Method and control device for operating a drive train

Abstract

A method for operating a drive train of a motor vehicle, which comprises an internal combustion engine (1), an electrical machine (4), and a range change transmission (2) having a main transmission (9) and a range change group (11), wherein the internal combustion engine (1) is coupled via a switchable separating clutch (5) to an input shaft (6) of the range change transmission (2), and wherein the electrical machine (4) is also coupled to the input shaft (6). In the event that the motor vehicle is traveling with the separating clutch engaged, an upshift is to be carried out with the involvement of the range change group (11) and the main transmission (9), and the electrical machine (4) cannot be used for shifting element synchronization, the following is carried out: the motor vehicle is braked such that a rotational speed of the internal combustion engine (1) is brought to a target rotational speed. Subsequently, a load on a shifting element of the range change group (11) to be disengaged is reduced to carry out the upshift, and said element is disengaged. Subsequently, the input shaft (6) of the range change transmission is synchronized to a first target rotational speed, and then the shifting element of the range change group (11) to be engaged in order to carry out the upshift is engaged. At an overlapping moment in time or subsequently, the main transmission (9) is shifted into neutral, the input shaft (6) is synchronized to a second target rotational speed, and a shifting element of the main transmission (9) to be engaged in order to carry out the upshift is engaged.

Description

[0001] ZF Friedrichshafen AG File 305279 Friedrichshafen 2024-10-30

[0002] Method and control unit for operating a drive train

[0003] The invention relates to a method for operating the drivetrain of a motor vehicle, wherein the drivetrain comprises an internal combustion engine as the first drive unit, an electric machine as the second drive unit, and an automated transmission group connected between the drive units and an output shaft, wherein the internal combustion engine is coupled to an input shaft of the transmission group via a switchable disconnect clutch, wherein the electric machine is also coupled to the input shaft of the transmission group, and wherein the transmission group comprises several sub-transmissions, namely at least one main transmission and a range group connected downstream of the main transmission. The invention further relates to a control unit for operating such a drivetrain.

[0004] DE 10 2007 043 694 A1 discloses a group transmission comprising a main transmission, a range group connected downstream of the main transmission, and a splitter group connected upstream of the main transmission. The main transmission and splitter group are designed as reduction gears with countershafts, one of which has a transmission brake engaged. An internal combustion engine is coupled to an input shaft of the group transmission via a disconnect clutch, and an output shaft is coupled to an output shaft of the group transmission. Shifting is possible within the group transmission, and according to DE 10 2007 043 694 A1, the transmission brake is used to synchronize the shifting elements.

[0005] DE 10 2013 211 225 A1 discloses a group transmission for a motor vehicle, which in turn comprises a main transmission, a range group connected downstream of the main transmission, and a splitter group connected upstream of the main transmission, wherein an internal combustion engine and an electric machine are coupled to the input shaft of the group transmission. The internal combustion engine is coupled to the input shaft of the group transmission via a disconnect clutch, while the electric machine is permanently coupled to the input shaft of the group transmission via a planetary gear stage. ZF Friedrichshafen AG File 305279 Friedrichshafen 2024-10-30

[0006] The group transmission for a hybrid drive arrangement disclosed in DE 10 2013 211 225 A1 does not include a transmission brake. In one version, the electric machine is used to synchronize the switching elements.

[0007] If the electric machine for synchronizing the switching elements is unavailable, for example due to a malfunction or failure of a high-voltage system, it is currently not reliably possible to perform shifts in the transmission. This can then lead to the vehicle breaking down.

[0008] Based on this, there is a need for a method for operating a motor vehicle drive train with an automated group transmission, in which an upshift can be reliably carried out even when the electric machine cannot be used for shift element synchronization, with the involvement of the range group and the main transmission.

[0009] The invention is based on the objective of creating a novel method for operating a drive train of a motor vehicle and a control unit for carrying out the method.

[0010] This problem is solved by a method for operating a drive train according to claim 1 and by a control unit according to claim 9.

