Change gear with electric motor-driven shift drum and method for controlling such a change gear

Description

[0001] The present invention relates to a method for controlling a torque- and / or speed-converting variable-speed transmission. The invention also relates to such a torque- and / or speed-converting variable-speed transmission.

[0002] In conventional vehicle drives, the drive power of an internal combustion engine is transferred mechanically to at least one driven axle of the vehicle. Since the typical speed ranges in which internal combustion engines operate economically and with sufficient torque and power do not match the rotational speeds required by the axle drive, intermediate transmission units are necessary that function as both torque converters and speed converters.

[0003] Such transmissions can be designed as manually shiftable gearboxes, in which gear ratio changes are performed while simultaneously disengaging a power transmission, which can usually be achieved with a friction clutch that can be actuated by the driver as needed. In addition to so-called automatic transmissions, which can be designed as planetary gears, for example, there are numerous other transmission types in which gear ratio changes are performed manually.

[0004] Torque- or speed-converting variable-speed transmissions can also be used in electric vehicle drives, since the electric drive motors used as traction drives typically cannot cover the entire speed range equally effectively. Depending on the drive concept, a high starting torque cannot usually be combined with a high top speed, so it may be useful to be able to achieve this using a variable-speed transmission integrated into the drivetrain.

[0005] Manually shiftable gearboxes often have gear sets whose engagement can be controlled by sliding sleeves that can be moved on shafts mounted in the gearbox housing, in order to bring different gear pairs into meshing engagement. The sliding sleeves, which are mounted on the shafts and can be moved there, are often actuated by means of rotatable shift drums, whereby the shift drums interact with shift forks or shift pins via control cams, which in turn engage with the sliding sleeves or interact with the sliding sleeves. A rotation of the shift drum by a defined angle of rotation, which can be less than 90°, for example, causes a displacement or angular adjustment of the shift forks or shift pins coupled to the sliding sleeves, which in turn activates or deactivates one of the gear pairs and thus engages or disengages a gear stage of the gearbox.

[0006] A particularly compact design of such manually operated change gears is a so-called sequentially operating gearbox, in which partially or fully automatic gear shifting and gear ratio changing processes are also possible through the use of suitable sensors and suitable actuators.

[0007] DE 10 2010 013 962 A1 describes a sequential transmission shifting system with a control for a motor-driven transmission shift drum. The transmission comprises at least two gear sets that can be selectively coupled, as well as a rotatable shift drum for selecting the gear sets to be engaged, whereby an input shaft of the transmission is connected to an output shaft of the transmission in a force-locking and torque-locking manner. The shift drum is driven by a control motor. A torque sensor detects a drive torque exerted by the control motor on the shift drum. The control motor is controlled based on the torque values ​​detected by the torque sensor. The coupling of the transmission set is controlled in this way.

[0008] A control system with an actuator for changing the position of a shift drum of a gear change transmission is also known from WO 2004 / 65825 A1. A position controller ensures that the position of the shift drum is controlled when changing from an original gear to a target gear.

[0009] Furthermore, EP 1 199 500 B1 describes an electric motor-driven shift drum of a change-speed gearbox, wherein the electric motor driving the shift drum has a housing-less stator and a rotor which, in the interest of a compact design, are arranged between the shift drum and an axle supporting the latter.

[0010] A dog clutch transmission system is also known from DE 10 2012 200 183 A1. The dog clutch transmission system with dog clutches is intended to reduce the noise resulting from the engagement of dogs during the meshing of gears. To this end, the dog clutch transmission system comprises a plurality of gears installed adjacent to one another on the corresponding, identical shafts such that they are not rotatable relative to the associated shafts and are axially displaceable. Furthermore, further gears are provided, which are installed such that they are rotatable relative to the associated shafts and are not axially displaceable. Each of the plurality of gears has dog teeth that protrude in the axial direction, and each of the further gears has dog holes recessed in the axial direction. Gear stages can be shifted by engaging and disengaging the dog teeth and the dog holes.A speed change ratio measure of a speed change ratio at any n-speed gear stage to a speed change ratio at an (n + 1)-speed gear stage is set to 0.725 or more.

[0011] Known sequentially shifting transmissions can be designed as so-called dog boxes, the characteristics of which include the fact that they can be shifted very quickly and without the synchronization known from conventional change gears. Such a so-called dog box, which is also referred to as a dog ring transmission, can in principle also work according to a familiar H-shift pattern. The shift sleeves used in such dog ring transmissions or dog boxes do not have the usual large number of small meshing teeth for axial engagement with the gear wheels to be shifted, but usually only a few large teeth, which are also slightly undercut. The same number of teeth can be found on the front sides of the gear wheels that can be brought into engagement with the sliding sleeves. The shift sleeves and gear wheels can, for example,have four to six large teeth, whereby the ratio between tooth and free space above the front engagement ring of the shift sleeves and gear wheels can be around 30:70, which is intended in particular to reduce the risk of tooth hitting tooth during the gear shifting process.

