2) can be fixed relative to the housing by means of brake E, and - wherein the planet carrier (12) and the sun gear (11) of the first planetary gear set (PGS1) can be rotationally connected by means of clutch A.

5. The powertrain according to claim 4, characterized in that, The powertrain (1) includes only two planetary gear sets (PGS1 and PGS2).

6. The powertrain according to claim 4, characterized in that, The internal combustion engine is rotationally connected only to the sun gear (21) of the second planetary gear set (PGS2), and moreover is connected only to the planet carrier (22) of the second planetary gear set (PGS2) via the clutch A.

7. The powertrain according to claim 4, characterized in that, The first planetary gear set and the second planetary gear set (PGS1 and PGS2) are connected to each other only by a torsion-resistant connection between the ring gear (13) of the first planetary gear set (PGS1) and the planet carrier (22) of the second planetary gear set (PGS2).

8. A method for controlling a powertrain according to claim 1, characterized in that, A third all-electric gear is provided by closing the clutch C and the clutch D.

9. The method for controlling a powertrain according to claim 8, characterized in that, A second pure internal combustion engine gear is provided by closing the clutch C and the clutch D and the brake E.

10. The method for controlling a powertrain according to claim 8, characterized in that, A hybrid gear is provided, in which the third all-electric gear and the second pure internal combustion engine gear are engaged combinatorially.

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