[0011] Then, when the vehicle is driving with the disconnect clutch engaged, and an upshift is to be performed in the range transmission, at least involving the range group and the main transmission, and the electric machine cannot be used for shift element synchronization, the following steps are carried out to perform the upshift:

[0012] The vehicle is braked in such a way that the combustion engine speed is reduced to a target speed. ZF Friedrichshafen AG File 305279 Friedrichshafen 2024-10-30

[0013] Subsequently, a load reduction is carried out on a positive-locking switching element of the area group designed to execute the up-switching operation, and the same element is then designed to bring the area group into neutral.

[0014] Subsequently, the input shaft is synchronized to a first target speed, and then the positive-locking switching element of the range group, which is to be inserted to execute the upshift, is inserted.

[0015] Simultaneously with the insertion of the positive-locking switching element of the range group or subsequently thereafter, the main gearbox is moved into neutral, subsequently the input shaft is synchronized to a second target speed and a positive-locking switching element of the main gearbox to be inserted for the execution of the upshift is inserted.

[0016] The invention enables reliable upshifting in the range transmission even when the range transmission has neither a transmission brake nor can the electric motor be used for shift element synchronization. The upshift occurs at a relatively low engine speed to ensure the smallest possible speed differential at the shift element to be closed for the upshift in the range group. Synchronization does not utilize the engine braking system of the combustion engine.

[0017] Preferably, when the vehicle decelerates, the internal combustion engine's speed is reduced to a minimum speed that corresponds to the engine's idle speed increased by a predetermined offset and multiplied by the gear ratio of the upshift to be performed, or to a speed dependent on this, which is greater than the minimum speed by an offset or factor. Such an engine speed, to which the vehicle is brought during deceleration, is preferred in order to ensure that the upshift can be reliably executed within a relatively short shift time with the smallest possible differential speed at the switching element of the range group to be closed, and to still provide sufficient torque reserve adapted to the current driving situation. ZF Friedrichshafen AG File 305279 Friedrichshafen 2024-10-30

[0018] Preferably, the synchronization of the input shaft of the group transmission to the first target speed is achieved via friction losses of the group transmission and / or the internal combustion engine.

[0019] First, the disconnect clutch is held closed, and then, when the input shaft of the range gearbox reaches the first target speed before the internal combustion engine reaches its idle speed, the positive-locking switching element of the range group to be engaged for upshifting is activated.

[0020] However, if the internal combustion engine reaches its idle speed before the input shaft of the range gearbox reaches the first target speed, the disconnect clutch is opened, and then, if the input shaft of the range gearbox subsequently reaches the first target speed, the positive-locking switching element of the range group to be engaged for the execution of the upshift is activated, and after the positive-locking switching element of the range group to be engaged for the execution of the upshift is engaged, the disconnect clutch is closed again.

[0021] Then, if the input shaft of the group transmission reaches the first target speed before the internal combustion engine reaches its idle speed, the disconnect clutch can be kept closed and the synchronization of the input shaft of the group transmission to the first target speed takes place via friction losses or drag losses of the group transmission and internal combustion engine.

[0022] If, however, the combustion engine reaches its idle speed before the input shaft of the transmission has been synchronized, the disconnect clutch is opened to prevent intervention by the combustion engine's idle speed governor. After the disconnect clutch opens, the transmission's input shaft is synchronized via the transmission's friction losses and no longer via the combustion engine's friction losses. ZF Friedrichshafen AG File 305279 Friedrichshafen 2024-10-30

[0023] Preferably, when the upshift operation also involves a splitter group upstream of the main transmission, a positive-locking switching element designed for upshifting is installed in the splitter group after the main transmission has been shifted into neutral and before the input shaft has been synchronized to the second target speed. This allows the splitter group to be advantageously integrated into the shift mechanism during upshifting.

[0024] Preferably, the upshift is executed when, after a request for upshifting is received, it is determined, based on a current and / or future driving situation, in particular driving resistance and / or road gradient, that the upshift can be performed by the electric motor without synchronization of the switching elements. This further development of the invention is based on the understanding that the upshift should only be performed if, after a request for upshifting is received, it is determined, based on the current and / or future driving situation, that the upshift can actually be performed by the electric motor without synchronization of the switching elements. If, upon a request for upshifting, it is determined that this is not possible, the execution of the upshift is then prevented.