[0012] Since the conventional bronze synchronizer rings are omitted, such transmission designs feature sudden synchronization when the teeth mesh. The teeth are flat rather than conical and are relief-ground or undercut on the sides, which can cause the gear wheel and shift sleeve to contract under load and, at the same time, prevent the gears from jumping out again once the connection has been established. However, this very harsh synchronization leads to relatively high wear on the tooth edges of the shift sleeves. In order not to place additional strain on the teeth and tooth edges, gear shifts must be rapid, usually significantly faster than with conventionally synchronized transmissions. However, gear shifts can optionally be performed without the aid of the clutch, provided the load in the drivetrain is sufficiently reduced at the right time.

[0013] A dog-box transmission can be designed as a sequential transmission using a shift drum. The term "sequential transmission" refers to the sequence of gear steps, not the arrangement of the gears within the transmission. The shift drum, which is responsible for moving the sliding sleeves and is tailored to the specific transmission, has milled grooves that serve as guides for pushing the shift forks into position. Selecting the gate and engaging the gear occur largely simultaneously. The shift drum is tailored to each transmission. One advantage of such transmissions is their high shifting speed.

[0014] The primary object of the invention is to provide an improved method for controlling a change-speed gearbox with an electric motor-driven shift drum, whereby all typically occurring operating states, which include in particular all changeover processes for selecting different gear ratios of the gearbox, can be carried out as reliably and as gently as possible.

[0015] Related to this is the further object of the invention to provide an improved controllable change gear transmission with an electric motor-driven shift drum, with which the typically occurring operating states, which include in particular all change processes for selecting different gear ratios of the transmission, can be carried out as reliably and as gently as possible on the material.

[0016] These objects are achieved by a method for controlling a change-speed transmission having the features of independent method claim 1 and by a change-speed transmission having the features of independent claim 25. Further advantageous embodiments are described by the respective dependent claims.

[0017] To achieve the stated objects, the present invention proposes a method for controlling a torque- and / or speed-converting variable-speed transmission having an input shaft and an output shaft as well as at least two gear ratios. The variable-speed transmission controlled by the method according to the invention further comprises at least two interchangeable gear pairs. The gears of these at least two interchangeable gear pairs are each mounted on shafts and / or rotate on or with these shafts in a transmission housing or on shafts mounted in another way. Typically, these gears or gear pairs can be activated or engaged by displacing claw rings in the axial direction on the shafts in order to be able to bring different gear pairs into meshing engagement depending on the desired gear ratio.

[0018] Furthermore, the change gear comprises suitable shifting elements, in particular in the form of movable shift forks, shift pins or the like, which act on sliding sleeves which are connected to the gear pairs or the gears of the gear pairs and can change them, which means in particular an axial displacement of the claw rings which can be brought into engagement with the gears, the claw rings ensuring that the respective gears or gear pairs come into engagement, which deliver the respective gear ratio to be selected.

[0019] In addition, the shift elements are engaged and / or operatively connected to a shift drum that can be brought into defined angular positions and rotated between these angular positions. This shift drum has an electric motor drive in the form of a direct electric motor drive that can rotate the shift drum and bring it into the respective defined angular positions. Preferably, the direct electric motor drive of the shift drum can be formed by a brushless DC motor or another suitable electric motor that has the desired properties that are necessary or particularly desirable for the intended application.

[0020] Such a drive motor, which due to its specific application belongs to the so-called slow-speed motor category, can also be referred to as a torque motor. Such torque motors exhibit relatively high torques at comparatively low speeds. This allows the electric motor-based shift drum drive in such a change-speed transmission to be designed particularly compactly and with a high power density.

[0021] A useful embodiment of the change gear controllable according to the invention can provide that the electric motor direct drive coupled to the shift drum is modularly pluggable and / or quickly interchangeable and / or replaceable without tools.

[0022] The brushless motor enables high power density and thus a particularly compact design, eliminating the need for any gear ratios between the shift drum and the motor. Furthermore, such a compact motor with high power density offers numerous advantages in terms of packaging, as it allows for a high degree of variability in the installation of the motor, optionally within the transmission housing, eliminating the need for a shaft feedthrough for driving the shift drum.

[0023] Furthermore, since such brushless motors can be controlled very precisely and can be used as stepper motors, a sensor system for detecting the current rotation angle of the shift drum can be dispensed with if necessary. Furthermore, the change-speed transmission according to the invention can be operated without a so-called gear position sensor, since such a sensor is either already present in the electric drive motor for the shift drum or can be substituted due to its specific properties.

