Method for operating a transmission device

Abstract

Method for operating a transmission device (1), in particular a 9-speed transmission, which can be transferred into different operating states via the actuation of shifting elements (A to F), wherein at least one of the shifting elements (A, F) is designed as a positive shifting element which is to be transferred into a closed operating state to represent at least one defined operating state of the transmission device (1), during which a power flow exists between a transmission input shaft (2) and a transmission output shaft (3), wherein, when there is a request to close the positive shifting element (A, F), a rotational speed (nt) of the transmission input shaft (2) or a rotational speed equivalent thereto is guided in the direction of a synchronous rotational speed (nt("4")), which is established in the closed operating state of the positive shifting element (F) at least as a function of the rotational speed of the transmission output shaft (3),wherein the engagement process of the positive-locking shift element (F) in the open operating state is aborted if the profile of the rotational speed (nt) of the transmission input shaft (2) or the rotational speed equivalent thereto crosses a predefined rotational speed threshold (ntS3) after reaching the synchronous rotational speed (nt("4")) with the positive-locking shift element (F) actuated in the closing direction, characterized in that the engagement process of the positive-locking shift element (A, F) is aborted if the profile of the rotational speed (nt) of the transmission input shaft (2) or the rotational speed equivalent thereto crosses an additional predefined rotational speed threshold (ntS1) before reaching the synchronous rotational speed (nt("4")), without actuation of the positive-locking shift element (A, F) in the closing direction being requested.

Description

[0001] The invention relates to a method for operating a transmission device according to the type defined in more detail in the preamble of patent claim 1.

[0002] A transmission device designed as an 8-speed multi-stage transmission with frictional shifting elements, such as multi-disk clutches and multi-disk brakes, is known from DE 10 2005 002 337 A1. When a shift request for a gear ratio change is present in the transmission device, at least one frictional shifting element, which is connected to the power flow of the transmission device to display the actual gear ratio currently engaged in the transmission device, is to be disconnected from the power flow of the transmission device, while at least one further frictional shifting element, which is disconnected from the power flow of the transmission device while the actual gear ratio currently engaged in the transmission device is being displayed, is to be connected to the power flow of the transmission device to display the requested target gear ratio.

[0003] As the switching time increases, the torque transmitted via the frictional switching element connected to the power flow to represent the current actual gear ratio of the transmission device is transmitted more or less by the frictional switching element to be connected to the power flow of the transmission device to represent the requested target gear ratios, while the torque that can be transmitted via the switching element to be disconnected decreases.

[0004] Unfortunately, friction-locked shift elements in the open operating state cause drag torques, which adversely affect the overall efficiency of an automatic transmission.

[0005] For this reason, transmission devices, such as those known from DE 10 2008 000 429 A1, are increasingly being designed with positive-locking switching elements in addition to frictional switching elements, in the area of which no drag torques occur that impair the overall efficiency of a transmission device.

[0006] However, it should be noted that positive-locking shift elements can only be switched from an open operating state, in which no torque can be transmitted via the positive-locking shift elements, to their closed operating state, in which the entire applied torque can be transmitted via the positive-locking shift elements, near their synchronization point. In addition, positive-locking shift elements connected to the power flow of a transmission device with low switching forces can only be switched off from the power flow near their load-free operating state.

[0007] When a request is made to close a positive shifting element by applying a corresponding closing force to the positive shifting element, the shift command is issued by an electronic transmission control unit or software with a certain time lead before reaching the synchronization point of the positive shifting element, which the positive shifting element has when the target gear ratio is engaged. This is intended to ensure that the actual engagement process or meshing of the positive shifting element takes place within a predefined differential speed window between the two shifting element halves, within which the positive shifting element can be engaged with a high degree of probability.In addition, the time lead factor should take into account system-inherent delays caused, for example, by signal propagation times, hydraulic delays, and / or the distance to be covered to close the connection. The time lead factor to be provided depends to a significant extent on the operating temperature of the transmission device or the temperature of the transmission oil, particularly in the case of hydraulically actuated positive shifting elements of transmission devices, such as automatic transmissions.

