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 accelerated 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) is synchronized to a first target rotational speed, and 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 is synchronized to a second target rotational speed via the internal combustion engine (1), and a shifting element of the main transmission to be engaged in order to carry out the upshift is engaged.

Description

[0001] ZF Friedrichshafen AG File 305278 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 305278 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 motor vehicle is driving with the disconnect clutch engaged, and an upshift is to be performed in the range transmission, at least with the involvement of the range group and the main transmission, and the electric machine cannot be used for synchronizing the shifting element, the following steps are carried out according to the invention to perform the upshift:

[0012] The vehicle is accelerated in such a way that the internal combustion engine's speed is brought up to a target speed. In doing so, the engine speed is increased. ZF Friedrichshafen AG File 305278 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] The input shaft is then synchronized to a first target speed, and subsequently the positive-locking shift element of the range group, required for upshifting, is engaged. To synchronize the input shaft of the range gearbox to the first target speed, the engine speed is reduced.

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

[0016] The invention proposes a method that enables reliable upshifting in a range gearbox of a hybrid drive arrangement that lacks a gearbox brake, specifically when the electric motor cannot be used for synchronizing the shift elements. In the method according to the invention, the combustion engine is used, as far as possible, to synchronize the shift elements in an upshift involving both the main gearbox and the range gearbox downstream of the main gearbox.

[0017] Preferably, when accelerating the vehicle, the internal combustion engine's speed is increased to a target speed equal to the maximum permissible operating speed of the internal combustion engine under load, or to a speed dependent on this, which is lower than the maximum permissible operating speed of the internal combustion engine by an offset or a factor. This is preferred to ensure the highest possible connection speed for a relatively long upshift with large gear changes. ZF Friedrichshafen AG File 305278 Friedrichshafen 2024-10-30

[0018] Preferably, if the first target speed is greater than the idle speed of the internal combustion engine, the input shaft of the range transmission is synchronized to the first target speed via the internal combustion engine, and the positive-locking shift element of the range group, which is to be engaged to execute the upshift, is activated for engagement upon reaching the first target speed. In this case, the disconnect clutch can remain closed.Preferably, when the first target speed is lower than the idle speed of the internal combustion engine, the input shaft of the range gearbox is first guided via the internal combustion engine towards the first target speed. The disconnect clutch is then opened at an internal combustion engine speed higher than its idle speed, and the input shaft of the range gearbox is subsequently synchronized to the first target speed via friction losses within the range gearbox. The positive-locking shift element of the range group, required for upshifting, is activated either upon reaching the first target speed or before. In this case, opening the disconnect clutch prevents the idle speed governor from activating and increasing the internal combustion engine speed above idle.This is advantageous for comfort reasons and for synchronizing the input shaft of the range gearbox. To synchronize the input shaft of the range gearbox to the first target speed, the speed of the internal combustion engine is reduced in both cases with the disconnect clutch engaged, preferably using an engine braking device of the internal combustion engine, which can be designed, for example, as a decompression brake, primary retarder, or the like.

[0019] Preferably, when a splitter group upstream of the main transmission is involved in the upshift operation, 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 of the range transmission has been synchronized to the second target speed. This allows the splitter group to be integrated into the upshift operation even when the electric motor cannot be used for synchronizing the switching element, should this be necessary. ZF Friedrichshafen AG File 305278 Friedrichshafen 2024-10-30

[0020] Preferably, upshifting is performed when, after a request for upshifting has been received, it is determined, based on a current and / or future driving situation, in particular driving resistance and / or road gradient, that the upshifting can be performed by the electric motor without synchronization of the shifting element. Upshifts that cannot be performed without synchronization of the shifting element by the electric motor are prevented and not carried out. This is also advantageous for safety reasons, in particular to prevent the vehicle from breaking down.

[0021] 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:

[0022] Fig. 1 shows an exemplary scheme of a motor vehicle powertrain, namely a hybrid drive arrangement with a group transmission;

[0023] Fig. 2 is a signal flow diagram to illustrate the invention.

[0024] The invention relates to a method for operating a powertrain of a motor vehicle with a hybrid drive and an automated group transmission, as well as a control device for carrying out the method.

[0025] 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.

[0026] 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. ZF Friedrichshafen AG File 305278 Friedrichshafen 2024-10-30

[0027] In the illustrated embodiment, the electric machine 4 is permanently coupled to the input shaft 6 of the group gearbox 2, specifically via a planetary gear 30 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 group gearbox 2.