[0024] Optionally, the electric motor direct drive of the shift drum in the change-speed gearbox can be provided by a so-called internal rotor motor. In this case, the rotor is located inside, while the stator surrounding the rotor is arranged outside. A sensible design of such an internal rotor motor, which can particularly be formed by a torque motor, can, for example, be equipped with fewer slots than poles, which can reduce undesirable detent effects. A variant with, for example, twelve slots and fourteen poles can fulfill this purpose of very slight detent.

[0025] Alternatively, the electric motor-driven direct drive of the shift drum can also be implemented using a so-called external rotor motor. In this case, the stator is located inside, while the rotor surrounding the stator is arranged outside. A sensible design for such an external rotor motor, which can particularly be implemented using a torque motor, can, for example, be equipped with fewer slots than poles, which can reduce undesirable detent effects. A variant with, for example, twelve slots and fourteen poles can fulfill this purpose of very slight detent.

[0026] Furthermore, it may be advantageous to provide neutral positions between the gears in a variant of the change gear, which can be achieved in particular by the electric motor direct drive of the shift drum providing or being able to provide neutral positions between two adjacent gear stages, in particular by its controllability.

[0027] In connection with the control method according to the invention for the previously described change-speed transmission, explained below in numerous embodiments, it is particularly useful to electronically control the electric motor direct drive of the shift drum, which can be done, for example, via a bus system such as a CAN bus or similar system. In addition to precise controllability, such control has the further advantage that the control electronics can influence or define the behavior of the electric motor.

[0028] For example, the drive torque of the motor can be limited by means of a current limiter or specified within desired limits. Furthermore, by precisely recording the current current consumption of the drive motor for the shift drum, the entire behavior of the components operatively engaged with the shift drum and / or actuated by the shift drum can be derived and recorded. These components operatively engaged with the shift drum and / or actuated by the shift drum include the shift elements or shift forks, the sliding sleeves moved by the shift elements or shift forks on the transmission shafts, which in turn can be brought into engagement with the adjacent gears of the gear pairs through the action of the shift elements or shift forks actuated by the shift drum, thereby selecting a desired gear ratio of the transmission.

[0029] As already mentioned, the present invention proposes a method for controlling a torque- and / or speed-converting variable-speed transmission, as previously explained in various embodiments, and by which the above-stated object is to be achieved. The variable-speed transmission controllable by means of the method according to the invention has an input shaft and an output shaft as well as at least two gear ratios, each of which is assigned at least one interchangeable gear pair. Furthermore, the transmission is characterized in that shifting elements act on sliding sleeves, which are connected to the gear pairs or the gears of the gear pairs and / or can be brought into operative engagement and can interchange them.In addition, the shift elements are in engagement with a shift drum that can be brought into defined angular positions and rotated between these angular positions, this shift drum being coupled to an electric motor direct drive that rotates the shift drum to change gear ratios and brings it into the respective defined angular positions.

[0030] A permanent magnet synchronous motor can be used as the direct electric motor drive for the shift drum, since this type of motor is particularly suitable for the application described here.

[0031] When activating or deactivating a gear ratio and / or changing gear ratios of the gearbox, the moments of inertia of the actuator, the shift drum, and the shift fork(s) to be moved are taken into account and incorporated into the control cycle. For this purpose, the rotational energy and its partial temporal derivative are calculated, taking into account the movement of the shift drum. This applies, for example, when the sliding sleeve is disengaged from a gear of the gear pair of a first gear ratio, in which at least one sliding sleeve is axially displaced and disengaged from the gear of the gear pair of the first gear ratio.This also applies when establishing an engagement of the sliding sleeve with a gear of the gear pair of a second transmission stage, in which the sliding sleeve is also axially displaced and brought into engagement with the gear of the gear pair of the second transmission stage.

[0032] Using the method according to the invention, very precise and reliably reproducible gearshift operations can be performed in a sequential transmission with an electromagnetic drive motor that serves as an actuator for the shift drum. Furthermore, the method according to the invention is particularly suitable for performing gearshift operations with comparatively low mechanical loads and thus with little or reduced wear, since shock loads and pronounced impulse loads, in particular, can be reduced.

[0033] The term “gear shifting operations” used here refers to all different upshifts and downshifts into different or consecutive gear ratios that can be carried out with the respective transmission.