[0025] Preferred embodiments are described in the dependent claims and the following description. Exemplary embodiments of the invention are explained in more detail with reference to the drawing, without being limited thereto. The drawing shows:

[0026] Fig. 1 shows an exemplary scheme of a motor vehicle powertrain, namely a hybrid drive arrangement with a group transmission;

[0027] Fig. 2 is a signal flow diagram to illustrate the invention.

[0028] The present invention relates to a method for operating the powertrain of a motor vehicle with a hybrid drive and an automated transmission, and to a control device for carrying out the method. ZF Friedrichshafen AG File 305279 Friedrichshafen 2024-10-30

[0029] Fig. 1 shows a scheme of a motor vehicle drive train with a first drive unit designed as an internal combustion engine 1, with an automated group transmission 2, with an output 3 and with a second drive unit designed as an electric machine 4.

[0030] The internal combustion engine 1 is coupled to an input shaft 6 of the transmission 2 via a disconnect clutch 5, also referred to as a starting clutch. The disconnect clutch 5 is a friction-based switching element. When the disconnect clutch 5 is open, the internal combustion engine 1 is disengaged from the input shaft 6 of the transmission 2. When the disconnect clutch 5 is closed, either fully or partially closed, the internal combustion engine 1 is coupled to the input shaft 6 of the transmission 2.

[0031] In the illustrated embodiment, the electric machine 4 is permanently coupled to the input shaft 6 of the transmission 2, specifically via a planetary gear 30 as shown in Fig. 1. In addition to the planetary gear 30, a disconnect clutch (not shown) can also be connected between the electric machine 4 and the input shaft 6 of the transmission 2. The output 3 is coupled to an output shaft 8 of the transmission 2.

[0032] In the illustrated embodiment, the group transmission 2 comprises a main transmission 9, a split group 10 upstream of the main transmission 9 in terms of drive technology, and a range group 11 downstream of the main transmission 9 in terms of drive technology.

[0033] The main transmission 9 is also referred to as the main group. The main transmission 9 of the group transmission 2 is designed as a direct-drive transmission with a reduction gear and has two countershafts 21 and 22. In the illustrated embodiment, the main transmission 9 has three gear ratios G1, G2, and G3 for forward travel and one gear ratio R for reverse travel. The loose gears of the gear ratios G1, G2, and R are each rotatably mounted on a main shaft and can be switched via associated switching elements 15, 16, 18, and 19, which are designed as positive-locking claw switching elements. In Fig. 1, switching element 15 is designated as switching element C, switching element 16 as switching element D, switching element 18 as switching element E, and switching element 19 as switching element F. ZF Friedrichshafen AG File 305279 Friedrichshafen 2024-10-30

[0034] The associated fixed gears are arranged rotationally on the countershafts 21, 22. The two switching elements 15, 16 or C, D and the two switching elements 18, 19 or E, F each form a switching package 17 or 20.

[0035] The splitting unit 10 of the transmission group 2, which is upstream of the main transmission 9, is designed in two stages in the illustrated embodiment and is also of a reduction gear design, with the two gear ratios K1 and K2 of the splitting unit 10 forming two switchable input constants of the main transmission 9. The two gear ratios K1 and K2 have a smaller gear ratio difference. The splitting unit 10 of the transmission group 2 is optional and can also be omitted. The loose gear of the first gear ratio K1 is rotatably mounted on the input shaft 6. The loose gear of the second gear ratio K2 is rotatably mounted on the main shaft. The fixed gears of both gear ratios K1 and K2 of the splitting unit 10 are each rotationally fixed to the input-side extended reduction shafts 21 and 22 of the main transmission 9. Synchronized switching elements 12 and 13, so-called synchronous switching elements, of the splitting unit 10 are combined into a common switching assembly 14.In Fig. 1, switching element 12 is designated as switching element A and switching element 13 as switching element B. Switching elements 12 and 13 are designed as positive-locking claw switching elements.

