Method and control unit for determining the operating state of a positive-locking switching element

Abstract

Method for determining an operating state of a positive-locking switching element (A, F) which has two switching element halves (10, 11) that can be positively engaged with each other, wherein at least one of the switching element halves (10) is adjustable between a first end position, which corresponds to an open operating state of the switching element (A, F), and a second end position, which corresponds to a closed operating state of the switching element (A, F), wherein a current position of the switching element half (10) is monitored by means of a sensor, characterized in that A sufficiently closed operating state of the switching element (A, F) for the transmission of a torque applied to the switching element (A, F) is detected when the sensor signal has a value greater than an applicable value for a defined period of time. which corresponds to a defined overlap between the switching element halves (10, 11), which is smaller than the overlap between the switching element halves (10, 11) when the adjustable switching element half (10) is arranged in its second end position, and if the adjustable switching element half (10) is additionally actuated and adjusted in the direction of the second end position, whereby a tooth-to-tooth position is detected when the sensor determines within an actuation range of the at least one movable switching element half (10) between an open state and a closed state of the switching element (A, F), that the positioning movement of at least one movable switching element half (10) in the closing direction is zero, a ratio between a closing force acting on the switching element (A, F) and a radial force acting on the switching element halves (10, 11), which results from a torque applied to the switching element (A, F), lies within a value range that favors a tooth-to-tooth position and a positioning movement of at least one movable switching element half (10) in the closing direction is detected by the sensor after a reduction of the closing force and / or after an increase in the applied torque.

Description

[0001] The invention relates to a method for determining the operating state of a positive-locking switching element according to the type defined in more detail in the preamble of claim 1. The invention further relates to a control unit for carrying out the method and a corresponding computer program.

[0002] From DE 10 2005 002 337 A1, a transmission designed as an 8-speed multi-stage transmission with friction-fit switching elements is known. The switching elements are designed as multi-plate clutches or multi-plate brakes. When a shift request for a gear ratio change occurs in the transmission, at least one of the friction-fit switching elements is disengaged from the power flow of the transmission device and at least one further friction-fit switching element is engaged in the power flow of the transmission device in order to transmit a torque.

[0003] Generally, when a friction-fit switching element is requested to open, it can be assumed that the friction-fit switching element will actually transition to the open operating state, regardless of the torque currently applied to the friction-fit switching element. Similarly, a request to close a friction-fit switching element can be implemented with comparatively little control effort.

[0004] For this reason, a simple software-based evaluation of the control current of a pressure regulator of a friction-fit switching element is sufficient. By determining a corresponding opening control signal or a corresponding closing control signal to transfer the friction-fit switching element to its open or closed operating state, it is easily verifiable via such an evaluation whether a switching or gear change was successful.

[0005] Unfortunately, friction-based switching elements in the open operating state cause drag torques, which impair the overall efficiency of an automatic transmission to an undesirable extent.

[0006] 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 friction-locking switching elements. Such positive-locking switching elements typically have two halves. The halves can be brought into positive engagement with each other by axially adjusting at least one movable half relative to the other, which is then axially fixed, in the area of ​​claw elements or the like. The positive-locking switching element is then closed and transmits an applied torque. Furthermore, it is also possible for both halves of the switching element to be axially movable relative to each other.

[0007] If the positive-locking switching element is to be deactivated from the power flow, the positive lock between the switching element halves is released by axially displacing the movable switching element half relative to the axially fixed switching element half. The reason for using positive-locking switching elements is that, unlike friction-locking switching elements, virtually no drag torques occur in the area of ​​open positive-locking switching elements, which would impair the overall efficiency of a transmission. However, it must be taken into account that, compared to friction-locking switching elements, positive-locking switching elements can only be converted from an open operating state, in which no torque can be transmitted via the positive-locking switching elements, to their closed operating state near their synchronization point.

[0008] Additionally, positive-locking switching elements integrated into the power flow of a transmission device can be disengaged from the power flow or moved to their open operating state with low switching forces if the applied torque is sufficiently low. During shifting operations or so-called gear selection processes, the power flow between a transmission input shaft and a transmission output shaft must be interrupted. In this process, a positive-locking switching element may need to be moved from its closed operating state to its open operating state. Due to an excessively rapid or faulty build-up of torque in the area of ​​the positive-locking switching element, or a faulty reduction of the applied torque, the positive-locking switching element may not be able to be moved to its open operating state.Furthermore, mechanical, hydraulic, or electrical malfunctions can prevent a positive-locking switching element from opening. Therefore, unlike friction-locking switching elements, positive-locking switching elements do not necessarily enter an open operating state when a corresponding opening control signal is present.

[0009] Additionally, it is possible that an open, positive-locking switching element cannot be converted to its closed operating state within the desired short operating times. This is the case, for example, if the desired positive lock between the switching element halves cannot be achieved due to a so-called tooth-on-tooth position. In such a tooth-on-tooth position, the claw elements of the switching element halves are in contact with each other at their end faces, and the differential rotational speed between the switching element halves is zero. Such a tooth-on-tooth position only breaks down when the torque applied to the positive-locking switching element is greater than the static friction torque between the end faces of the claw elements of the switching element halves.

[0010] Furthermore, the establishment of a complete positive lock or the complete closing of a positive-locking switching element can also be prevented by so-called flank clamping between the flanks of the claw elements. In such flank clamping, the two switching elements have a certain axial overlap in the area of ​​their claw elements. However, the static friction between the adjacent flanks of the claw elements of the switching element halves is so high that the closing force acting on the switching elements in the closing direction is insufficient to overcome the static friction and completely close the positive-locking switching element.

[0011] If a positive-locking switching element gets stuck in an intermediate position during a closing process—a position situated between a fully open and a fully closed operating state—various methods are used to resolve this undesirable intermediate position. The problem, however, is that the methods for resolving a tooth-on-tooth jamming or flank jamming differ significantly, and incorrect application can impair driving comfort and considerably increase switching times. This stems from the fact that the method for resolving a tooth-on-tooth jamming exacerbates flank jamming, while the method for resolving flank jamming perpetuates a tooth-on-tooth jamming.

[0012] Sensors are used to monitor the current operating state of a positive-locking switching element. These sensors typically include a permanent magnet and a measuring device for sensing the magnetic field of the permanent magnet. Additionally, the sensors incorporate a ferromagnetic encoder contour that influences the magnetic field of the permanent magnet depending on the operating states of the switching element halves. Various magnetic field-sensing elements are known, such as Hall effect-based elements or magnetic resistance elements. Magnetic field sensors generally include magnetic field-sensing elements or other electronic components, with some magnetic field sensors incorporating permanent magnets in a so-called back-biased arrangement.

[0013] These magnetic field sensors provide electrical signals that reflect the state of a sensed magnetic field. In some designs, magnetic field sensors interact with ferromagnetic objects. The sensors detect magnetic field fluctuations caused by an object moved through the magnetic field of the sensor's magnet. The magnetic field monitored by the sensor also varies depending on the shape or profile of the moving ferromagnetic object. The position of the switching element halves is calculated directly from the raw sensor signals using applicable thresholds.

[0014] Unfortunately, this approach means that all tolerances of the sensor and the sensing system, as well as production-related variations, influence the position determination. This results in the position determination of the switching element halves not having the accuracy required for the operation of a gearbox.

[0015] The lack of accuracy in determining the position of the switching element halves relative to each other during an opening or closing process also means that if a positive-locking switching element gets stuck, especially during a closing process, the correct procedure for resolving the intermediate position of the switching element may not be carried out.

[0016] An additional disadvantage is that the positive-locking switching element is only subjected to the torque to be transmitted after the fully engaged operating state of the element has been successfully determined. Before the fully closed operating state is determined, no significant torque is applied to the positive-locking switching element to prevent damage.

[0017] This procedure is also used when a positive-locking switching element is in its almost completely closed operating state and the claw elements of the switching element half largely overlap.