[0034] In order to enable a smooth gearshift process and to avoid faulty processes during gearshifts and the resulting or associated damage to the mechanics, in addition to other optional functionalities that are explained further below, at least the rotational energies of the rotating parts involved in the gearshift processes are taken into account. The rotational energies of the rotating parts can be determined for each existing transmission by knowing the masses and moments of inertia of the rotating parts, so that parts that are in gear engagement and / or are connected in a rotationally fixed manner are also known as a complete rotating body in terms of their masses and moments of inertia. In addition, all speeds within the transmission can be permanently determined and / or derived, for example based on the influences of the shift drum, in particular the electric motor-operated shift drum (so-calledE-shift drum), through the shift forks etc.

[0035] To carry out the switching sequences, it is advisable to use electronic switching programs for the shift drum that are able to take into account a wide variety of boundary conditions and / or to use different characteristic maps.

[0036] For all gearshifts in a sequential transmission, especially in a so-called dog-ring transmission, it is necessary to reduce as much as possible any overshoot and / or undershoot of the actual position during adjustment of the target position and thus the target gear. These conditions pose the risk of the target gear, often referred to as the second gear ratio in this context, being disengaged again. This can result in damage to the mechanism, particularly to the affected shift sleeve and / or the dog ring engaged or affected by it. Furthermore, premature braking of the gear pair of the target ratio, depending on the control difference of the positions, is also not advisable, as this can lead to damage during gear engagement and can also result in a significant loss of gearshift performance.

[0037] As already explained above, the dog rings of sequential gearboxes have a comparatively small number of teeth, which also have undercuts, so that a comparatively hard engagement between the corresponding teeth of the shift sleeves and the adjacent frontal dog rings of the gears of the various gear ratios occurs and must occur for a successful shifting process.

[0038] Using sufficiently fast operating control and regulating devices, the method according to the invention calculates at all times the rotational energy that is present both in the actuator, i.e. in the shift drum and in its drive motor, as well as in the moving and rotating parts of the transmission, whereby an algorithm can be used to determine an approximately ideal deceleration and an ideal braking point for each gear to be shifted, since the control program can predict or at least estimate the future position of the tooth flanks and engagement points of the dog rings based on the respective existing and / or expected rotational energy.

[0039] Depending on the design of the electric motor used for the shift drum drive, a field-oriented control, also known as vector control, can be incorporated into the control algorithm for targeted control of the rotational energy and the torque provided by the electric drive. By selectively superimposing the field-oriented control with so-called space vector modulation, improved and, ideally, optimal power efficiency can be achieved. The process, only outlined here, serves to optimize torque production or torque transmission as well as effective reactive power compensation.

[0040] Factors can be set using various tables to select and apply the braking algorithm for the respective application. As soon as the braking algorithm of the system according to the invention is activated, it calculates an additional vector, which is added to the field vector of the standard controller. Thus, the system serves as an amplifier for the actual control cycle.

[0041] Optionally, the method according to the invention can take into account the rotational energies of the rotating parts meshing with the respective gears involved in changing a respective gear ratio. As already explained above, this option is useful because otherwise the cumulative rotational energies of several meshing rotating bodies might be disregarded.

[0042] In addition, the rotational energies for different gear ratios can be weighted differently and / or taken from tables or maps and considered differently for each gear. This makes it possible to adjust the parameters used separately for each gear change, since the moments of inertia between different gear pairs are generally different, which also results in different rotational energies.

[0043] A useful variant of the method according to the invention can provide that the rotational energies of the shift drum and / or the electric motor direct drive driving the shift drum are taken into account additionally or separately.

[0044] In order to be able to carry out the process effectively, it will generally be necessary to electronically couple the electric motor direct drive of the shift drum with a drive control of a drive motor so that the torque requirements required for changing operations can be carried out in a coordinated manner by the drive motor, in particular in connection with the necessary fast and often clutchless switching operations.

[0045] According to a further embodiment, the method can provide that during and / or in preparation for a disengagement process of a sliding sleeve from a gearwheel of a first gear stage to be deactivated, also referred to as the initial gear, a drive torque of the drive motor is reduced. This serves, in particular, to enable the sliding sleeve to be disengaged with a reduced disengagement force, i.e., the drive is preferably largely load-free during these periods.

[0046] During the disengagement process, it may be useful to preload the shift fork, which is operatively engaged with the sliding sleeve, with a defined and / or variable preload force. This means that it can be continuously preloaded with a defined gradient. The preload force is lower than the shift force that is only exerted on the shift fork when the drivetrain is unloaded. This can suppress the spring effect resulting from the elasticity of the shift fork. Ideally, an elastically preloaded shift fork, which behaves like a spring, can effectively prevent the sliding sleeve from bouncing back.

[0047] After a valid shift request, which has been checked for plausibility and feasibility by the control system, the first action the actuator must perform is disengage the initial gear. To do this, the control system requests a so-called cut from the engine control unit of the drive motor coupled to the gearbox. This functionality renders the drive train largely torque-free by having the drive motor reduce the driving torque or completely downgrade it to a value of zero. This step is necessary to separate the dogs or shift sleeves from the gear wheel and to disengage a gear without clutch operation.