[0036] The range group 11 of the range gearbox 2, which is connected downstream of the main gearbox 9, is also designed as a two-stage gearbox, but as a planetary gearbox 24. The sun gear 25 is non-rotatably connected to the main shaft of the main gearbox 9, which is extended on the output side. The planet carrier 27 is non-rotatably coupled to the output shaft 8 of the range gearbox 2. The ring gear 26 is connected to a shift assembly 23 with two synchronized shift elements 28, 29, by which the range group 11 can be alternately shifted into a low-speed stage by connecting the ring gear 26 to a stationary housing part 7 and into a high-speed stage by connecting the ring gear 26 to the planet carrier 27. In Fig.

[0037] In section 1, switching element 28 is designated as switching element G and switching element 29 as switching element H. Switching elements 28 and 29 are designed as positive-locking claw switching elements. ZF Friedrichshafen AG File 305279 Friedrichshafen 2024-10-30

[0038] In Fig. 1, an optional oil pump 31 engages the countershaft 22 and can be driven from the countershaft 22.

[0039] It should be noted here that the embodiment of the group transmission 2 shown in Fig. 1 is preferred, but optional. The invention can also be used in conjunction with other group transmissions.

[0040] The present invention relates to a method by which it is possible to reliably execute a shift, namely an upshift, at least with the involvement of the range group 11 and the main transmission 9, in a range transmission 2, which is part of a hybrid powertrain configuration of a motor vehicle, and in which, due to the absence of a transmission brake, the electric machine 4 is used for synchronizing shift elements, even when, for example, the electric machine 4 cannot be used for shift element synchronization due to a fault or failure of a high-voltage system. The invention is described in detail below with reference to the range transmission 2 shown in Fig. 1.

[0041] In the initial state of the drivetrain, the vehicle is in motion and a gear is engaged in group transmission 2. The disconnect clutch 5 is closed.

[0042] For example, if, based on driver input of the accelerator pedal, it is determined that the driver desires an upshift, then, preferably based on a current and / or future driving situation, in particular driving resistance and / or road gradient, a check is performed to determine whether the upshift can be executed without synchronization of the switching elements by the electric motor 4. This is intended to ensure that, when an upshift is desired, the upshift is only initiated if there is a sufficient probability that it can actually be executed successfully without assistance from the electric motor 4 for synchronization of the switching elements involved. ZF Friedrichshafen AG File 305279 Friedrichshafen 2024-10-30

[0043] To determine driving resistance and / or road gradient, sensors installed in the drivetrain, such as tilt sensors, as well as models for calculating or estimating the vehicle mass, can be used. Furthermore, GPS data about the road ahead can be provided by a GPS system. Based on these input parameters, driving resistance and / or road gradient can be determined in order to estimate, depending on these parameters, whether a downshift can be performed when a downshift is requested, specifically when the electric motor 4 is not available for synchronizing the shift element.

[0044] If, upon request for upshifting, it is determined that the upshift can be performed by the electric machine 4 without shift element synchronization, the vehicle is decelerated so that the speed of the internal combustion engine 1 is reduced to a target speed. With the disconnect clutch 5 engaged, the speed of the input shaft 6 of the transmission 2 corresponds to the speed of the internal combustion engine 1.

[0045] When the vehicle decelerates, the speed of the internal combustion engine 1 is preferably reduced to a minimum speed, where this minimum speed corresponds to the idle speed of the internal combustion engine 1 increased by a predetermined offset and multiplied by the gear ratio of the upshift to be performed. Alternatively, the speed of the internal combustion engine 1 is reduced to a speed dependent on this minimum speed, which is greater than the minimum speed by an offset or a factor.