[0018] Positive-locking switching elements are designed such that a defined torque can be transmitted even with partial overlap of the switching element halves, without irreversibly damaging the positive-locking switching element. If a requested closing operation of a positive-locking switching element lasts longer than a defined switching time, actuation routines are initiated to bring the positive-locking switching element into its full operating state. However, these actuation routines impair switching quality.

[0019] Also known are comparable methods for a control arrangement for a switching element, as well as control devices for this control arrangement, as disclosed in DE 10 2017 201 753 A1 and DE 10 2013 222 381 A1.

[0020] Based on the prior art described above, the invention aims to provide a method for determining the operating state of a positive-locking switching element, enabling the actuation of such an element with high switching quality within short switching times. Additionally, a control unit designed to carry out the method and a computer program for carrying out the method are described.

[0021] From a process engineering perspective, this problem is solved starting from the preamble of claim 1 in conjunction with its characterizing features. A control unit and a computer program product are also the subject of the further independent claims. Advantageous embodiments are the subject of the dependent claims and the following description.

[0022] A method for determining the operating state of a positive-locking switching element is proposed. The switching element has two halves that can be positively engaged with each other. At least one of the halves is adjustable between a first end position, corresponding to an open operating state of the switching element, and a second end position, corresponding to a closed operating state. The current position of the half is monitored by means of a sensor.

[0023] The term "positive locking switching element" here refers, for example, to claw switching elements, each of which transmits torque via a positive locking connection. Furthermore, the term "friction-locking switching element" here refers to switching elements designed as clutches or brakes, each of which transmits torque via a friction-locking connection. The torque that can be transmitted via such a friction-locking switching element varies depending on the closing force applied to the element and is preferably continuously adjustable. The closing force corresponds, for example, to a hydraulic pressure applied to the switching element. In contrast, the torque that can be transmitted via a positive locking switching element is not continuously adjustable.

[0024] The invention now comprises the technical teaching that a sufficiently closed operating state of the switching element for the transmission of a torque applied to the switching element is detected when the sensor signal has a value greater than an applicable value for a defined period. The applicable value corresponds to a defined overlap between the switching element halves, which is smaller than the overlap between the switching element halves when the adjustable switching element half is arranged in its second end position.Furthermore, the degree of overlap sufficient for transmission between the switching element halves is detected when the adjustable switching element half is additionally controlled and adjusted in the direction of the second end position, whereby a tooth-to-tooth position is detected when, via the sensor, within an actuation range of the at least one movable switching element half between an open state and a closed state of the switching element, it is determined that the actuation movement of the at least one movable switching element half in the closing direction is zero, a ratio between a closing force applied to the switching element and a radial force acting on the switching element halves. which results from a torque applied to the switching element, lies within a value range that favors a tooth-to-tooth position, and which, after a reduction of the closing force and / or after an increase in the applied torque, detects an actuating movement of at least one movable half of the switching element in the closing direction via the sensor.

[0025] In the inventive procedure, preferably datable threshold values ​​are used for determining the operating state or the switching path of the movable switching element half, which lie before the end position and indicate a sufficient degree of overlap between the switching element halves.

[0026] Sufficient tooth coverage of a positive-locking switching element is detected when the current switching travel value of the movable switching element half is within the range of sufficient partial coverage for a dataable time.

[0027] This minimal partial coverage can be determined, for example, using application techniques and ensures the long-term durability of a positive-locking switching element.

[0028] When such an overlap between the halves of a positive-locking switching element is detected, a transmission control unit, for example, receives information about the status of the positive-locking switching element, indicating that it is in an operating state at least approximately equivalent to a fully closed state. Furthermore, information is transmitted that the switching element is capable of transmitting an applied torque. Additionally, the transmission control unit also receives information indicating that the positive-locking switching element is only in a partially overlapped operating state.

[0029] Using this method, the closing process of a positive-locking switching element is completed within short operating times, eliminating the need for additional measures that are typically activated to fully close such an element. This is advantageous because such additional measures are known to affect switching quality and undesirably extend the switching times of positive-locking switching elements.

[0030] The term "dataable" in combination with a value, an adaptation value, an operating parameter, a threshold value, a time value or the like, refers to a parameter or value whose size and value can be changed without having to reprogram or reinstall the control unit software.

[0031] In an advantageous embodiment of the method according to the invention, when movement of the adjustable switching element half towards the first end position is detected, the torque applied to the switching element is reduced and the actuating force acting in the closing direction is increased. This, in turn, ensures that the positive-locking switching element is brought into its closed operating state to the required extent.

[0032] If the applicable value is varied depending on the torque applied to the switching element, the value of the partial overlap becomes more accurate and the minimum overlap between the switching element halves can be specified with less tolerance allowance.

[0033] This approach offers the advantage that scaling the partial coverage also allows for scaling the respective transmissible torque.

[0034] For example, with a partial overlap of 50%, a torque corresponding to approximately 30% of the maximum transmissible torque could be transmitted via the positive-locking switching element. Depending on the specific application, a partial overlap of 60% might be suitable for transmitting 50% of the maximum torque.

[0035] In an advantageous embodiment of the method according to the invention, a tooth-to-tooth position is detected when the sensor determines, within a travel range of the at least one movable switching element half between an open state and a closed state of the switching element, that the movement of the at least one movable switching element half in the closing direction is zero. Furthermore, it is checked whether the ratio between a closing force acting on the switching element and a radial force acting on the switching element halves, resulting from a torque applied to the switching element, lies within a range of values ​​within which a tooth-to-tooth position is highly likely to occur.Furthermore, a tooth-to-tooth position is determined when, after reducing the closing force and / or increasing the applied torque, a positioning movement of at least one movable switching element half in the closing direction is detected via the sensor.

[0036] Using this method, it is easy to clearly distinguish whether the positive-locking switching element was not moved to the required extent towards the closed or open operating state during an actuation due to a tooth-on-tooth position or due to flank clamping within the current actuation range.

[0037] With precise knowledge of the travel range between two halves of a positive-locking switching element, within which a tooth-on-tooth position occurs, the measure intended to resolve the tooth-on-tooth position can be triggered and the tooth-on-tooth position can be terminated to the desired extent. This allows, for example, a switching operation within a gearbox in which the positive-locking switching element is involved to be implemented easily and within short switching times.

[0038] Additionally, if the switching element cannot be brought into its closed operating state to the required extent due to flank clamping, the flank clamping can be resolved by appropriate measures, allowing the positive-locking switching element to be brought into its closed operating state within a short operating time. For example, if flank clamping occurs when the detected overlap exceeds a certain threshold, it may be possible to forego any measure to resolve the flank clamping altogether. This threshold corresponds to an overlap limit above which the torque applied or to be applied to the positive-locking switching element can be transmitted via the positive-locking switching element without causing unacceptably high loads in the flank area.

[0039] In an advantageous embodiment of the method according to the invention, the determination of the travel range between the switching element halves is initiated when the sensor detects that the movement of at least one movable switching element half in the closing direction is zero. However, the determination of the travel range between the switching element halves is only initiated when a sensor signal, within a period equal to or longer than a predefined period, is greater than or equal to a predefined lower threshold and less than or equal to a predefined upper threshold.

[0040] This means that the determination of the adjustment range is only carried out when the presence of a tooth-to-tooth position is probable and the intermediate position for which the determination is carried out is characterized by sufficient stability.

[0041] When the determination of the travel range corresponding to a tooth-to-tooth position between the switching element halves is carried out for the first time, then the minimum value of the sensor signal and the maximum value of the sensor signal limit the travel range between the switching element halves in an advantageous variant of the method according to the invention.

[0042] This means that the two extreme values ​​determined for the first time via the sensor form the limits of the adjustment range of the switching element half, within which a tooth-to-tooth position can be expected.

[0043] In a further advantageous embodiment of the method according to the invention, the limits of the travel range are changed depending on further values ​​of the sensor signal, if these further values ​​of the sensor signal deviate from the previously determined values ​​of the sensor signal by more than a threshold value. These further values ​​of the sensor signal are determined during further measurements of the travel range between the switching element halves for a detected tooth-to-tooth position.