[0048] Depending on the quality of the motor control, the drive motor, and the operating point set, a period of time passes until the motor can reduce the torque to the required extent and the system is free of load. Often, however, the gearshift is already activated during this period, and the shift actuator attempts to disengage the gear that is still subject to torque. This leads to the shift fork of the gear pair being preloaded, as the shift actuator also builds up a force to disengage the gear. If the drive gear then becomes torque-free, the shift fork can behave like a spring component and jump back completely into the initial gear. This leads to a loss in shifting performance and can cause mechanical damage.

[0049] The above-mentioned process variant prevents such behavior by increasing the torque applied by the shift actuator to the shift fork at a defined gradient when the drivetrain is not yet torque-free and maintaining it at a defined level so that not all of the actuator's force is transferred to the shift fork. This prevents the spring action of the shift fork from taking effect, and the gear can be disengaged without rebound when the system is torque-free. Once the gear has been successfully disengaged, this process mode is terminated, and the system can return to the normal shift sequence.

[0050] Furthermore, the method can provide for the disengagement process to occur after a shift request with a defined delay and in coordination with the behavior of the drive motor, whose drive torque has previously been reduced. This can preferably achieve improved coordination with the typical deceleration process of the respective drive motor, since premature activation only leads to an otherwise ineffective preloading of the shift fork, which would, however, lead to undesirable power consumption of the shift drive for the shift drum and its unnecessary heating.

[0051] When we talk about a so-called deceleration process, we mean speed reductions that occur after a reduction in the power or speed requirement. This drop in engine speed does not occur suddenly after a power or speed requirement has been reduced, as numerous moments of inertia of the rotating parts ensure a gradual decrease in engine speed. The lower the total effective flywheel masses, the faster an engine can decelerate once its speed or power requirement has been reduced.

[0052] Conversely, essentially the same principles apply, meaning that an increase in engine speed can only occur with a certain delay due to the effective inertia forces. To reduce this inertia, it is common practice in motorsports to lighten relatively heavy rotating parts such as a clutch flywheel connected to the crankshaft of an internal combustion engine. This can both reduce the deceleration time and significantly accelerate a sudden increase in engine speed.

[0053] When a gear shift is initiated, the shift drum receives a corresponding request so that the shift drum, acting as an actuator, can begin the disengagement process for the initial gear. Regardless of whether this is performed with the gradual preload of the shift fork described above or without such preload, it may happen that the drivetrain is not yet free of load, for example, because the combustion engine or electric motor used to drive the vehicle still requires a defined period of time before the operating point for torque-free behavior of the drivetrain can be adjusted.

[0054] Depending on the application and design of the combustion engine or electric motor used as the drive motor for a vehicle, this time period may be several milliseconds, during which a disengagement process is impossible and the actuator performs unnecessary work. The actuator's electric motor, i.e., the drive motor for the shift drum, uses a defined power consumption.

[0055] Since the effects of a switching operation that cannot be carried out due to excessive preload in the moving parts should be reduced or completely avoided if possible, the present method offers the option of specifying a time period for each defined switching operation, which the actuator waits before disengaging after the switching request has been received. This option makes it possible to significantly reduce the average power consumption and the associated heating of the actuator.

[0056] Furthermore, according to a further embodiment, the method can provide that, in preparation for or during an engagement process, the sliding sleeve, previously disengaged from the gear of the deactivated first gear stage, is searched for a positive fit as it approaches an adjacent gear of a second gear stage to be activated. This is done by detecting a torque and / or speed curve of the electric motor direct drive of the shift drum and determining from this whether the sliding sleeve has engaged the gear of the second gear stage to be activated. In this case, when a dog ring or a sliding sleeve is moved toward a gear of a target gear, an attempt is made to find the appropriate "gap" in order to mesh the dog rings.At the same time, by recording the speed curve and the current consumption in the drive motor for the shift drum, it can be determined whether the dog "engages" and engages or "jumps back", which is transmitted as an impulse via the shift fork and introduced into the shift drum.

[0057] During each gear shift, there is a certain probability of hitting a so-called dog of the target gear. The dogs of the target gear, which correspond to the dogs of the shift sleeve, are mounted on the gear ring of the target gear and are thus part of the rotating components of the transmission. Several dogs are attached to a transmission gear at an angular distance to shorten the distance. The distance between two dogs that span a common angle is called the dog window.