[0046] This preconditioning of the powertrain is intended to ensure that the positive-locking switching element of range group 11, which is used to execute the upshift, has the smallest possible differential speed. This allows it to be synchronized relatively quickly to guarantee a relatively short shift time without accessing the engine braking system of the internal combustion engine 1, while ensuring that sufficient torque reserves, adapted to the driving situation, are available from the internal combustion engine 1. ZF Friedrichshafen AG File 305279 Friedrichshafen 2024-10-30

[0047] After the speed of the internal combustion engine 1 has been brought to the defined target speed, a load reduction subsequently takes place on the positive-locking switching element of the range group 11, which is to be designed for the execution of the upshift, by reducing the torque provided by the internal combustion engine 2, preferably while maintaining its speed, whereby the positive-locking switching element of the range group, which is to be designed for the execution of the upshift, becomes load-free and can subsequently be designed to bring the range group 11 into neutral.

[0048] After the range group 11 has been switched to neutral, the input shaft 6 of the range gearbox 2 is subsequently synchronized to a first target speed. This is done without the involvement of the electric machine 4 and without the involvement of a gearbox brake, which is not present in the range gearbox 2 of Fig. 1 anyway. Furthermore, this is done without access to a braking device of the internal combustion engine 1, i.e., without its engine braking system.

[0049] To synchronize the input shaft 6 of the range gearbox 2 to the first target speed, friction losses and / or drag losses of the range gearbox 2 and / or the internal combustion engine 1 are utilized. Initially, the disconnect clutch 5 is held closed. Then, when the input shaft 6 of the range gearbox 2 reaches the first target speed with the disconnect clutch 5 closed, before the internal combustion engine 1 reaches its idle speed, the positive-locking shift element of range group 11, required for upshifting, is activated. This synchronization of the input shaft 6 of the range gearbox 2 with the disconnect clutch closed utilizes friction losses and drag losses of the range gearbox 2 and the internal combustion engine 1.

[0050] However, if the internal combustion engine 1 reaches its idle speed before the input shaft 6 of the transmission 2 has reached its first target speed and thus been synchronized, the disconnect clutch 5 opens to decouple the internal combustion engine 1 from the input shaft 6 of the transmission 2 and to prevent the idle speed governor of the internal combustion engine 1 from becoming active and engaging. ZF Friedrichshafen AG File 305279 Friedrichshafen 2024-10-30

[0051] With the disconnect clutch 5 open, the synchronization of the transmission input shaft 6 is based solely on friction and drag losses of the range transmission 2. When the input shaft 6 of the range transmission 2 has reached the first target speed, the positive-locking shift element of range group 1 1, which is to be engaged for upshifting, is actuated to engage it by ratcheting. For this purpose, the differential speed at the positive-locking shift element of range group 1 1 to be engaged must be less than 300 rpm, preferably in a range between 200 and 300 rpm.

[0052] If the disconnect clutch 5 was opened to synchronize the input shaft 6 of the group transmission 2 to the first target speed, it can be closed again after the positive-locking switching element to be closed for the execution of the upshift in the range group 11 has been engaged.

[0053] By synchronizing the input shaft 6 of the group transmission 2 to the first target speed, the positive-locking switching element of the range group 11 to be engaged for the execution of the upshift is synchronized in order to subsequently be able to engage it by targeted ratcheting and to keep the ratcheting as short as possible.

[0054] Simultaneously with the insertion of the positive-locking switching element of range group 11 for upshifting, or alternatively following the insertion of the positive-locking switching element of range group 11 for upshifting, the main transmission 9 is shifted into neutral by opening a positive-locking switching element in the main transmission 9 designed for upshifting. With the main transmission in neutral, the input shaft 6 of the range transmission 2 can then be synchronized to a second target speed via the internal combustion engine 1 in order to synchronize the positive-locking switching element of the main transmission 9 for upshifting and subsequently insert it. For this purpose, the speed of the internal combustion engine 1 is preferably increased. ZF Friedrichshafen AG File 305279 Friedrichshafen 2024-10-30

[0055] If the upshift operation also involves the splitter group 10 upstream of the main gearbox 9, the splitter group 10 is switched after the main gearbox 9 has been shifted into neutral and before the input shaft 6 of the range gearbox 2 has been synchronized to the second target speed. This is done by disengaging a positive-locking switching element of the splitter group 10 designed for upshifting and inserting a positive-locking switching element of the splitter group 10 designed for upshifting. Only then is the input shaft 6 of the range gearbox 2 synchronized to the second target speed and the positive-locking switching element in the main gearbox 9 designed for upshifting engaged.