[0028] The output 3 is coupled to an output shaft 8 of the group gearbox 2.

[0029] 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.

[0030] 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. The associated fixed gears are arranged non-rotatably on the countershafts 21 and 22. The two switching elements 15, 16 or C, D and the two switching elements 18, 19 orE and F each form a switching package 17 and 20 respectively.

[0031] The split group 10 of the transmission 2, which is upstream of the main transmission 9, is designed in two stages in the illustrated embodiment and is also of reduction gear construction, with the two transmission stages K1 and K2 of the split group 10 forming two switchable input constants of the main transmission 9. The two transmission stages K1 and K2 have a smaller transmission ratio difference. The split group 10 of the transmission 2 is optional and can also be omitted. ZF Friedrichshafen AG File 305278 Friedrichshafen 2024-10-30

[0032] The loose gear of the first transmission stage K1 is rotatably mounted on the input shaft 6. The loose gear of the second transmission stage K2 is rotatably mounted on the main shaft. The fixed gears of both transmission stages K1 and K2 of the splitter assembly 10 are each rotationally fixed to the input-side extended countershafts 21 and 22 of the main gearbox 9. Synchronized switching elements 12 and 13, so-called synchronous switching elements, of the splitter assembly 10 are combined into a common switching unit 14. In Fig. 1, switching element 12 is designated as switching element A and switching element 13 as switching element B. The switching elements 12 and 13 are designed as positive-locking claw switching elements.

[0033] The range group 11 of the group gearbox 2, which is downstream of the main gearbox 9, is also designed as a two-stage gearbox, but as a planetary gearbox 24.

[0034] The sun gear 25 is non-rotatably connected to the output-side extended main shaft of the main gearbox 9. 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 slow-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.

[0035] In Fig. 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.

[0036] In Fig. 1, an optional oil pump 31 engages the countershaft 22 and can be driven from the countershaft 22.

[0037] 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. ZF Friedrichshafen AG File 305278 Friedrichshafen 2024-10-30

[0038] The present invention relates to a method by which it is possible to perform a shift, namely upshifting, at least with the involvement of the section group 11 and the main transmission 9, in a group transmission 2 which is part of a hybrid powertrain configuration of a motor vehicle, and in which, due to the omission of a transmission brake, the electric machine 4 is used to synchronize shifting elements, even if, for example, the electric machine 4 cannot be used for shifting element synchronization due to a fault or failure of a high-voltage system.

[0039] Referring to the group transmission 2 of Fig. 1, it is assumed that in the initial state for the method according to the invention, the motor vehicle is driving with the disconnect clutch 5 closed, either fully closed or partially closed, and a relatively low gear is engaged in the group transmission 2, in which the shifting element 29 or the shifting element H of the range group 11 is engaged, and that subsequently, with the involvement of the range group 11 and the main transmission 9, an upshift to a higher gear is to be carried out, for which it is then necessary in the range group 11 to disengage the shifting element 29 or the shifting element H and to insert the shifting element 28 or the shifting element G, and furthermore, in the main transmission 9, one of the positive-locking shifting elements 15, 16, 18, 19 must be disengaged and another of them inserted.The execution of such an upshift can be requested, for example, by the driver by a corresponding operation of the accelerator pedal or gas pedal.

[0040] In this context, it may be provided that, for example, if an upshift is requested as a result of driver input of the accelerator pedal, a check is first performed, either at or after the upshift request, to determine whether the upshift can be executed by the electric motor 4 without shift element synchronization. This check can be based on a current and / or future driving situation, in particular driving resistance and / or road gradient. ZF Friedrichshafen AG File 305278 Friedrichshafen 2024-10-30

[0041] Only if it is determined that, in particular based on the current driving resistance and / or the current and / or future road gradient, the upshift can be carried out by the electric machine 4 even without switching element synchronization when an upshift request exists, will it actually be carried out.

[0042] 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.

[0043] To execute the upshift in the transmission 2 without shift element synchronization by the electric motor 4, the vehicle is first accelerated such that the internal combustion engine's speed is brought up to a target speed. During acceleration, the internal combustion engine's speed is preferably increased to a maximum permissible operating speed for the engine, or alternatively to a speed dependent on this, which is lower than the maximum permissible operating speed for the engine by an offset or a factor. This ensures, on the one hand, the highest possible connection speed when upshifting with large gear changes, and on the other hand, allows a significant portion of the differential speed to be reduced during the subsequent shifting process until the engine's idle speed is reached.