[0044] Using this approach, the range of travel can be increased or extended with minimal effort by determining smaller minimum positions and / or larger maximum positions of the switching element half.

[0045] In a further advantageous embodiment of the method according to the invention, the limits of the travel range are varied depending on the currently determined values ​​of the sensor signal. The sensor signal values ​​are changed when the difference between the travel range defined by the currently determined sensor signal values ​​and the previously determined travel range is less than or equal to a predefined threshold. This provides a simple way to verify whether the previous travel range (tooth-to-tooth range) and the newly detected travel range (tooth-to-tooth range) are too far apart.

[0046] If the adjustment ranges are too far apart and the previously determined adjustment range was defined based on a number of detected tooth-to-tooth positions that is less than a threshold value, then, in a further advantageous embodiment of the method according to the invention, the limits of the previously determined adjustment range are discarded. The adjustment range is then redefined when a tooth-to-tooth position is subsequently detected.

[0047] This in turn easily avoids miscalculating the range of motion when only a small number of tooth-to-tooth positions have been detected.

[0048] In an advantageous embodiment of the inventive method, the determination of the travel range is ensured with the desired high accuracy over the lifetime of the positive-locking switching element. For this purpose, the travel range is increased by varying the limits depending on the determined values ​​of the sensor signal until the distance between the limits of the travel range is greater than or equal to a predefined maximum value.

[0049] In one variant of the inventive method, the minimum and maximum sensor signal values ​​determined for each tooth-to-tooth position are compared to the limits of a travel range that has already been defined based on a number of determined tooth-to-tooth positions greater than a threshold value. The limits of the travel range are increased or decreased by an offset if the determined minimum and maximum sensor signal values ​​deviate from the lower or upper limit of the travel range by values ​​greater than a threshold value.

[0050] In one variant of the inventive method, the limits of the travel range are varied depending on the minimum or maximum sensor signal value determined for a tooth-to-tooth position. This occurs when the distance between the limits of the travel range has already reached or exceeded the maximum value and the minimum or maximum sensor signal value lies outside the travel range. The limits of the travel range are then adjusted so that the distance between the limits of the adjusted travel range does not substantially exceed the maximum distance. This ensures that tooth-to-tooth position detection is achieved with minimal effort and the desired high accuracy over the service life of a positive-locking switching element.

[0051] In a further advantageous embodiment of the method according to the invention, two actuation ranges are determined starting from two predefined actuation ranges between the overlapping switching element halves. This is the case when each of the switching element halves is designed with two groups of claw elements. The first group of claw elements has a greater length in the actuation direction of at least one movable switching element half than the claw elements of the second group. Additionally, the claw elements of the two groups are arranged alternately next to each other in the circumferential direction of the switching element halves.

[0052] This allows tooth-to-tooth positions of such a positive-locking switching element, which can occur both between the longer claw elements of the switching element half and between the longer claw elements of one switching element half and the shorter claw elements of the other switching element half, to be determined to the desired extent with minimal effort.

[0053] It is possible to adjust the limits of the travel ranges until all sensor signal values ​​determined for tooth-to-tooth positions and lying within the overlap of the two travel ranges are assigned to only one of the two travel ranges. This, in turn, ensures that tooth-to-tooth positions for the aforementioned operating states of a switching element equipped with a so-called catch-tooth claw can be assigned to either one travel range or the other.

[0054] A further advantageous embodiment of the inventive method avoids erroneous readings with minimal effort. For this purpose, the travel range is provided to have a minimum width that corresponds to a value range for sensor signals determined for tooth-to-tooth positions between the longer claw elements of the switching element halves. The minimum width of this travel range is designed such that it encompasses the minimum and maximum signal values ​​determined for each tooth-to-tooth position. Additionally, the minimum width is also determined based on signal deviations resulting from load-induced movements of the entire switching element relative to the sensor and from tolerance-related sensor behavior.

[0055] The invention further relates to a control unit configured to carry out the method according to the invention. The control unit comprises, for example, means that serve to carry out the method according to the invention. These means can be hardware-related means and software-related means. The hardware-related means of the control unit or control device are, for example, data interfaces for exchanging data with the assemblies of the vehicle powertrain involved in carrying out the method according to the invention. Other hardware-related means are, for example, a memory for data storage and a processor for data processing. Software-related means can include, among other things, program modules for carrying out the method according to the invention.

[0056] The control unit can be configured to carry out the method according to the invention with at least one receiving interface, which is designed to receive signals from signal transmitters. The signal transmitters can, for example, be designed as sensors that detect measured quantities and transmit them to the control unit. A signal transmitter can also be referred to as a signal sensor. The receiving interface can thus receive a signal from a signal transmitter indicating that an operating state of a positive-locking switching element is to be determined. The signal can be generated by a driving strategy that is activated and executed in the area of ​​the control unit or in the area of ​​another control unit of a transmission or a vehicle powertrain.

[0057] The control unit may also have a data processing unit to evaluate and / or process the received input signals or the information contained in the received input signals.

[0058] The control unit can also be equipped with a transmission interface designed to output control signals to actuators. An actuator is a device that implements the commands from the control unit. These actuators can be, for example, electromagnetic valves.

[0059] If, during the actuation of the positive-locking switching element, the control unit detects, or determines based on received input signals, that an operating state of the positive-locking switching element needs to be determined, then the control unit uses the detected input signals to define a corresponding request and triggers the corresponding determination. The positive-locking switching element has two switching element halves that can be positively engaged with each other, with at least one of the switching element halves being adjustable between a first end position and a second end position. The first end position corresponds to an open operating state, and the second end position corresponds to a closed operating state of the switching element. The current position of the switching element half is monitored by means of a sensor.

[0060] The control unit is designed in such a way that a sufficiently closed operating state of the switching element for the transmission of a torque applied to the switching element is detected when the signal of the sensor has a value greater than an applicable value for a defined period of time.

[0061] The applicable value corresponds to a defined overlap between the switching element halves, which is smaller than the overlap between the switching element halves when the adjustable switching element half is in its second end position.Furthermore, the control unit determines the sufficiently closed operating state for the transmission of a torque applied to the switching element when the adjustable switching element half is additionally controlled and adjusted in the direction of the second end position, whereby a tooth-to-tooth position is detected when, via the sensor, within an actuation range of the at least one movable switching element half between an open state and a closed state of the switching element, it is determined that the actuation movement of the at least one movable switching element half in the closing direction is zero, a ratio between a closing force applied to the switching element and a radial force acting on the switching element halves. which results from a torque applied to the switching element, lies within a value range that favors tooth-to-tooth positioning, and which, after a reduction in the closing force and / or an increase in the applied torque, detects an actuating movement of at least one movable half of the switching element in the closing direction via the sensor.

[0062] This ensures that a positive-locking switching element is subjected to a transmitted torque even when it is not yet in its fully closed operating state. This offers the advantage that a switching operation involving a positive-locking switching element can be carried out within short operating times while maintaining a high level of shifting comfort. This advantage arises from the fact that known actuation routines, by means of which a switching element that is not fully closed is brought into its fully closed operating state, are no longer necessary. Since such actuation routines significantly impair shifting comfort, they should only be activated or executed to prevent undefined operating states of a transmission equipped with a positive-locking switching element.

[0063] The aforementioned signals are merely examples and are not intended to limit the invention. The acquired input signals and the output control signals can be transmitted via a vehicle bus, for example, a CAN bus. The control device or control unit can be designed, for example, as a central electronic control unit of the vehicle powertrain or as an electronic transmission control unit.

[0064] The solution according to the invention can also be embodied as a computer program product which, when running on a processor of a control device, instructs the processor by means of software to carry out the associated process steps relating to the invention. In this context, a computer-readable medium on which a computer program product described above is stored in a retrievable manner is also part of the subject matter of the invention.