[0056] The inventive method is described below with reference to Fig. 2 for an upshift from gear 6 to gear 7, wherein in gear 6 the switching element B is inserted in the split group 11, the switching element C is inserted in the main transmission 9 and the switching element H is inserted in the range group 11, whereas in gear 7, into which the upshift is to be performed from gear 6, the switching element A is inserted in the split group 11, the switching element E is inserted in the main transmission 9 and the switching element G is inserted in the range group 11.

[0057] Block 32 corresponds to an initial state of the drivetrain in which the vehicle is traveling with the disconnect clutch 5 engaged and in which gear 6 is selected in the transmission 2, i.e., the shift elements B, C, and H are closed. During travel, Block 32 detects that an upshift request exists and that this upshift request can be executed by the electric motor 4 even without shift element synchronization.

[0058] In block 33, the drivetrain is preconditioned by braking the vehicle to bring the speed of the internal combustion engine 1 down to the target speed described above, which corresponds to or depends on a minimum speed. The minimum speed is the idle speed of the internal combustion engine, increased by a predetermined offset and multiplied by the gear ratio of the upshift to be performed. ZF Friedrichshafen AG File 305279 Friedrichshafen 2024-10-30

[0059] Subsequently, in block 34, a load reduction takes place on the positive-locking switching element to be designed in area group 11, i.e., for the upshift from gear 6 to gear 7, a load reduction takes place on the switching element H of area group 11, so that in block 34 the switching element H can be designed and the area group can be switched to neutral.

[0060] Subsequently, in block 35, the input shaft 6 of the group gearbox 2 is synchronized to the first target speed. This is achieved, as already explained above, by utilizing friction losses or drag losses of the group gearbox 2 and / or the internal combustion engine 1.

[0061] The signal flow diagram in Fig. 2 shows the variant for synchronizing the input shaft 6 of the transmission 2 to the first target speed at which the internal combustion engine 1 reaches its idle speed before the input shaft 6 of the transmission 2 reaches the first target speed. Thus, in Fig.2 in a block 36 the disconnect clutch 5 is opened in order to subsequently, according to block 37 following the synchronization of block 35, in which friction losses and drag losses of the group transmission 2 and the internal combustion engine 1 are used to synchronize the input shaft 6, to synchronize the input shaft 6 exclusively using friction losses and drag losses of the group transmission 2, until a differential speed is present at the positive-locking switching element to be inserted for the execution of the upshift, i.e. at the switching element G of the range group 11, which reliably allows the switching element G to engage within a short time.

[0062] The engagement of the positive-locking switching element G, which is to be closed for the execution of the upshift in range group 11, is visualized in Fig. 2 by block 38, wherein, as already mentioned, a differential speed in a range between 200 and 300 rpm is preferably set on the positive-locking switching element G of range group 1 by synchronizing the input shaft 6. The switching element G is inserted in block 39, so that range group 11 is again frictionally locked. ZF Friedrichshafen AG File 305279 Friedrichshafen 2024-10-30

[0063] According to block 40, the main gearbox 9 is shifted into neutral either simultaneously with or immediately following the engagement of the shift element G by disengaging the shift element C in the main gearbox 9. Subsequently, in block 41, the disconnect clutch 5, previously opened in block 36, is closed again.

[0064] When shifting from gear 6 to gear 7, a changeover in split group 10 is also required, for which switching element B is deployed and switching element A is inserted in split group 10. This takes place in block 42 in the signal flow diagram of Fig. 2.

[0065] After switching the split group 10 according to block 42, the speed of the input shaft 6 of the group gearbox 2 is synchronized to the second target speed in block 43 by accelerating it using the internal combustion engine 1.