[0044] Following acceleration of the motor vehicle, the load is reduced at the positive-locking switching element of range group 11, i.e., at switching element 29 or switching element H in Fig. 1, which is designed to execute the upshift, in particular by reducing torque at the internal combustion engine 1 while preferably maintaining a constant internal combustion engine speed. ZF Friedrichshafen AG File 305278 Friedrichshafen 2024-10-30

[0045] Following the load reduction at the positive-locking switching element of area group 11, which is designed for upshifting (i.e., following the load reduction at switching element 29 or switching element H of area group 11 in Fig. 1), this switching element of area group 11 is designed to thereby bring area group 11 into neutral. The drive train is then open.

[0046] Subsequently, the input shaft 6 of the group transmission 2 is synchronized to a first target speed in order to synchronize the positive-locking switching element of range group 1 1 to be engaged for the execution of the upshift, namely the switching element 28 or G in Fig. 1. To synchronize the input shaft 6 of the group transmission 2 to the first target speed, the speed of the input shaft 6 of the group transmission 2 is reduced and for this purpose the internal combustion engine 1 is preferably used as far as possible, in particular an engine braking device of the internal combustion engine 1 designed as a decompression brake or primary retarder.

[0047] Then, when the first target speed is greater than the idle speed of the internal combustion engine 1, the input shaft 6 of the range gearbox 2 is synchronized to the first target speed via the internal combustion engine 1, and the disconnect clutch 5 can remain closed. The positive-locking shift element of range group 11, i.e., shift element 28 or shift element G of range group 11 in Fig. 1, which is to be engaged to execute the upshift, is then activated for engagement and is therefore engaged when the speed of the input shaft 6 of the range gearbox 2 has reached the first target speed.

[0048] However, if the first target speed for the input shaft 6 of the transmission 2 is lower than the idle speed of the internal combustion engine 1, the input shaft 6 of the transmission 2 is initially guided via the internal combustion engine 1 towards the first target speed. During this process, the disconnect clutch 5 is opened at an internal combustion engine 1 speed that is a defined offset higher than its idle speed. This disconnects the internal combustion engine 1 from the transmission 2 and prevents the internal combustion engine 1 speed from dropping below idle speed, thus preventing the idle speed governor of the internal combustion engine 1 from engaging. ZF Friedrichshafen AG File 305278 Friedrichshafen 2024-10-30

[0049] With the disconnect clutch 5 open, the input shaft 6 of the transmission 2 is then synchronized to the first target speed via friction losses of the transmission 2. The positive-locking switching element of range group 1, which is used to perform the upshift (in Fig. 1, the switching element 28 or switching element G), is activated either upon reaching the first target speed or alternatively before reaching the first target speed. If the activation of the switching element 28, which is to close in range group 11, occurs before the first target speed is reached at the input shaft 6 of the transmission, the switching element 28 or switching element G is subjected to a ratcheting action during activation. It may be possible to activate the closing of the switching element 28, which is to close in range group 11, when a predetermined differential speed of, for example, less than 300 rpm is present at the same point.

[0050] Simultaneously with the insertion of the positive-locking shift element of range group 11 for upshifting, or following the insertion of the positive-locking shift element of range group 11 for upshifting, the main transmission 9 is shifted into neutral by engaging a positive-locking shift element in the main transmission 9. Subsequently, the input shaft 6 of the range transmission 2 is synchronized via the internal combustion engine 1 to a second target speed in order to synchronize the positive-locking shift element of the main transmission 9 for upshifting and subsequently engage it. During the synchronization of the input shaft 6 of the range transmission 2 to the second target speed, the speed of the internal combustion engine 1 is increased.

[0051] If the splitter group upstream of the main transmission 9 is also involved in the upshift operation, the gear is changed in splitter group 10 after the main transmission 9 has been shifted into neutral and before the input shaft 6 of the range transmission 2 has been synchronized to the second target speed. This is achieved by disengaging one of the shift elements 12, 13 of splitter group 10 and engaging the other. This occurs when the main transmission 9 is in neutral. ZF Friedrichshafen AG File 305278 Friedrichshafen 2024-10-30

[0052] The inventive method is described below with reference to Fig. 2 for an exemplary upshift from gear 6 to gear 7.