[0065] The invention is not limited to the specified combination of features of the dependent or suffixed claims. Furthermore, it is possible to combine individual features, even those apparent from the claims, the subsequent description of embodiments, or directly from the drawings. References in the claims to the drawings by means of reference numerals are not intended to limit the scope of protection of the claims.

[0066] Preferred embodiments are described in the dependent claims and the following description. An exemplary embodiment of the invention is explained in more detail with reference to the drawing, without being limited thereto. The drawing shows: Fig. 1 a schematic representation of a vehicle drive train with a drive motor, a transmission and an output; Fig. 2 a tabular switching logic of the in Fig. 1 of the gearbox shown; Fig. 3a to Fig. 3e each different operating states of a highly schematically represented positive-locking switching element between a fully open state and a fully closed state; Fig. 4a to Fig. 4f each Fig. 3a corresponding representations of different operating states of a positive locking switching element whose claw elements are designed with different lengths; Fig. 5a a positioning path of the positive locking switching element according to Fig. 4a between a fully closed state and a fully open operating state as well as a first predefined travel range and a second predefined travel range within which tooth-to-tooth positions between longer claw elements and between longer and shorter claw elements of the switching element halves are expected; Fig. 5b to Fig. 5d each one Fig. 5a corresponding representation, wherein the limits of the adjustment ranges are successively adjusted so that sensor signals corresponding to tooth-to-tooth positions are increasingly assigned to only one of the adjustment ranges; Fig. 6a to Fig. 6d Graphical representations of a further procedure, such as travel ranges for tooth-to-tooth positions of a positive locking switching element according to Fig. 4a can be determined exactly; Fig. 7a to Fig. 7f each one Fig. 6a to Fig. 6d corresponding representation of a further procedure, such as travel ranges for tooth-to-tooth positions of a switching element according to Fig. 4a can be determined with the desired accuracy; and Fig. 8a and Fig. 8b a Fig. 6a to 6d corresponding representation of a further procedure for the defined determination of travel ranges for tooth-to-tooth positions of a switching element according to Fig. 4a.

[0067] Fig. Figure 1 shows a schematic representation of a vehicle powertrain 1 with a drive engine 2, a transmission 3, and an output 4. The drive engine 2 is an internal combustion engine. The transmission 3 is an automatic transmission with multiple gear ratios "1" to "9" for forward travel and at least one gear ratio "R" for reverse travel. Depending on the configuration of the vehicle powertrain 1, the output 4 comprises one, two, or more driven axles, which can be supplied with the torque of the drive engine 2 via the transmission 3. During a gear change in the transmission 3, i.e., during upshifts or downshifts, hydraulically actuated shift elements A to F are activated. These gear changes should be performed essentially without interruption of traction, while maintaining high driving comfort and the desired performance.The term "performance" refers to each gear ratio change in gearbox 3 that is implemented within a defined operating time.

[0068] In order to carry out the requested switching to the desired extent, the switching elements A to F are each subjected to switching sequences stored in a transmission control unit and a corresponding switching pressure.

[0069] The transmission 3 comprises a transmission input shaft 5 and a transmission output shaft 6. The transmission output shaft 6 is connected to the output shaft 4. A torsional damper 7 and a hydrodynamic torque converter 8 with an associated converter lock-up clutch 9 are arranged between the transmission input shaft 5 and the drive motor 2.

[0070] Furthermore, the transmission 3 comprises four planetary gear sets P1 to P4. The first planetary gear set P1 and the second planetary gear set P2, which are preferably designed as negative planetary gear sets, form a switchable intermediate gear set. The third planetary gear set P3 and the fourth planetary gear set P4 constitute a so-called main gear set. The switching elements C, D, and F of the transmission 3 are designed as brakes, while the switching elements A, B, and E are so-called shift clutches.

[0071] The switching elements A to F are used according to the in Fig. The switching logic described in more detail in section 2 enables selective switching of the transmission stages "1" to "R". To establish a power flow in the transmission, essentially three of the switching elements A to F must be simultaneously brought into or held in a closed operating state.

[0072] The switching elements A and F are designed as positive-locking switching elements without additional synchronization. As a result, in transmission 3, compared to transmissions designed only with friction-locking switching elements, the drag torques caused by open friction-locking switching elements are reduced.

[0073] As is known, positive-locking switching elements can generally only be switched from an open to a closed operating state within a very narrow differential speed range between the switching element halves to be positively engaged, around the synchronous speed. If the synchronization of an additional positive-locking switching element cannot be achieved by means of additional design features, synchronization is realized by corresponding actuation of the other friction-locking switching elements involved in the circuit and / or by a so-called motor engagement. During such a motor engagement, for example, the drive torque provided by the drive motor 2 is varied to the extent required for synchronization in both the push and pull modes of the vehicle drive train 1.This also applies to the actuation of the friction-locking switching elements during the execution of requested pull or push switching operations.

[0074] Fig. 3a to Fig. Figure 3e shows two switching element halves 10, 11 of the positive-locking switching element A and F, respectively, in different operating states. In this case, Fig. 3a shows the fully open operating state of the positive locking switching element A or F, in which there is no positive locking between the two switching element halves 10 and 11 and in which the switching element halves 10 and 11 are spaced apart from each other in axial direction x.

[0075] The switching element halves 10 and 11 each comprise claw elements 10A and 11A. Depending on the specific application, the claw elements 10A and 11A can be brought into positive engagement with each other by axially adjusting the switching element half 10 and / or the switching element half 11 relative to the switching element half 11 or the switching element half 10, in order to transmit a torque applied to the positively locking switching element A or F to the desired extent.

[0076] When a corresponding requirement to close the positive-locking switching element A or F is met, a corresponding actuating force in the closing direction is applied to the respective slidably designed switching element half 10 or 11. This results in the axial distance between the opposing end faces 10B and 11B of the claw elements 10A and 11A being progressively reduced.

[0077] If the differential rotational speed between the switching element halves 10 and 11 is too large, the claw elements 10A and 11A cannot be positively engaged with each other. In such a case, a so-called ratcheting occurs, during which the claw elements 10A and 11A are disengaged in the Fig. The circumference shown in Figure 3b is such that the claw elements 10 and 11 slide against each other in the circumferential direction of their facing end faces 10B and 11B. However, such ratcheting is undesirable, as it causes irreversible damage to the claw elements 10A and 11A over time.

[0078] For this reason, the differential speed between the switching element halves 10 and 11 is adjusted to values ​​within a differential speed window around the synchronous speed of the positive-locking switching element A or F by appropriately actuating the friction-locking switching elements B to E involved in the change of operating state in the gearbox 3. Within this differential speed window, the claw elements 10A and 11A of the switching element halves 10 and 11 can be positively engaged with each other to the desired extent.

[0079] However, it should be noted that the required positive locking can be prevented by a so-called tooth-on-tooth alignment between the switching element halves 10 and 11. The tooth-on-tooth alignment is as described in Fig. Figure 3c is characterized by the fact that the claw elements 10A and 11A are in contact with each other in the region of their end faces 10B and 11B, and the differential rotational speed between the switching element halves 10 and 11 is zero. During such a tooth-to-tooth position of the positive-locking switching element A or F, the static friction between the end faces 10B and 11B of the claw elements 10A and 11A is so high that the torque applied to the positive-locking switching element A or F is transmitted via the positive-locking switching element A or F without the tooth-to-tooth position being released.

[0080] To resolve the tooth-on-tooth misalignment, it is advantageous to reduce the actuating force applied to the positive-locking switching element A or F in the closing direction and / or to increase the torque applied to the positive-locking switching element A or F. Reducing the closing force lowers the static friction in the area between the end faces 10B and 11B of the claw elements 10A and 11A. Simultaneously, increasing the torque applied to the positive-locking switching element A or F overcomes the static friction between the end faces 10B and 11B, and increases the differential rotational speed between the switching element halves 10 and 11 to a degree sufficient to establish a positive-locking connection between the claw elements 10A and 11A.