[0058] The dog on the shift sleeve, which is moved into the target gear with the shift fork, is mechanically separated from the gear dog rings and must be transported into a dog window of the target gear in order to engage a gear. If the dog of the shift sleeve encounters a dog of the target gear during the engagement phase, an impulse is converted, which leads to energy being transferred to the shift fork. Depending on the energy input, the translational vector of the shift fork can be inverted and the target gear is disengaged back towards the initial gear. This process can also be viewed as a dog-to-dog event and will be referred to as such in the present context.

[0059] It has been proven that these faulty meshing processes, known as dog-to-dog events, can occur relatively frequently during any gearshift. Since these events lead to pronounced discontinuities in the control sequences, it is useful to detect such dog-to-dog events in order to initiate appropriate countermeasures.

[0060] For this purpose, the method according to the invention provides a specific algorithm that acts in parallel as a sub-element of the actual shifting sequence and detects such a dog-to-dog event based on the speed and direction of movement of the actuator or the shift element actuated by the shift drum, or the shift fork moved by the shift drum. This detection can possibly be achieved indirectly by analyzing the current consumption and the speed curve of the shift drum drive, since the specific characteristics of such dog-to-dog events can be determined quite precisely and are thus also detectable in the normal shifting sequence.

[0061] A further advantageous method option can provide that, after the occurrence of a dog-to-dog event and thus an unsuccessful engagement process and / or after an unsuccessful attempt to establish engagement between the sliding sleeve and the gearwheel of the second gear ratio to be activated, the engagement process is repeated at least once, preferably several times, by correspondingly reversing and rotating the shift drum again with the shift fork guided accordingly. In the control program, this method variant can also be characterized by initiating a repetition of the shifting process sequences after detecting an inversion of the translational vector of the shift fork and the concomitant disengagement of the dog from the target gear back toward the initial gear.

[0062] How often such faulty switching operations are sensibly repeated depends on the respective programming and also on the switching philosophy represented in the program. A certain number of permitted repetitions can certainly be useful in order to keep the circuit functional under as many external conditions as possible. However, an excessive number of permitted repetitions can also lead to damage if, for example, other faulty phenomena are skipped or ignored.

[0063] Optionally, the method can also provide that an unsuccessful engagement process and / or an unsuccessful attempt to establish engagement between the sliding sleeve and the gear of the second gear ratio to be activated leads to further analysis processes. For example, a dog-to-dog event and an unsuccessful engagement process can be detected and / or recognized at least based on the detection of the rotational speed of the gear or gears of the second gear ratio and / or based on the detection of the rotational speed and / or the rotational angle of the selector shaft and / or the drive torque of the electric motor direct drive required to rotate the selector shaft.

[0064] It is useful to perform such dog-to-dog detection based on the speeds of the gears, the selector shaft, and the drive torque for rotating the selector shaft. This check determines whether the direction of rotation reverses during movement within a certain angle window of the actuator, or whether the speed gradient exhibits a significant discontinuity. If this is the case, the algorithm sends a message to all other software components indicating that a switching process should be restarted and repeated.

[0065] In principle, it is advisable to interrupt the shifting process early upon detection of a dog-to-dog event and to reverse the previously inverted "back" shifting movement of the shift fork as quickly as possible in order to attempt another shift. In this way, part of the expended actuating energy, which was transmitted by the impulse, can be converted to direct the movement vector of the shift fork and the sliding sleeve moved by it back toward the target gear. These detection steps may be repeated several times, although identical repetition processes do not always have to follow one another, as the shifting processes may have been aborted at different times. However, essentially the same measures are repeated when the target gear is to be engaged again.

[0066] Furthermore, in the method according to the invention, it can be provided that in connection with an incomplete engagement process and any resulting jamming and / or hooking of the sliding sleeve with the gearwheel of the second gear ratio stage, at least the speed of movement and the course of movement of the shift fork and / or the shift drum controlling it are recorded and analyzed.

[0067] If, in connection with a dog-to-dog event, an interference connection or press fit occurs at dog edges because the shift fork continues to press without the dog actually being engaged, this can be detected by recording the speeds and movement patterns of the shift element or the shift fork or the associated shift drum, and appropriate countermeasures can be initiated. Since such an interference connection cannot be reliably resolved by the shifting sequence and handling of dog-to-dog events described above, further detection and remedial steps may be necessary.

[0068] To detect such a specific dog-to-dog event, which can be characterized in particular by a mechanical interference fit, at least two, but ideally a total of three, conditions are checked. First, it is checked whether a dog-to-dog event has occurred. It can also be checked and detected whether the shift element or shift fork was moved more slowly than would normally be expected. As a third criterion, it can be recorded whether the excessively low speed of the shift drum activated for moving the shift element or shift fork remains at this low level over a certain period of time.

[0069] In order to counter such an event, two different strategies have been developed, which are explained in more detail below.