[0053] In gear 6, the switching element 13 or the switching element B is engaged in the split group 10 of the group transmission 2, the switching element 15 or the switching element C is engaged in the main transmission 9 of the group transmission 2, and the switching element 29 or the switching element H is engaged in the range group 11 of the group transmission 2.

[0054] In gear 7, the switching element 12 or the switching element A is engaged in the split group 10 of the group transmission 2, the switching element 18 or the switching element E is engaged in the main transmission 9 of the group transmission 2, and the switching element 28 or the switching element G is engaged in the range group 11 of the group transmission 2.

[0055] In Fig. 2, in block 32, the motor vehicle with the drivetrain of Fig. 1 is traveling in gear 6 with shift element B, shift element C, and shift element H engaged and with the disconnect clutch 5 closed. Starting from such a state, in block 33, for example, depending on a driver-side accelerator pedal actuation, an upshift request from gear 6 to gear 7 is detected, whereby shift elements A, E, and G are engaged in gear 7.

[0056] In order to carry out this gear change without the involvement of the electric machine 4 for synchronizing the switching element, the drive train is preconditioned in a block 33 by accelerating the motor vehicle in such a way that the rotational speed of the internal combustion engine is brought to a target speed.

[0057] Preferably, when the motor vehicle accelerates in a block 33, the speed of the internal combustion engine 1 is increased as a target speed to the maximum permissible traction operating speed of the internal combustion engine 1 or to a speed dependent thereon, which is smaller than the maximum permissible traction operating speed of the internal combustion engine 1 by an offset or a factor. ZF Friedrichshafen AG File 305278 Friedrichshafen 2024-10-30

[0058] In the following, in block 34, the area group 11 is converted to neutral by placing the switching element H in Fig. 1.

[0059] Subsequently, in a block 35, the input shaft 6 of the group transmission 2 is guided via the internal combustion engine 1, namely via an engine braking device thereof, in the direction of the first target speed, and in the embodiment of Fig. 2 in the direction of a first target speed which is less than the idle speed of the internal combustion engine 1, so that in a block 36 the disconnect clutch 5 of the drive train is opened, at a speed which is greater than the idle speed of the internal combustion engine 1 by a defined offset.

[0060] With the disconnect clutch 5 open, the input shaft 6 of the group gearbox 2 is synchronized either according to block 37 exclusively by drag losses of the gearbox or according to block 38 additionally by a ratcheting of the switching element G to be inserted in the group gearbox 11 in order to insert the switching element G in a block 39 in the group gearbox 11.

[0061] In Fig. 2, the main gearbox 9 is subsequently shifted into neutral in block 40 by disengaging the shifting element C in the main gearbox 9. Then, in block 41, the previously opened disconnect clutch 5 is closed again.

[0062] Subsequently, in block 42 of Fig. 2, a switching operation is performed in the split group 10 by disengaging the switching element B and engaging the switching element A. This is done, as shown in Fig. 2, with the main gearbox 9 in neutral and the disconnect clutch 5 closed.

[0063] After switching the split group 10, the speed of the input shaft 6 of the group transmission 2 is synchronized to the second target speed in block 43 in order to synchronize the shift element E of the main transmission 9. After successful synchronization, the shift element E of the main transmission 9 is engaged in block 44. In block 45, the vehicle then travels in gear 7 with shift elements A, E, and G engaged. ZF Friedrichshafen AG File 305278 Friedrichshafen 2024-10-30

[0064] As already explained above, the inventive method was described with reference to Fig. 2 for the case in which the first target speed for the input shaft 6 of the group transmission 2 is less than the idle speed of the internal combustion engine 1. If, on the other hand, the first target speed for the input shaft 6 of the group transmission 2 is greater than the idle speed of the internal combustion engine 1, blocks 36, 37, 38 and 41 can be omitted, since in this case the disconnect clutch 5 does not need to be opened.