[0081] In Fig. Figure 3d shows an operating state of the positive-locking switching element A or F in which a positive lock exists between the switching element halves 10 and 11 with a so-called partial overlap of the claw elements 10A and 11A. Such an operating state exists both during an opening process and during a closing process of the positive-locking switching element A or F.

[0082] The torque acting on the switching element A or F, combined with the coefficients of friction of the flanks 10C and 11C, results in a static friction force acting between the flanks 10C and 11C. If the actuating force acting on the switching element halves 10 and 11 in the opening or closing direction of the positive-locking switching element A or F is too low relative to the static friction force between the flanks 10C and 11C of the claw elements 10A and 11A, so-called flank clamping occurs. During such flank clamping, the axial relative positioning movement between the switching element halves 10 and 11 in the closing or opening direction is zero, thus preventing the requested change of operating state of the positive-locking switching element A or F. To avoid or resolve such flank clamping, for example the actuating force applied to the switching element A or F can be increased and / or the positive locking of the switching element A or F can be adjusted.The torque applied to each of these areas will be reduced to the necessary extent.

[0083] The fully closed operating state of the positive-locking switching element A or F is in Fig. 3e is shown, in which there is full overlap between the claw elements 10A and 11A in the axial direction x.

[0084] Fig. 4a to Fig. 4f each show one Fig. 3a shows a corresponding representation of the positive-locking switching element A or F. In switching element A or F, the claw elements 10A and 11A of the switching element halves 10 and 11, which are arranged next to each other in the circumferential direction of the switching element halves 10 and 11, each have a different length in the axial direction x. The longer claw elements are subsequently identified by reference numerals 10A1 and 11A1, and the shorter claw elements by reference numerals 10A2 and 11A2.

[0085] This design of the positive-locking switching elements A and F offers the advantage that the positive locking between the switching element halves 10 and 11 can be achieved at higher differential rotational speeds between the switching element halves 10 and 11 than with the design in Fig. 3a to Fig. 3e depicted embodiment of the positive-locking switching elements A and F. In contrast, the embodiment of the positive-locking switching element A or F according to Fig. 4a to Fig. 4f compared to the design of the positive locking switching element A or F according to Fig. 3a to Fig. 3e exhibits lower robustness compared to ratchets.

[0086] Due to the differently lengthened claw elements 10A1, 10A2 and 11A1 and 11A2, the switching element A or F can be used in addition to the Fig. 3a to Fig. 3e described operating states of the positive-locking switching element A or F exhibit further operating states, which are described in the following section. Fig. 4a to Fig. 4f will be discussed in more detail.

[0087] First, in Fig. 4a again shows the fully open operating state of the switching element A or F. Fig. Figure 4b again shows the operating state of the positive-locking switching element A or F during ratchet operation. During ratchet operation, the switching element halves 10 and 11 slide against each other circumferentially in the area of ​​the end faces 10B1 and 11B1 of the longer claw elements 10A1 and 11A1. Thus, the positive locking between the switching element halves 10 and 11 cannot be established. This ratchet operation is again described in the following. Fig. The extent described in 3b can be avoided or terminated by reducing the differential rotational speed between the switching element halves 10 and 11.

[0088] Furthermore, they show Fig. 4c and Fig. 4d each has a tooth-to-tooth position that prevents the formation of a positive connection between the switching element halves 10 and 11. This is due to the fact that in Fig. In the operating state of the positive-locking switching element A or F shown in Figure 4c, the tooth-to-tooth position exists between the end faces 10B1 and 11B1 of the longer claw elements 10A1 and 11A1. In contrast, the tooth-to-tooth position between the switching element halves 10 and 11 is shown in Figure 4c. Fig. 4d shows the operating state of the positive locking switching element A or F between the end faces 11B1 of the longer claw elements 11A1 of the switching element half 11 and the end faces 10B2 of the shorter claw elements 10A2 of the switching element half 10.

[0089] Regardless of this, the respective tooth-to-tooth position between the switching element halves 10 and 11 is in the Fig. The problem can be resolved or avoided in the manner described in 3c.

[0090] Fig. Figure 4e shows an intermediate operating state of the positive-locking switching element A or F between the fully open operating state and the fully closed operating state of the positive-locking switching element A or F. During this intermediate operating state, the edge clamping described above can again occur between the claw elements 10A1, 10A2 and the claw elements 11A1, 11A2. The edge clamping is again in the Fig. The extent described in 3d can be avoided or resolved in order to open or close the positive locking switching element A or F to the required extent.

[0091] The fully closed operating state of the positive-locking switching element A or F is in Fig. 4f shown.

[0092] The following describes an advantageous procedure by which an actuation range between the two switching element halves 10 and 11 of the positive-locking switching element A or F is defined according to Fig. 3a can be determined within which the in Fig. The tooth-on-tooth position shown in 3c can occur. For this, the positive-locking switching element A or F is first moved starting from the point shown in Fig. 3a shown open operating state with an actuating force in the direction of the Fig. The closed operating state shown in Figure 3e is applied. As the operating time increases, the movable switching element half 10 is moved in the axial direction x towards the axially non-movable switching element half 11.

[0093] If the sensor assigned to the respective positive-locking switching element A or F detects that the positioning movement of the switching element half 10 is zero, a timer is started, and then it is checked whether the switching element half 10 remains in its current position for a predefined period. Additionally, the sensor signal is monitored. If the sensor signal does not fall below a predefined lower limit and does not exceed a predefined upper limit for the predefined period, a certain stability of the sensor signal is determined, and the intermediate position of the positive-locking switching element A or F is considered sufficiently stable. This evaluation triggers an adaptation process by which a predefined standard positioning range is adjusted to the actual system, which comprises the positive-locking switching element A or F and its respective assigned sensor.

[0094] First, a ratio is calculated between the closing force acting on the positive-locking switching element A or F and a radial force acting on the switching element A or F. This allows for a high probability determination of whether the switching element remains in the intermediate position and cannot be moved into the closed operating state due to tooth-to-tooth contact or flank clamping. The radial force results from the torque applied to the positive-locking switching element A or F. Additionally, it is checked whether the switching element A or F has left the intermediate position, from which it could not initially be moved into the closed state, using the previously described method for releasing a tooth-to-tooth contact or the procedure for releasing a flank clamp.

[0095] The ratio between the axial actuation force and the radial force acting on the positive-locking switching element A or F is within a range that favors a tooth-to-tooth engagement. Furthermore, the intermediate position of the positive-locking switching element A or F was resolved by the procedure used to terminate a tooth-to-tooth engagement. Therefore, a tooth-to-tooth engagement is determined for the intermediate position.

[0096] In this context, a tooth-to-tooth engagement range of the ratio between the axial and radial forces represents force ratios such that the static friction force in the area between the end faces 10B and 11B of the switching element halves 10 and 11 is greater than the radial force resulting from the applied torque. In such an operating state of the positive-locking switching element A or F, the applied torque is transmitted by the frictional engagement between the switching element halves 10 and 11 in the area of ​​the end faces 10B and 11B, whereby the relative rotational movement between the switching element halves 10 and 11 is then zero.

[0097] Furthermore, before determining the travel range between the two switching element halves 10 and 11 of the positive-locking switching element A or F, it is checked whether the adaptation for the first detected tooth-to-tooth position takes place, whether some tooth-to-tooth positions have already been detected, or whether a certain number of tooth-to-tooth positions greater than a threshold value have already been determined.

[0098] If the adaptation is performed based on the first detected tooth-to-tooth position, the minimum and maximum values ​​of the sensor signal define the limits of the adjustment range or the tooth-to-tooth range. These values ​​are temporarily stored and used as reference values ​​for later adaptations.

[0099] The procedure described above is performed each time the sensor detects a standstill of the axially movable switching element half 10 during a closing operation of the positive-locking switching element A or F. If a tooth-to-tooth position is detected with a high probability based on the test criteria mentioned above, the buffered limits of the travel range are compared to the minimum and maximum sensor signal values ​​determined for the currently detected tooth-to-tooth position of the positive-locking switching element A or F.