[0008] The time lead required for triggering the closing process of the positive-locking shift element can be determined empirically, for example. Furthermore, it is also possible to determine the time lead for the engagement point of the positive-locking shift element depending on the currently existing gradient of the speed of a transmission input shaft or an equivalent speed, such as a turbine speed or the like, before reaching the synchronization point of the positive-locking shift element, and to specify the control of the positive-locking shift element accordingly.

[0009] To calculate gradients of speed curves, multiple speed values are usually used due to signal noise to avoid incorrect control. However, this approach leads to significant speed changes, for example, not being detectable in a timely manner via gradients calculated in this way, since the complex calculation methods used to avoid errors delay the visibility of changes.

[0010] If the closing process of a positive-locking switching element is not initiated in time before the synchronization point of the positive-locking switching element is reached, an attempt is made to close the positive-locking switching element at an excessively high differential speed between the two switching element halves. The positive-locking switching element cannot then be transferred to its closed operating state, and there is also the possibility of damage occurring in the area of the positive-locking switching element if the switching element halves that are to be brought into positive engagement only contact each other in the area of their facing end surfaces, and any resulting abrasion impairs the functioning of the positive-locking switching element.

[0011] A comparable transmission device with at least one positive switching element is also known from DE 10 2005 054 767 A1.

[0012] The present invention is therefore based on the object of providing a method for operating a transmission device by means of which damage in the area of positive switching elements due to closing processes that are not triggered in a timely manner can be avoided in a simple manner.

[0013] According to the invention, this object is achieved by a method having the features of patent claim 1.

[0014] In the method according to the invention for operating a transmission device, in particular a 9-speed transmission, which can be transferred into different operating states via the actuation of shifting elements, wherein at least one of the shifting elements is designed as a positive shifting element which is to be transferred into a closed operating state to represent at least one defined operating state of the transmission device, during which a power flow between a transmission input shaft and a transmission output shaft is present, when there is a request to close the positive shifting element, a speed of the transmission input shaft or a speed equivalent thereto is guided in the direction of a synchronous speed which is set in the closed operating state of the positive shifting element at least as a function of the speed of the transmission output shaft.

[0015] In order to avoid damage in the area of a positive-locking switching element to be closed, the engagement process of the positive-locking switching element in the open operating state is aborted if the speed profile of the transmission input speed or the speed equivalent thereto crosses a predefined speed threshold after reaching the synchronous speed when the positive-locking switching element is already actuated in the closing direction, whereby the engagement process of the positive-locking switching element is aborted if the speed profile of the transmission input shaft or the speed equivalent thereto crosses an additional predefined speed threshold before reaching the synchronous speed, without actuation of the positive-locking switching element in the closing direction being requested.

[0016] It is known that a requested closing process of a positive-locking switching element cannot be realized to the required extent outside the differential speed window between the switching element halves that is favorable for meshing, and irreversible damage may occur in the area of the positive-locking switching element during an unsuccessful closing process.

[0017] If the speed of the transmission input speed or the equivalent speed reaches the predefined speed threshold, it is assumed that the positive switching element cannot be transferred to its closed operating state to the desired extent, which is why the engagement process is then aborted in order to easily avoid an incorrect switching process.

[0018] In an advantageous variant of the method according to the invention, a timer is started when the speed profile of the transmission input shaft or the speed equivalent thereto, after reaching the synchronous speed with the positive shifting element actuated in the closing direction, crosses another predefined speed threshold before the predefined speed threshold, wherein the engagement process of the positive shifting element in the open operating state is aborted when the value of the timer reaches a predefined value. This procedure, in turn, ensures that with correspondingly low gradients of the speed profile of the transmission input shaft ora differential speed between the switching element halves of the positive-locking switching element to be closed, undesirably long switching processes are terminated without the positive-locking switching element being successfully closed before the additional predefined speed threshold representing a termination criterion is reached and, on the one hand, damage in the area of the positive-locking switching element is avoided and, on the other hand, an undefined intermediate operating state of a transmission device only exists for a limited period of time.