[0066] After the speed of the input shaft 6 of the group transmission 2 has been synchronized to the second target speed, the positive-locking switching element of the main transmission 9, which is to be closed for the execution of the upshift, is closed and thus engaged according to block 44, in the case of a gear change from gear 6 to gear 7, the switching element E of the main transmission 9, so that then in block 45 the gear 7 is engaged and the vehicle is driving in gear 7.

[0067] As previously explained, block 42 is optional. Therefore, when shifting up, for example from gear 5 (with shift elements A, C, and H engaged) to gear 7 (with shift elements A, E, and G engaged), no change in split group 10 is required. Similarly, when shifting from gear 3 (with shift elements A, D, and H engaged) to gear 7 (with shift elements A, E, and G engaged), no change in split group 10 is required.

[0068] Blocks 36, 37, and 40 are only used when the disconnect clutch 5 needs to be opened to synchronize the input shaft 6 of the group transmission 2 to the first target speed. ZF Friedrichshafen AG File 305279 Friedrichshafen 2024-10-30

[0069] The invention further relates to a control unit configured to automatically execute the method described above. The control unit comprises hardware and software means for this purpose. The hardware means include data interfaces for exchanging data with the assemblies involved in carrying out the method according to the invention, for example, for controlling the internal combustion engine 1 and the switching elements involved in performing the upshift. The hardware means also include a processor for data processing and a memory for data storage. The software means include program modules implemented in the control unit for carrying out the method.

[0070] ZF Friedrichshafen AG File 305279 Friedrichshafen 2024-10-30

[0071] Reference mark

[0072] 1 Internal combustion engine

[0073] 2-group gearbox

[0074] 3 Drive

[0075] 4 electric machine

[0076] 5 Disconnect coupling

[0077] 6 Input wave

[0078] 7 Housing part

[0079] 8 Output wave

[0080] 9 Main gearboxes

[0081] 10 Split group

[0082] 11 Area Group

[0083] 12 Synchronous switching element

[0084] 13 Synchronous switching element

[0085] 14 shift package

[0086] 15 switching element

[0087] 16 switching element

[0088] 17 shift package

[0089] 18 switching element

[0090] 19 Switching element

[0091] 20 shift package

[0092] 21 Countershaft

[0093] 22 Countershaft

[0094] 23 Shift package

[0095] 24 planetary gears

[0096] 25 sun wheel

[0097] 26 Ring gear

[0098] 27 planetary carriers

[0099] 28 switching element

[0100] 29 Switching element

[0101] 30 planetary gears

[0102] 31 Oil pump

[0103] 32 Block ZF Friedrichshafen AG File 305279 Friedrichshafen 2024-10-30

[0104] Block 33

[0105] Block 34

[0106] 35 Block

[0107] 36 Block

[0108] Block 37

[0109] 38 Block

[0110] Block 39

[0111] 40 blocks

[0112] Block 41

[0113] 42 Block

[0114] Block 43

[0115] 44 Block

[0116] 45 Block

Claims

ZF Friedrichshafen AG File 305279 Friedrichshafen 2024-10-30 Patent claims 1. A method for operating a drivetrain of a motor vehicle, wherein the drivetrain comprises an internal combustion engine (1) as the first drive unit, an electric machine (4) as the second drive unit, and an automated transmission (2) connected between the drive units and an output (3), wherein the internal combustion engine (1) is coupled to an input shaft (6) of the transmission (2) via a switchable disconnect clutch (5), wherein the electric machine (4) is also coupled to the input shaft (6) of the transmission (2), wherein the transmission (2) comprises several sub-transmissions, namely at least one main transmission (9) and a range group (11) connected downstream of the main transmission (9), characterized in that when the motor vehicle is driving with the disconnect clutch (5) engaged,In the group transmission (2), an upshift is to be carried out at least with the involvement of the range group (11) and the main transmission (9), and the electric machine (4) cannot be used for shift element synchronization. The following steps are carried out to execute the upshift: the vehicle is braked in such a way that the speed of the internal combustion engine (1) is brought to a target speed; subsequently, a load reduction is carried out on a positive-locking shift element of the range group (11) designed for executing the upshift, and the same is subsequently engaged to bring the range group (11) into neutral; subsequently, the input shaft (6) is synchronized to a first target speed, and subsequently the positive-locking shift element of the range group (11) to be engaged for executing the upshift is engaged; overlapping or subsequently, the main transmission (9) is brought into neutral.the input shaft (6) is synchronized to a second target speed and a positive-locking switching element of the main gearbox (9) for the execution of the upshift is engaged. ZF Friedrichshafen AG File 305279 Friedrichshafen 2024-10-30 2. Method according to claim 1, characterized in that when the motor vehicle is decelerated, the speed of the internal combustion engine (1) is reduced as a target speed to a minimum speed which corresponds to the idle speed of the internal combustion engine increased by a predetermined offset and multiplied by the gear step of the upshift to be performed, or to a speed dependent thereon which is greater than the minimum speed by an offset or a factor.