[0100] The adjustment range or tooth-to-tooth range is increased if the current sensor signal values ​​are smaller or larger than the previous limits of the adjustment range. First, however, a check is performed to ensure that the previous tooth-to-tooth range and the newly determined adjustment range are not too far apart. If this is the case, the currently determined tooth-to-tooth range and the previously learned tooth-to-tooth range or adjustment range are deleted.

[0101] If a tooth-to-tooth position is again determined during a further closing process of the positive locking switching element A or F, the minimum and maximum values ​​of the sensor signal determined for this purpose are stored as new limits of the actuation range.

[0102] This procedure is carried out as long as the number of detected tooth-on-tooth misalignments is less than a predefined value.

[0103] If the travel range between the two switching element halves 10 and 11 of the positive-locking switching element A or F has already been determined and adapted to be larger than the predefined value for a defined number of detected tooth-to-tooth positions, the minimum and maximum values ​​of the sensor signal determined for each detected tooth-to-tooth position are compared with the travel range. If the currently determined minimum and / or maximum value of the sensor signal lies outside the travel range, the limits of the travel range are increased by an offset in the corresponding direction. This continues until the lower and upper limits of the travel range have a maximum distance from each other.

[0104] If this is the case, and the upper limit of the travel range is to be raised or the lower limit of the travel range reduced, then the lower limit is raised by the same increment or the upper limit is reduced by the same increment. This implements the requested adjustment without further increasing the width of the travel range.

[0105] Fig. 5a to Fig. Figure 5d shows a graphical representation of an adaptation process of two predefined actuator ranges SWO and SWU to the actual gearbox 3. This is shown in relation to the representations according to... Fig. 5a to Fig. 5d below describes in more detail how reference values ​​LS and LS1 of the sensor of the switching element A or F for tooth-to-tooth positions of the positive locking switching element A or F are determined according to Fig. 4a can be clearly assigned to the upper travel range SWO or the lower travel range SWU. The upper travel range SWO defines a travel range of the movable switching element half 10 relative to the switching element half 11, which is not movable in the axial direction x, within which a Fig. The tooth-to-tooth position shown in 4c between the axially longer claw elements 10A1, 11A1 of the switching element halves 10, 11 is probable. At the same time, the lower travel range SWU of the switching element half 10 defines a travel range within which it is highly probable that Fig. 4d shows tooth-to-tooth positions between the longer claw elements 10A1 and 11A1 of the switching element half 10 and 11 respectively and the shorter claw elements 10A2 and 11A2 of the switching element half 10 and 11 respectively.

[0106] The starting point is the in Fig. Figure 5a shows the actuation ranges SWO and SWU, which are predefined standard actuation ranges. These two actuation ranges, SWO and SWU, have a smaller width than the entire actuation range of the switching element half 10, which extends from 0% to 100%. The positive-locking switching element A or F is fully open when the actuation range is 0%. When the switching element half 10 is fully displaced and its actuation range is 100%, the positive-locking switching element A or F is fully closed. The predefined upper actuation range SWO has a lower limit SWOL and an upper limit SWOU. Furthermore, the width of the predefined lower actuation range SWU is defined by the lower limit SWUL and the upper limit SWUU.The lower limit SWUL of the lower travel range SWU and the upper limit SWOU of the upper travel range SWO are defined such that the upper travel range SWO and the lower travel range SWU overlap.

[0107] The vertical lines LS drawn in the upper travel range SWO and the further vertical lines LS1 drawn in the overlap area of ​​the two travel ranges SWO and SWU correspond to values ​​of the sensor signal, which are used for detected tooth-to-tooth positions of the positive locking switching element A or F according to Fig. 4a were determined.

[0108] Since the sensor values ​​corresponding to the lines LS can be clearly assigned to the upper travel range SWO, it is assumed that the tooth-to-tooth positions each correspond to the one in Fig. The tooth-to-tooth position shown in Figure 4c between the longer claw elements 10A1 and 11A1 corresponds to this. In contrast, the sensor values ​​corresponding to lines LS1, which were also determined for tooth-to-tooth positions of the positive-locking switching element A and F, cannot be clearly assigned to the upper travel range SWO or the lower travel range SWU.

[0109] For this reason, a safety travel range is defined starting from the smallest sensor value LSmin in the direction of the closed operating state of the positive-locking switching element A or F. In this case, the safety travel range consists of a first travel range PTO and a safety range SOFF. The first travel range PTO has a width of such a size that variations in the sensor signal during the determination of the tooth-to-tooth position between the switching element halves 10 do not cause any incorrect assignment or adaptation. These deviations result from both sensor tolerances and so-called gear backlash. The gear backlash causes the positive-locking switching element A or F to...F is adjusted in the axial direction during the operation of the gearbox 3 depending on the load applied to the gearbox 3 relative to the associated sensor as a whole, which prevents a pinpoint determination of the exact position for the tooth-to-tooth position.

[0110] In a first step, the upper limit SWOU of the upper travel range SWO is determined in the Fig. 5a and Fig. The extent shown in 5b is shifted by one adaptation step ADAS towards the lower limit SWOL. This reduces the width of the overlap area between the two travel ranges SWO and SWU. The adaptation step ADAS is an applicable value. The new upper limit SWOUn of the upper travel range SWO lies outside the safety travel range.

[0111] This procedure results in some of the sensor values ​​LS1 now being assigned only to the lower travel range SWU, while the remaining part of the sensor values ​​LS1 is still in the overlap area between the upper travel range SWO and the lower travel range SWU.

[0112] Following this, it is checked whether a further reduction of the upper travel range SWO by the adaptation step ADAS is possible without the new upper limit SWOUn1 being within the safety travel range.

[0113] As in Fig. As shown in Figure 5c, the further reduction of the upper travel range SWO by the adaptation step ADAS would result in the new upper limit SWOUn1 being within the safety travel range.

[0114] Since such an adjustment of the upper travel range SWO would in turn open the possibility that sensor values ​​determined for tooth-to-tooth positions could not be clearly assigned to the upper travel range SWO or the lower travel range SWU, the distance between the new upper limit SWOUn and the safety travel range is determined. Subsequently, the width of the adapted travel range SWO is reduced by only half this distance towards the lower limit SWOL. The upper travel range SWO, shortened in this way, is in Fig. Figure 5d is shown, which is now bounded by the lower boundary SWOL and the new upper boundary SWOUn2.

[0115] The adaptation step of the upper travel range SWO described last results in all sensor values ​​LS1 now being assigned to the lower travel range SWU, while the sensor values ​​LS are still assigned to the upper travel range SWO.

[0116] If further tooth-to-tooth positions are identified, which in turn fall within the overlap area between the adapted upper range of motion SWO according to Fig. If the values ​​in 5d and the lower SWU travel range are located, the procedure described above is repeated. The adjustment of the value in Fig. 5c shown upper travel range SWO in the direction of the in Fig. The movement range SWO shown in 5d is repeated until all sensor values ​​LS1 are assigned to the lower movement range SWU and all sensor values ​​LS are assigned to the upper movement range SWO.

[0117] Fig. 6a again shows a Fig. 5a corresponding representation. The two predefined travel ranges SWO and SWU again represent the starting point for the procedure explained in more detail below. First, the sensor values ​​LS determined for specific tooth-to-tooth positions are all located in the overlap area between the upper travel range SWO and the lower travel range SWU. The sensor values ​​LS1 determined for the tooth-to-tooth positions are all located in the lower travel range SWU.

[0118] In such a scenario, the safety travel range is first defined based on the largest sensor value LS1max. Subsequently, it is checked whether a reduction in the width of the lower travel range SWU, resulting from shifting the lower limit SWUL by the adaptation value ADAS, leads to the new lower limit SWULn lying within the safety travel range. Since this check yields a negative result, the width of the lower travel range SWU is reduced. The new lower travel range SWU is in Fig. 6b shown.