[0019] In a further advantageous variant of the method according to the invention, the engagement process of the positive shifting element is aborted if the speed profile of the transmission input shaft or the speed equivalent thereto crosses an additional predefined speed threshold before reaching the synchronous speed, without actuation of the positive shifting element in the closing direction being requested. Damage in the area of a positive shifting element to be engaged is thus easily avoided, since the engagement process of the positive shifting element is aborted if the transmission control unit or software has not yet initiated the closing of the positive connection up to a defined differential speed point in the area of the positive shifting element before reaching the synchronous operating state of the positive shifting element.

[0020] In a further advantageous variant of the method according to the invention, a point in time is determined before the synchronous speed is reached, from which point an actuation of the positive shifting element acting in the closing direction of the positive shifting element is to be started. The engagement process of the positive shifting element is aborted if the speed profile of the transmission input speed or the speed equivalent thereto crosses the additional predefined speed threshold at a point in time that lies before the determined start of actuation of the positive shifting element in the closing direction. This procedure ensures that engagement processes or closing processes of a positive shifting element, which are obviously started too late depending on the operating state and therefore cannot be completed to the desired extent with low component loads, are aborted in a timely manner.

[0021] If the positive-locking switching element is actuated in the closing direction when the speed of the transmission input shaft or the speed equivalent thereto crosses an additional predefined speed threshold which reaches the speed of the transmission input shaft or the speed equivalent thereto before the additional predefined speed threshold, a so-called forced activation of the previously not actuated positive-locking switching element is triggered in order to activate the positive-locking switching element to the requested extent and in turn to avoid too late actuation of the switching element and resulting damage to the positive-locking switching element.

[0022] After the engagement process of the positive shifting element is aborted, the transmission device is transferred to a safe operating state in which both the transmission input shaft and the transmission output shaft are rotatable. This easily prevents safety-critical operating states, such as a blocked output of a vehicle equipped with the transmission device operated according to the invention.

[0023] In a preferred variant of the method according to the invention, the safe operating state of the transmission device corresponds to a neutral operating state in which the power flow between the transmission input shaft and the transmission output shaft is interrupted, wherein for this purpose preferably all switching elements of the transmission device are transferred to their open operating state.

[0024] Alternatively, the safe operating state corresponds to the operating state of the transmission device before the request to close the positive switching element.

[0025] If the speed threshold, the further speed threshold, the additional speed threshold and / or the additional further speed threshold vary depending on an operating temperature of the transmission device, damage in the area of a positive switching element can be avoided with little effort over the entire operating range of a transmission device.

[0026] Additionally or alternatively, it is possible to vary the speed threshold, the further speed threshold, the additional speed threshold and / or the additional further speed threshold depending on a gradient of a course of the difference between the currently existing speed of the transmission input shaft and the synchronous speed of the transmission input shaft or the speed equivalent thereto in order to avoid damage in the area of a positive switching element to be closed, adapted to the respective existing operating state course.

[0027] Further advantages and advantageous developments of the invention emerge from the patent claims and the exemplary embodiments described in principle with reference to the drawing.

[0028] It shows: Fig. 1 a wheel set diagram of a transmission device; Fig. 2 a tabular circuit logic of the Fig. 1 shown gear device; Fig. 3 a comparison of several curves of different operating state parameters of the transmission device according to Fig. 1, which occur during a properly executed connection process and during a timely termination of a connection process of a positive switching element that has not yet been actuated; and Fig. 4 a Fig. 3 corresponding representation of several curves of different operating state parameters of the transmission device according to Fig. 1 during a switching process of a positive-locking switching element already actuated in the closing direction when a faulty closing process is detected.

[0029] Fig. Figure 1 shows a gear diagram of a transmission device 1 or a 9-speed transmission, which is generally known from DE 10 2008 000 429 A1. The transmission device 1 comprises a drive shaft 2 and an output shaft 3, which, when mounted in a vehicle, is connected to an output of the vehicle, while the drive shaft 2 is operatively connected to a drive engine.