3. Method according to claim 1 or 2, characterized in that by synchronizing the input shaft (6) of the group transmission (2) to the first target speed, the positive-locking switching element of the range group (11) to be inserted for carrying out the upshift is synchronized.

4. Method according to claim 1, 2 or 3, characterized in that the synchronization of the input shaft (6) of the range transmission (2) to the first target speed is effected via friction losses of the range transmission (2) and / or the internal combustion engine (1), such that initially the disconnect clutch (5) is held closed, and then, when the input shaft (6) of the range transmission (2) reaches the first target speed before the internal combustion engine (1) reaches its idle speed, the positive-locking switching element of the range group (11) to be engaged for upshifting is actuated, and that, on the other hand, when the internal combustion engine (1) reaches its idle speed before the input shaft (6) of the range transmission (2) reaches the first target speed, the disconnect clutch (5) is opened before the internal combustion engine (1) reaches its idle speed, and then,when the input shaft (6) of the group transmission (2) subsequently reaches the first target speed, the positive-locking switching element of the range group (11) to be engaged for the execution of the upshift is actuated, and after the positive-locking switching element of the range group (11) to be engaged for the execution of the upshift, the disconnecting clutch (5) is closed again. ZF Friedrichshafen AG File 305279 Friedrichshafen 2024-10-30 5. Method according to one of claims 1 to 4, characterized in that by synchronizing the input shaft (6) of the group transmission (2) to the second target speed, the positive-locking switching element of the main transmission (9) to be inserted for carrying out the upshift is synchronized.

6. Method according to one of claims 1 to 5, characterized in that the input shaft (6) of the group transmission (2) is synchronized to the second target speed of the internal combustion engine (1) by accelerating the input shaft (5) of the group transmission (2) to the second target speed via the internal combustion engine (1).

7. Method according to one of claims 1 to 6, characterized in that, when a splitter group (10) upstream of the main gearbox (9) is also involved in the execution of the upshift, a positive-locking switching element to be designed for the execution of the upshift is designed and a positive-locking switching element to be inserted for the execution of the upshift is inserted in the splitter group (10) after the main gearbox (9) has been moved into neutral and before the input shaft (6) has been synchronized to the second target speed.

8. Method according to one of claims 1 to 7, characterized in that the upshifting is then carried out when, after a request for upshifting has been made based on a current and / or future driving situation, in particular a driving resistance and / or a road gradient, it is recognized that the upshifting can be carried out without switching element synchronization by the electric machine (4).

9. Control unit for operating a drive train of a motor vehicle, wherein the drive train comprises as a first drive unit an internal combustion engine (1), as a second drive unit an electric machine (4), and an automated group transmission (2) connected between the drive units and an output (3), wherein the internal combustion engine (1) is coupled to an input shaft (6) of the group transmission (2) via a switchable disconnect clutch (5), ZF Friedrichshafen AG File 305279 Friedrichshafen 2024-10-30 wherein the electric machine (4) is also coupled to the input shaft (6) of the group transmission (2), wherein the group transmission (2) has several sub-transmissions, namely at least one main transmission (9) and a drive-technically downstream range group (11) of the main transmission (9), characterized in that the control unit is configured for automatic, control-side execution of the method according to one of claims 1 to 8.

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