[0119] Since some of the sensor values ​​LS still lie in the overlap area between the upper travel range SWO and the lower travel range SWU, it is checked whether a further reduction of the width of the lower travel range SWU by the adaptation value ADAS is possible. In this case, a further reduction of the width of the lower travel range SWU results in the new lower limit SWUUn1 of the lower travel range SWU lying within the safety travel range. Therefore, a further reduction of the width by the adaptation value ADAS is not carried out.

[0120] The axial distance between the new lower limit SWULn of the lower travel range SWU and the safety travel range is then determined. Following this, the new lower limit SWULn is shifted by half this distance, and the width of the lower travel range SWU is reduced by this value. The lower travel range SWU is now bounded by the again adjusted lower limit SWULn2 and the upper limit SWUU.

[0121] In this case, all sensor values ​​LS are now assigned to the upper travel range SWO and all sensor values ​​LS1 to the lower travel range SWU. Therefore, further adjustment of the travel ranges SWO and SWU will be omitted until sensor values ​​corresponding to tooth-to-tooth positions are again located in the overlap area between the upper travel range SWO and the adjusted lower travel range SWU.

[0122] Fig. 7a again shows a Fig. 5a shows the corresponding representation of the predefined travel ranges SWO and SWU. The determined sensor values ​​LS lie partly only in the upper travel range SWO and partly in the overlap area between the upper travel range SWO and the lower travel range SWU. Simultaneously, the sensor values ​​LS1 are located partly in the lower travel range SWU and partly in the overlap area between the two travel ranges SWO and SWU.

[0123] To assign both the sensor values ​​LS and LS1 solely to the upper travel range SWO and the lower travel range SWU, respectively, it is first checked whether the safety travel range, starting from the minimum sensor value LSmin, is separated from another safety travel range. This additional safety travel range, starting from the maximum sensor value LS1max, extends only across the width of the first travel range PTO in the direction of the upper travel range SWO.

[0124] In this case, this query returns a positive result, and the midpoint between the minimum sensor value LSmin and the maximum sensor value LS1max is determined. Subsequently, the upper limit SWOU of the upper travel range SWO is shifted towards the lower limit SWOL, and the width of the upper travel range SWO is reduced. Similarly, the lower limit SWUL of the lower travel range SWU is shifted towards the upper limit SWOU of the lower travel range SWU, and the width of the lower travel range SWU is reduced. The new upper limit SWOUn of the upper travel range SWO and the new lower limit SWULn of the lower travel range SWU fall within the range specified in the following steps: Fig. The scope shown in 7b is combined.

[0125] The two new limits SWULn and SWOUn are positioned towards the upper limit SWUO of the lower travel range SWU, offset by a safety offset value SOFF1 from the midpoint between the minimum sensor value LSmin and the maximum sensor value LS1max. This easily prevents misinterpretations of further determined tooth-to-tooth positions.

[0126] Fig. Figure 7c shows another scenario where the difference between the minimum sensor value LSmin and the maximum sensor value LS1max is significantly smaller than in the scenario shown in the diagram. Fig. 7a is the basis for this. The distance between the minimum sensor value LSmin and the maximum sensor value LS1max is such that the safety travel range and the further safety travel range overlap. For this reason, the Fig. 7a and Fig. 7b the procedure described in the representation according to Fig. The underlying scenario in section 7c is not applicable in order to correct misattributions of tooth-to-tooth positions of switching element A or F by means of an adaptation according to Fig. 4a to avoid.

[0127] For this reason, the lower limit SWUL of the lower travel range SWU is first raised by a small adaptation step SADAS, and the width of the lower travel range SWU is reduced. The adjusted lower travel range SWU is in Fig. 7d shown.

[0128] Subsequently, a check is performed to see if shifting the upper limit SWOU of the upper travel range SWO by the small adaptation step SADAS towards the lower limit SWOL results in the new upper limit SWOUn lying within the safety travel range. Since this check yields a negative result, the upper limit SWOU is reduced by the small adaptation step SADAS. This adaptation step, in turn, causes all sensor values ​​LS1 to be assigned to the lower travel range SWU. The upper travel range SWO, reduced as described above, is in Fig. 7f shown.

[0129] Following this, the Fig. 6a to Fig. The procedure described in 6d is carried out until all sensor values ​​LS are assigned only to the upper travel range SWO.

[0130] Fig. 8a again shows a Fig. 5a corresponding representation of the predefined path lengths SWO and SWU. In the Fig. In scenario 8a, all determined sensor values ​​LS and LS1 are arranged in the overlap area between the two predefined stroke ranges SWO and SWU. Based on this scenario, the lower limit SWUL of the lower stroke range SWU is determined in the Fig. The circumference shown in Figure 8b is shifted by a further adaptation step ADAS1 towards the upper limit SWUU, thus reducing the width of the lower travel range SWU. This measure means that now some of the sensor values ​​LS are located only in the upper travel range SWO, while the other part of the sensor values ​​LS, like the sensor values ​​LS1, lies in the overlap area.

[0131] Following this, the adaptation will take place in the Fig. The steps described in sections 5a to 5d were carried out further in order to be able to clearly assign the sensor values ​​LS and LS1 to the upper travel range SWO or the lower travel range SWU.

[0132] Based on the previously described adaptation of the tooth-to-tooth area of ​​the switching element 10 according to Fig. 3a or the tooth-on-tooth areas of the positive-locking switching element 10 according to Fig.4a. An overlap ratio between the switching element halves 10 and 11 is determined, starting from the tooth-to-tooth area and moving towards the fully closed operating state of the positive-locking switching element A or F. This knowledge, in turn, makes it possible to apply a torque to the positive-locking switching element A or F as soon as a defined partial overlap ratio exists between the switching element halves 10 and 11, even though the positive-locking switching element is not yet in its fully closed operating state. This is particularly advantageous if the positive-locking switching element A or F cannot be moved from such a partial overlap state to its fully closed operating state within the desired short switching times.

[0133] Up to now, attempts have been made to resolve the issue of a positive-locking switching element sticking in a partially covered operating state by using the aforementioned escalation steps to resolve a tooth-to-tooth misalignment or flank jamming. However, these escalation steps impair switching quality and increase switching time, which is undesirable.

[0134] If a sufficient overlap between the switching element halves 10 and 11 is determined for the transmission of a torque to be applied to the positive-locking switching element, the transmission control unit of the transmission 3 is informed that the positive-locking switching element A or F is in a fully closed operating state. This applies the torque to be transmitted to the positive-locking switching element. Simultaneously, the transmission control unit is informed that the positive-locking switching element A or F is only in a partially overlapped operating state. This information deactivates the adaptation of the end positions of the movable switching element half 10. At the same time, it is checked whether the movable switching element half 10 is being moved towards the closed operating state of the positive-locking switching element A or F and, if applicable, whether it is also moving towards the second end position.