[0030] Furthermore, the transmission device 1 comprises four planetary gear sets P1 to P4, wherein the first and second planetary gear sets P1, P2, which are preferably designed as negative planetary gear sets, form a switchable primary gear set, while the third and fourth planetary gear sets P3 and P4 represent the main gear set. In addition, the transmission device 1 comprises six shift elements A to F, of which shift elements C, D, and F are designed as brakes and shift elements A, B, and E are designed as clutches.

[0031] The switching elements A to F are connected according to the Fig. 2, a selective switching of nine forward gears “1” to “9” and one reverse gear “R” can be realized, wherein in order to establish a power flow in the transmission device 1, essentially three switching elements are to be led or held in a closed operating state at the same time.

[0032] The shifting elements A and F are designed here as positive-locking shifting elements without additional synchronization in order to reduce drag torques caused by open frictional shifting elements during operation of the transmission device 1, compared to transmission devices designed only with frictional shifting elements. Since positive-locking shifting elements can generally only be converted from an open operating state to a closed operating state within a very narrow differential speed band around the synchronous speed, the synchronization of a positive-locking shifting element to be engaged is realized without additional structural modifications by corresponding actuation of the shifting elements involved in the shifting.This applies to both traction and overrun shifts, whereby the positive shift elements can be designed as claw clutches, which are designed with or without additional synchronization.

[0033] The mode of operation of the method according to the invention is explained by the Fig. 3 and Fig. 4 shows the curves of several operating parameters of the transmission device 1 plotted against time t in accordance with Fig. 1. The method according to the invention can be used both for monitoring and actuating the positive shifting element F during a requested gear change starting from the fifth gear ratio “5” in the direction of the fourth gear ratio “4”, for the implementation of which the frictional shifting element B must be switched off and the positive shifting element F must be switched on, and for monitoring and actuating the positive shifting element A during a requested gear change starting from the eighth gear ratio “8” in the direction of the seventh gear ratio “7”, for the implementation of which the frictional shifting element C must be switched off and the positive shifting element A must be switched on.Furthermore, the method according to the invention can also be operated in a suitable manner during operating state sequences during which a frictional connection is established in the region of the transmission device 1 by closing the positive shift element A and / or F in the form of a so-called gear engagement, as may be the case, for example, when leaving a coasting mode of a vehicle equipped with the transmission device 1. In addition, the method according to the invention can also be used for operating state sequences during which a positive shift element is to be transferred from an open to a closed operating state in order to carry out a requested upshift.

[0034] Up to a time T1, the fifth gear ratio "5" or the eighth gear ratio "8" for forward travel is engaged in the transmission device 1. At time T1, a request is made for a gear ratio change starting from the currently engaged actual gear ratio "5" or "8" towards the fourth gear ratio "4" or the seventh gear ratio "7" for forward travel or the target gear ratio, whereby for this purpose the frictional shift element B or the shift element C must be opened and at the same time the positive shift element F or the shift element A must be transferred from its open operating state to its closed operating state.

[0035] At time T1, at which the frictional shift element B or the shift element C is still fully closed and the positive shift element F or the shift element A is in the fully open operating state and the fifth gear ratio “5” or the eighth gear ratio “8” is engaged, a speed nt of the transmission input shaft 2 corresponds to the synchronous speed nt(“5”) or nt(“8”), which is set in the transmission device 1 when the fifth gear ratio “5” or the eighth gear ratio “8” is engaged.

[0036] For the sake of clarity, the procedure according to the invention is described in more detail below essentially only for the positive shifting element F, wherein the presented sequence corresponds to the sequence provided for the actuation and monitoring of the positive shifting element A during a requested gear change from the eighth gear ratio “8” towards the seventh gear ratio “7”.