[0065] Furthermore, with reference to Fig. 2, the procedure was described for a case in which the splitter group 10, which is upstream of the main transmission 9 on the drive side, also needs to be switched. This is the case with the group transmission 2 of Fig. 1 for the gear change from gear 6 to gear 7. If, however, an upshift from gear 5, in which the switching elements A, C, and H are closed, to gear 7, in which the switching elements A, E, and H are closed, is to be carried out for the group transmission 2, then the switching of the splitter group 10 and, in Fig. 2, block 42, is omitted. The switching of the splitter group 10 is also omitted if an upshift from gear 3, in which the switching elements A, D, and H are closed, to gear 7, in which the switching elements A, E, and G are closed, is to be carried out for the group transmission 2 of Fig. 1.

[0066] The invention further relates to a control unit configured to automatically execute the above-described inventive method on the control side. The control unit has hardware and software means for this purpose.

[0067] Hardware components include data interfaces for exchanging data with the assemblies involved in carrying out the method according to the invention, for example, for controlling the combustion engine 1 and the switching elements involved in executing the upshift. Hardware components also include a processor for data processing and a memory for data storage. Software components include program modules implemented in the control unit for carrying out the method according to the invention. ZF Friedrichshafen AG File 305278 Friedrichshafen 2024-10-30

[0068] Reference mark

[0069] 1 Internal combustion engine

[0070] 2-group gearbox

[0071] 3 Drive

[0072] 4 electric machine

[0073] 5 Disconnect coupling

[0074] 6 Input wave

[0075] 7 Housing part

[0076] 8 Output wave

[0077] 9 Main gearboxes

[0078] 10 Split group

[0079] 11 Area Group

[0080] 12 Synchronous switching element

[0081] 13 Synchronous switching element

[0082] 14 shift package

[0083] 15 switching element

[0084] 16 switching element

[0085] 17 shift package

[0086] 18 switching element

[0087] 19 Switching element

[0088] 20 shift package

[0089] 21 Countershaft

[0090] 22 Countershaft

[0091] 23 Shift package

[0092] 24 planetary gears

[0093] 25 sun wheel

[0094] 26 Ring gear

[0095] 27 planetary carriers

[0096] 28 switching element

[0097] 29 Switching element

[0098] 30 planetary gears

[0099] 31 Oil pump

[0100] 32 Block ZF Friedrichshafen AG File 305278 Friedrichshafen 2024-10-30

[0101] Block 33

[0102] Block 34

[0103] 35 Block

[0104] 36 Block

[0105] Block 37

[0106] 38 Block

[0107] Block 39

[0108] 40 blocks

[0109] Block 41

[0110] 42 Block

[0111] Block 43

[0112] 44 Block

[0113] 45 Block

Claims

ZF Friedrichshafen AG File 305278 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 accelerated so 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 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 via the internal combustion engine (1) and a shift element of the main transmission (9) to be engaged for the execution of the upshift is engaged. ZF Friedrichshafen AG File 305278 Friedrichshafen 2024-10-30 2. Method according to claim 1, characterized in that when accelerating the motor vehicle, the speed of the internal combustion engine (1) is increased as a target speed to a maximum permissible traction operating speed of the internal combustion engine (1) or to a speed dependent thereon, which is smaller than the maximum permissible traction operating speed of the internal combustion engine (1) 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 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.

5. Method according to one of claims 1 to 4, characterized in that when the first target speed is greater than an idle speed of the internal combustion engine (1 ), the input shaft (6) of the group transmission (2) is synchronized to the first target speed via the internal combustion engine (1 ) and the positive-locking switching element of the range group to be engaged for the execution of the upshift is actuated for engagement upon reaching the first target speed.

6. Method according to one of claims 1 to 5, characterized in that when the first target speed is less than the idle speed of the internal combustion engine (1), the input shaft (6) of the range transmission (2) is first guided via the internal combustion engine (1) in the direction of the first target speed, the disconnect clutch (5) is opened at a speed of the internal combustion engine (1) that is greater than its idle speed, and the input shaft (6) of the range transmission (2) is subsequently synchronized to the first target speed via friction losses of the range transmission (2), wherein the positive-locking switching element of the range group (11) to be engaged for the execution of the upshift is actuated either upon reaching the first target speed or before. ZF Friedrichshafen AG File 305278 Friedrichshafen 2024-10-30 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 designed in the splitter group (10) after the main gearbox (9) has been moved into neutral and before the input shaft (5) of the group gearbox (2) 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), wherein the electric machine (4) is also coupled to the input shaft (6) of the group transmission (2), and wherein the group 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) in terms of drive technology, characterized in that the control unit is configured for the automatic, control-side execution of the method according to one of claims 1 to 8.

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