[0135] However, if it is detected that the movable switching element half 10 is being moved towards its first end position, i.e., towards the open operating state of the positive-locking switching element A or F, the torque applied to the positive-locking switching element A or F is reduced. Additionally, the actuating force acting in the closing direction is increased to bring the positive-locking switching element A or F into its fully closed operating state to the required extent. Reference sign 1 Vehicle powertrain 2 Drive machine 3 gearboxes 4 Drive 5 Gearbox input shaft 6 Gearbox output shaft 7 Torsional dampers 8 hydrodynamic torque converters 9 Torque converter lock-up clutch 10, 11 switching element half 10A, 10A1, 10A2 Claw element 11A, 11A1, 11A2 Claw element 10B, 10B1, 10B2 Front surface of the claw element 10C Flank of the claw element 11B, 11B1, 11B2 Front surface of the claw element 11C Flank of the claw element “1” to “9” translation for forward travel “R” translation for reverse A to F Switching element ADAS Adaptation Step ADAS1 further adaptation step LS, LS1 sensor values LS1max maximum sensor value LSmin minimum sensor value P1 to P4 planetary gear set PTO first travel range SADA's small adaptation step SOFF safety area SWO upper parking area SWOL, SWOU limits of the upper travel range SWU lower parking area SWUL, SWUU limits of the lower travel range

Claims

[1] Method for determining an operating state of a positive-locking switching element (A, F) which has two switching element halves (10, 11) that can be positively engaged with each other, wherein at least one of the switching element halves (10) is adjustable between a first end position, which corresponds to an open operating state of the switching element (A, F), and a second end position, which corresponds to a closed operating state of the switching element (A, F), wherein a current position of the switching element half (10) is monitored by means of a sensor, characterized by , that A sufficiently closed operating state of the switching element (A, F) for the transmission of a torque applied to the switching element (A, F) is detected when the sensor signal has a value greater than an applicable value for a defined period of time. which corresponds to a defined overlap between the switching element halves (10, 11), which is smaller than the overlap between the switching element halves (10, 11) when the adjustable switching element half (10) is arranged in its second end position, and if the adjustable switching element half (10) is additionally actuated and adjusted in the direction of the second end position, whereby a tooth-to-tooth position is detected when the sensor determines within an actuation range of the at least one movable switching element half (10) between an open state and a closed state of the switching element (A, F), that the positioning movement of at least one movable switching element half (10) in the closing direction is zero, a ratio between a closing force acting on the switching element (A, F) and a radial force acting on the switching element halves (10, 11), which results from a torque applied to the switching element (A, F), lies within a value range that favors a tooth-to-tooth position and a positioning movement of at least one movable switching element half (10) in the closing direction is detected by the sensor after a reduction of the closing force and / or after an increase in the applied torque. [2] Method according to claim 1, characterized by , that when a movement of the adjustable switching element half (10) in the direction of the first end position is detected, the torque applied to the switching element (A, F) is reduced and the actuating force acting in the closing direction is increased. [3] Method according to claim 1 or 2, characterized by , that the applicable value is varied depending on the torque applied to the switching element (A, F). [4] Method according to any one of claims 1 to 3, characterized by, that the determination of the travel range between the switching element halves (10, 11) is started when The sensor determines a positioning movement of at least one movable switching element half (10) in the closing direction equal to zero and a signal from the sensor within a period of time, which is equal to or longer than a predefined period, greater than or equal to a predefined lower threshold and less than or equal to a predefined upper threshold. [5] Method according to any one of claims 1 to 4, characterized by, that when a tooth-to-tooth position is determined for the first time and the corresponding travel range between the switching element halves (10, 11) is determined, the minimum value of the sensor signal and the maximum value of the sensor signal form limits of the travel range between the switching element halves (10, 11) within which a tooth-to-tooth position is expected. [6] Method according to claim 5, characterized by , that the limits of the actuation range are changed depending on further values ​​of the sensor signal, which are determined during further determinations of the actuation range between the switching element halves (10, 11) for a detected tooth-to-tooth position, if the further values ​​of the sensor signal deviate from the previously determined values ​​of the sensor signal by more than a threshold value. [7] Method according to claim 5 or 6, characterized by, that the limits of the value range are varied depending on the currently determined values ​​of the sensor signal, if a distance between the value range defined by the currently determined values ​​of the sensor signal and the value range that was previously determined is less than or equal to a predefined threshold. [8] Method according to any one of claims 5 to 7, characterized by , that the limits of the previously determined travel range are discarded and the travel range is re-determined when a tooth-on-tooth position is subsequently determined, if the distance between the travel range defined by the currently determined values ​​of the sensor signal and the previously determined travel range is greater than the predefined threshold and the previously determined travel range was set depending on a number of detected tooth-on-tooth positions that is less than a threshold. [9] Method according to any one of claims 5 to 8, characterized by , that the travel range is increased by varying the limits depending on the determined values ​​of the sensor signal until a distance between the limits of the travel range is greater than or equal to a predefined maximum value. [10] Method according to any one of claims 5 to 9, characterized by, that the minimum value of the sensor signal determined for each tooth-to-tooth position and the maximum value of the sensor signal also determined are each compared to the limits of a travel range which has already been determined depending on a number of determined tooth-to-tooth positions greater than a threshold value, wherein the limits of the travel range are increased or decreased by an offset if the determined minimum value and the determined maximum value of the sensor signal each deviate from the lower limit or from the upper limit of the travel range by values ​​greater than an amount of a threshold value. [11] Method according to claim 10, characterized by, that the limits of the travel range are varied depending on the minimum value of the sensor signal determined for a tooth-to-tooth position or the maximum value of the sensor signal also determined, if the distance between the limits of the travel range has already reached or exceeded the maximum value and the minimum value or the maximum value of the sensor signal lies outside the travel range, wherein the limits of the travel range are then adjusted to each other in such a way that the distance between the limits of the adjusted travel range does not substantially exceed the maximum distance. [12] Method according to any one of claims 1 to 11, characterized by, that starting from two predefined actuation ranges (SWO, SWU) between the overlapping switching element halves (10, 11), two actuation ranges are determined if each of the switching element halves (10, 11) is formed with two groups of claw elements (10A1, 10A2, 11A1, 11A2), wherein the claw elements (10A1, 11A1) of the first group have a greater length in the actuation direction of the at least one movable switching element half (10) than the claw elements (10A2, 11A2) of the second group and the claw elements (10A1, 10A2, 11A1, 11A2) of the two groups are arranged alternately next to each other in the circumferential direction of the switching element halves (10, 11). [13] Method according to claim 12, characterized by, that the limits (SWOU, SWUL) of the travel ranges (SWO, SWU) are adjusted until all values ​​of the sensor signal determined for tooth-to-tooth positions and which lie within the overlap range of the two travel ranges (SWO, SWU) are assigned to only one of the two travel ranges (SWO or SWU). [14] Method according to claim 12 or 13, characterized by , that the travel range (SWO), which represents a range of values ​​for signals from the sensor determined for tooth-to-tooth positions between the claw elements (10A1, 11A1) of the first groups of the switching element halves (10, 11), has such a minimum width that the distances between the minimum and maximum values ​​of the sensor signal determined for each tooth-to-tooth position resulting from movements of the switching element (A, F) relative to the sensor and from tolerance-related sensor behavior are included by the travel range (SWO). [15] Control unit for determining an operating state of a positive-locking switching element (A, F) which has two switching element halves (10, 11) that can be positively engaged with each other, wherein at least one of the switching element halves (10) is adjustable between a first end position, which corresponds to the closed operating state of the switching element (A, F), and a second end position, which corresponds to an open operating state of the switching element (A, F), wherein a current position of the switching element half (10) is monitored by means of a sensor, characterized by , that the control unit is designed in such a way that a sufficiently closed operating state of the switching element (A, F) is detected for the transmission of a torque applied to the switching element (A, F), if the sensor signal has a value greater than an applicable value over a defined period of time, which corresponds to a defined overlap between the switching element halves (10, 11), which is smaller than the overlap between the switching element halves (10, 11) when the adjustable switching element half (10) is arranged in its first end position, and if the adjustable switching element half (10) is additionally actuated and adjusted in the direction of the first end position, whereby a tooth-to-tooth position is detected when the sensor determines within an actuation range of the at least one movable switching element half (10) between an open state and a closed state of the switching element (A, F), that the positioning movement of at least one movable switching element half (10) in the closing direction is zero, a ratio between a closing force acting on the switching element (A, F) and a radial force acting on the switching element halves (10, 11), which results from a torque applied to the switching element (A, F), lies within a value range that favors a tooth-to-tooth position and a positioning movement of at least one movable switching element half (10) in the closing direction is detected by the sensor after a reduction of the closing force and / or after an increase in the applied torque. [16] Control unit according to claim 15, characterized by that the same executes the method according to one of claims 1 to 14 on the control side. [17] Computer program product comprising program code means stored on a computer-readable data carrier to perform all steps of a method according to any one of claims 1 to 14 when the computer program product is executed on a computer or on a corresponding computing unit.

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