[0037] From a time T2 following time T1, at which the shift request is present starting from the actual gear ratio "5" in the direction of the target gear ratio "4", the transmission capacity of the frictionally engaged shifting element B is reduced by a corresponding reduction in the actuating pressure, whereby the speed nt of the transmission input shaft 2 increases in the direction of the synchronous speed nt("4"), which occurs when the fourth gear ratio "4" is engaged in the transmission device 1. At the same time, at time T2, which represents the start of the downshift starting from the fifth gear ratio "5" in the direction of the fourth gear ratio "4", the time before reaching the synchronous speed nt("4") is determined, from which an actuation of the positive shifting element F acting in the closing direction of the positive shifting element F is to be started.In addition, the difference between the speed nt of the transmission input shaft 2 and the synchronous speed nt(“4”) is constantly determined.

[0038] If the time T3 corresponds to the time determined depending on the operating state, from which the positive switching element F is to be subjected to the actuating force required for closing, at the time T3 a curve of the control current IF of the positive switching element F is abruptly recorded in the Fig. 3 is lifted in the manner idealized and the positive switching element F is actuated to the desired extent.

[0039] If a later time, for example time T4, is determined for the start of actuation of the positive switching element F, the procedure according to the invention described below takes effect.

[0040] The time T4 determined as the start of switching on simultaneously represents the time at which the control current IF is in the Fig. 3 is abruptly increased in the manner shown by the dashed curve of the control current IF. At time T4, the speed nt of the transmission input shaft 2 also coincidentally reaches the synchronous speed nt("4"). Irrespective of this, however, the engagement process of the positive switching element F, which has not yet been actuated in the closing direction by the transmission control unit of the transmission device 1, is aborted upon crossing a speed threshold ntS1, which is lower than the synchronous speed nt("4") and is crossed in the present case by the speed curve nt of the transmission input shaft 2 at a time T8.The reason for this is that when the actuation begins at values of the speed nt of the transmission input shaft 2 that are greater than the speed threshold ntS1, the positive switching element can no longer be guided into the closed state in the differential speed window required for engagement between the switching element halves of the positive switching element F that are to be brought into positive engagement with one another, and the speed threshold ntS1 represents a limit above which the start of actuation of the positive switching element F in the closing direction no longer leads to successful engagement.

[0041] Depending on the particular application, it is also possible for the positive shifting element F to be transferred to the closed operating state via a so-called forced engagement. For this purpose, a further speed threshold ntS2 must then be stored in the transmission control system. If this speed threshold ntS2 is exceeded by the speed nt of the transmission input shaft 2, which in this case is below the first speed threshold ntS1 and in this case is crossed by the curve of the speed nt of the transmission input shaft 2 at a time T9, the actuation of the positive shifting element F in the closing direction is initiated, even though the time T4 has not yet been reached. The second speed threshold ntS2 represents a speed value of the transmission input shaft 2 from which a initiated closing process can be carried out with a high probability without causing damage in the area of the positive shifting element F.

[0042] This in turn means that if the forced activation, which may be triggered by crossing the further speed threshold ntS2, fails to occur when the speed threshold ntS1 is reached, the actuation of the positive switching element F in the closing direction will no longer begin if it has not already started. The speed threshold ntS1 thus represents a safety threshold for the further speed threshold ntS2, in case this does not necessarily lead to the actuation of the positive switching element in the closing direction when exceeded, for example due to a fault.

[0043] In contrast, the Fig. 4 occur when the transmission device 1 shifts down from the fifth gear ratio “5” towards the fourth gear ratio “4” if the actuation of the switching element F was started in good time by the electrical transmission control unit and is already being actuated.

[0044] At time T1, a request is again made for the downshift from the fifth gear ratio “5” towards the fourth gear ratio “4” in the transmission device 1, whereby at time T2 the frictional shift element B is in the Fig.3 and its transmission capacity is reduced in order to guide the speed nt of the transmission input shaft 2 to the extent described above from the synchronous speed nt(“5”) towards the synchronous speed nt(“4”) of the target gear ratio “4”. At time T3, the transmission control unit actuates the positive shift element F in order to transfer it to the requested closed operating state. At a time T5, the speed nt of the transmission input shaft 2 corresponds to the synchronous speed nt(“4”) of the target gear ratio “4” to be engaged, whereby the positive shift element F is not yet in its closed operating state at time T5. In addition, during the started closing process of the positive shift element F orAfter the positive switching element F has begun to be actuated, a differential speed ndF between the two switching element halves of the positive switching element F that are to be connected to one another in a form-fitting manner is permanently determined and monitored.