[0070] As an option for counteracting such a specific dog-to-dog event, which can also be considered a "long" dog-to-dog event, the method offers the possibility of reducing and / or oscillating the actuating force and / or rotational speed of the shift drum at least once or several times in connection with an incomplete engagement process and the associated jamming and / or interlocking of the sliding sleeve with the gear of the second gear stage. To resolve such a so-called "long" dog-to-dog event, the actuator or the shift drum can reduce its actuating force exerted on the shift fork at short intervals, which may potentially disengage the mechanical coupling.

[0071] As a further option for counteracting such a specific dog-to-dog event, which can also be considered a "long" dog-to-dog event, the method offers the possibility of reducing and / or inverting the rotational speed of the shift drum once or several times in connection with an incomplete engagement process and the associated jamming and / or interlocking of the sliding sleeve with the gear of the second gear stage. To resolve such a "long" dog-to-dog event, it may be useful to actively move the shift fork away from the dog of the target gear and back toward the initial gear to actively force a separation of the mechanical coupling and then initiate a new engagement process.

[0072] Preferably, however, the actuator does not move very far back, but only a small distance away from the target gear, at least far enough to ensure that the dog ring, which can be moved with the shift fork, is separated from the dog of the target gear in order to then begin a new engagement process.

[0073] Another undesirable event, which can be seen in connection with the numerous variations of the dog-to-dog events described above, can be referred to and viewed as "bouncing." This is a specific dog-to-dog event in which the dog ring, after almost completing the shift, rebounds sufficiently to engage the initial gear.

[0074] Thus, in a useful process variant, it can be determined whether, in connection with a nearly complete or complete engagement process and the associated fit of the sliding sleeve with the gear of the second gear stage, an unexpected return movement of the sliding sleeve from the fit with the gear of the second gear stage into the gear of the disengaged first gear stage occurs. To verify whether this is the case, i.e., whether so-called "bouncing" occurs, at least the movement speed and movement pattern of the shift fork and / or the shift drum controlling it are recorded and analyzed.

[0075] It should be emphasized that such a priority, in which the rebounding shift fork has stored so much energy that the initial gear is engaged again, should be avoided because of the comparatively high risk of damage.

[0076] In connection with a "bouncing"—a specific dog-to-dog event—a useful process variant can also detect and verify whether, in connection with an incomplete engagement process and the resulting jamming and / or interlocking of the sliding sleeve with the gear of the second gear stage, the sliding sleeve has moved backward from its fit with the gear of the second gear stage into the gear of the disengaged first gear stage. If this is the case, at least the movement speed and movement pattern of the shift fork and / or the shift drum controlling it are recorded and analyzed.

[0077] To reliably detect such "bouncing," a separate algorithm monitors each dog-to-dog event for its impulse transmission and the distance traveled by the shift fork, thus detecting the risk of bouncing. To prevent damage to the transmission, the system reacts relatively quickly when a potential bouncing is detected, mitigating the occurring impulses in a timely manner. This generally prevents the damaging feedback to the initial gear.

[0078] In addition to the diverse phenomena that occur when changing gear ratios, as explained above, in certain, albeit rare, situations, overshoot can occur when adjusting the target position. Such an overshoot process is very similar in its characteristic accompanying phenomena to the previously discussed "bouncing." If, for example, a stronger impulse is applied to the shift fork due to an occurring and detected dog-to-dog event, overshoot can subsequently occur, which can lead to an unintentional re-disengagement of the dog-ring connection. This results in a faulty shifting process, often referred to as a "misshift."

[0079] Thus, a further method variant can provide that in connection with an incomplete engagement process and the associated jamming and / or hooking of the sliding sleeve with the gear of the second gear stage and after a return movement of the sliding sleeve out of the fit with the gear of the second gear stage without establishing an engagement with the gear of the disengaged first gear stage, at least the movement speed and the movement course of the shift fork and / or the shift drum controlling it are recorded and analyzed.

[0080] Optionally, a slightly modified method variant can provide that in connection with an almost complete or complete engagement process and the associated fit of the sliding sleeve with the gear of the second gear stage and after a return movement of the sliding sleeve from the fit with the gear of the second gear stage without establishing an engagement with the gear of the disengaged first gear stage, at least the movement speed and the movement course of the shift fork and / or the shift drum controlling it are recorded and analyzed.

[0081] Once overshoot is detected, appropriate countermeasures can be taken. In conjunction with appropriate countermeasures, the positions of the shift fork and / or the sliding sleeve moved by it are continuously monitored when engaging the target gear, allowing timely intervention as soon as the detected actual position deviates too far from a target position, specifically in typical areas where overshoot can occur or has occurred. If deviations between the actual and target positions are detected that exceed a limit value, the appropriate target position can be actively controlled. This can be achieved with the help of a suitable control vector, which ensures that the target position is reached again very quickly and with high performance, before an unintentional disengagement of the dog ring connection can occur.