[0045] The differential speed ndF reaches its maximum value between times T1 and T2. As the transmission capacity of the friction-locking switching element B decreases, the differential speed ndF decreases progressively and is essentially zero at time T5. Since the positive-locking switching element F is not yet closed at time T5 despite the actuation of the positive-locking switching element F having begun at time T3, the differential speed ndF increases toward positive values with increasing operating time t.

[0046] At a time T6, the speed nt of the transmission input shaft 2 crosses a speed threshold ntS4 or the differential speed ndF dependent thereon crosses a corresponding speed threshold ndFS4, and a timer is started. As the operating time t increases, the timer value is increased continuously or cyclically. If the timer reaches a predefined value before the positive-locking switching element is fully closed, the engagement process of the positive-locking switching element F is aborted, and the transmission device is transferred to a safe operating state, at which all switching elements A to F are preferably in the open operating state.

[0047] If the speed nt of the transmission input shaft 2 reaches a speed threshold ntS3 or the differential speed ndF reaches a speed threshold ndFS3 at a time T7 before the timer has the predefined value, the crossing of the speed nt of the transmission input shaft 2 of the third speed threshold ntS3 or the crossing of the differential speed ndF of the speed threshold ndFS3 leads to the termination of the engagement process of the positive shifting element F, since the method according to the invention or the monitoring function started by the request for the downshift then recognizes that the differential speed ndF in the area of the positive shifting element F has reached values that are too high for the requested closing process of the positive shifting element F to be carried out correctly.

[0048] This procedure generally makes it possible to detect complete non-engagement and also brief engagement followed by disengagement in the area of a positive-locking switching element, thus reliably preventing damage or increased wear in the area of a positive-locking switching element that is not closed to the required extent.

[0049] After the closing process of the positive switching element F has been aborted, it is possible to transfer the transmission device 1 both directly or indirectly, i.e. via an intermediate control, into an operating state in which a gear ratio is engaged in the transmission device 1, in the representation of which the positive switching element F is not involved. Furthermore, it is also possible for the transmission device 1 to be transferred into a non-positive operating state in which all switching elements A to F are open. In general, depending on the respective wheelset system, it must be ensured that positive switching elements can be transferred into an open operating state against all internally acting forces or moments if the safe operating state in which all switching elements should be in the open operating state is to be represented.

[0050] The speed threshold ntS1, the speed threshold ntS2, the speed threshold ntS3 and / or the speed threshold ntS4 can be varied depending on the application in dependence on the operating temperature of the transmission device 1 or the transmission oil, whereby viscosity-dependent variations with regard to the control of the positive switching element F can be represented to the desired extent.In addition, it is also possible to vary the speed thresholds ntS1 and / or ntS2 depending on a load applied to the transmission device and / or a gradient of the speed nt of the transmission input shaft 2 in order to carry out the actuation of the positive switching element F depending on the respective operating state curve or to abort it accordingly and to avoid permanently existing undefined operating states of the transmission device 1 as well as to prevent irreversible damage in the area of the positive switching element F due to a closing process that cannot be carried out depending on the operating state. Reference symbol 1 gear device 2 drive shaft 3 Output shaft “1” to “9” gear ratio for forward travel A to F switching element IF Control current of the positive switching element F ndF Differential speed of the positive switching element F ndFS3, ndFS4 predefined speed threshold nt nt(“4”), nt(“5”), speed of the transmission input shaft nt(“8”) Synchronous speed ntS1 to ntS4 predefined speed threshold “R” gear ratio for reverse t time T1 to T9 discrete time

Claims

[1] A method for operating a transmission device (1), in particular a 9-speed transmission, which can be transferred into different operating states via the actuation of shifting elements (A to F), wherein at least one of the shifting elements (A, F) is designed as a positive shifting element which is to be transferred into a closed operating state to represent at least one defined operating state of the transmission device (1), during which a power flow between a transmission input shaft (2) and a transmission output shaft (3) is present, wherein, when there is a request to close the positive shifting element (A, F), a rotational speed (nt) of the transmission input shaft (2) or a rotational speed equivalent thereto is guided in the direction of a synchronous rotational speed (nt("4")), which is established in the closed operating state of the positive shifting element (F) at least as a function of the rotational speed of the transmission output shaft (3),wherein the engagement process of the positive-locking switching element (F) in the open operating state is aborted when the profile of the rotational speed (nt) of the transmission input shaft (2) or the rotational speed equivalent thereto crosses a predefined rotational speed threshold (ntS3) after reaching the synchronous rotational speed (nt(“4”)) with the positive-locking switching element (F) actuated in the closing direction, characterized by that the engagement process of the positive switching element (A, F) is aborted if the course of the speed (nt) of the transmission input shaft (2) or the speed equivalent thereto crosses an additional predefined speed threshold (ntS1) before reaching the synchronous speed (nt(“4”)), without actuation of the positive switching element (A, F) in the closing direction being requested. [2] Method according to claim 1, characterized bythat a timer is started when the curve of the speed (nt) of the transmission input shaft (2) or the speed equivalent thereto, after reaching the synchronous speed (nt(“4”)), crosses a further predefined speed threshold (ntS4) before the predefined speed threshold (ntS3) when the positive-locking switching element (F) is actuated in the closing direction, wherein the switching process of the positive-locking switching element (F) in the open operating state is aborted when the value of the timer reaches a predefined value. [3] Method according to claim 1 or 2, characterized bythat a point in time (T4) is determined before reaching the synchronous speed (nt(“4”)), from which point in time an actuation of the positive switching element (F) acting in the closing direction of the positive switching element (F) is to be started, wherein the engagement process of the positive switching element (F) is aborted if the course of the speed (nt) of the transmission input speed or the speed equivalent thereto crosses the additional predefined speed threshold (ntS1) at a point in time (T9) which lies before the determined start of the actuation of the positive switching element (F) in the closing direction. [4] Method according to one of claims 1 to 3, characterized bythat the positive switching element (F) is actuated in the closing direction when the course of the speed (nt) of the transmission input shaft (2) or the speed equivalent thereto crosses an additional further predefined speed threshold (ntS2) which reaches the speed (nt) of the transmission input shaft or the speed equivalent thereto before the additional predefined speed threshold (ntS1). [5] Method according to one of claims 1 to 4, characterized by that the transmission device (1) is transferred into a safe operating state after the termination of the engagement process of the positive switching element (F), in which both the transmission input shaft (2) and the transmission output shaft (3) are rotatable. [6] Method according to claim 5, characterized bythat the safe operating state of the transmission device (1) corresponds to a neutral operating state in which the power flow between the transmission input shaft (2) and the transmission output shaft (3) is interrupted. [7] Method according to one of claims 5 or 6, characterized by that the safe operating state corresponds to the operating state of the transmission device (1) before the request to close the positive switching element (F). [8] Method according to one of claims 1 to 7, characterized by that the speed threshold (ntS3), the further speed threshold (ntS4), the additional speed threshold (ntS1) and / or the additional further speed threshold (ntS2) varies depending on an operating temperature of the transmission device (1). [9] Method according to one of claims 1 to 8, characterized bythat the speed threshold (ntS3), the further speed threshold (ntS4), the additional speed threshold (ntS1) and / or the additional further speed threshold (ntS2) varies depending on a gradient of a course of the difference between the currently existing speed (nt) of the transmission input shaft (2) and the synchronous speed (nt(“4”)) of the transmission input shaft (2) or the speed equivalent thereto.

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