[0082] Optionally, after a detected backward movement of the sliding sleeve out of the fit with the gear of the second gear stage, an amplified and / or extended and / or at least partially or sectionally repeated switching pulse for the movement of the shift fork can be initiated by the electric motor direct drive for the shift drum.

[0083] Likewise, in rare cases, an applied actuating pulse and / or a movement pulse of the actuating elements involved in the shifting process may be too small to achieve the desired target gear, which can be considered an undershoot. Such an actuating pulse may essentially depend on the moving parts in the transmission that are involved in translational movements associated with actuating and / or gear-changing processes.

[0084] Both overshoot and undershoot should be avoided, and appropriate remedies should be found for each. Such undershoot can be considered a "creep" of the shift sleeve or the shift fork that shifts it into the target gear.

[0085] A corresponding method variant can provide for detecting and evaluating the rotational energy stored in the gear pairs and / or in the shift drum to detect a shift speed of the sliding sleeve below a defined minimum shift speed and increase the rotational speed of the gear pair of the second gear ratio to be engaged. To remedy this, a vector difference is added to the actuating movement of the shift fork or the sliding sleeve, which can be referred to as undershoot handling.

[0086] In addition, undershoot can also be counteracted by accelerating the gears to generate the necessary rotational energy to engage the target gear with the desired momentum. This is useful because it allows the engagement process to be terminated before another dog hit could cause the system to disengage again.

[0087] In addition, a further advantageous method variant provides for the current consumption of the electric motor direct drive of the shift drum to be recorded and evaluated in connection with individual, selected, or all gear change operations performed. Since it is generally technically possible and sensible to record the current consumption of the drive motor for the shift drum during all gear change operations, this monitoring can be advantageously used to detect mechanical overload based on the exceedance of a current consumption limit.

[0088] This creates a function in the method according to the invention and in the transmission control to protect at least the electronic components and the electrical components from overloading due to excessively high electrical currents.

[0089] A variant of the method can provide that, while recording the current consumption of the electric motor direct drive of the shift drum, the current is monitored to determine whether a defined threshold value is exceeded or not reached. After the threshold value is exceeded, a current integral is calculated, which is reset to zero if the threshold value is subsequently undershot. The current flowing through the motor windings and the power / control electronics is continuously measured, and a check is made to determine whether a threshold value is reached. If the threshold value is reached or exceeded, a current integral is calculated, which is reset to zero if the threshold value is undershot.

[0090] In another variant of the method, the current integral can be continuously calculated, so that after a limit value is exceeded, at least the drive control of the shift drum is interrupted, thus suppressing further switching operations. In this context, and after the definable limit value is exceeded, the entire control system can be shut down to prevent overloads.

[0091] It may also be useful to reactivate the shift drum drive control after a defined time interval. The control can then be released again after a defined time period, as it can then be assumed that the control has cooled down and is ready to continue operating.

[0092] However, the method can also provide that after this emergency shutdown occurs again or several times, a permanent emergency shutdown can or should take place, since in such cases it can or must be assumed that there is damage to the mechanics and / or the control system.

[0093] All events explained above, anomalies in the switching process or all errors that occur can also be logged, since each error case can be assigned a defined identification number, so that the user or an evaluation system can be informed unambiguously and clearly at what time which error or event occurred.

[0094] To achieve the aforementioned objects, the present invention proposes, in addition to the method explained in numerous variants, a torque- and / or speed-converting variable-speed transmission having an input shaft and an output shaft as well as at least two gear ratios, each of which is assigned at least one interchangeable gear pair. In the variable-speed transmission, shifting elements act on sliding sleeves that are connected to the gear pairs or the gears of the gear pairs and / or can be brought into operative engagement and can change them. The shifting elements engage with a shift drum that can be brought into defined angular positions and rotated between these angular positions.

[0095] The shift drum is coupled to an electromotive direct drive, formed in particular by a brushless DC motor or by a permanent magnet synchronous motor, which is designed to rotate the shift drum to change gear ratios and to bring it into the respective defined angular positions. In addition, at least one device and / or a sensor for detecting the electrical supply currents when the shift drum is actuated in connection with gear ratio change processes is assigned to the electromotive direct drive of the shift drum. In this way, the gear ratio change processes can be controlled at least on the basis of the detected supply currents of the electromotive direct drive of the shift drum, with further consideration of data on the rotational energies of the gears involved in the respective change process and / or the gear pairs in meshing engagement therewith.

[0096] The change-speed transmission according to the invention can, in particular, have a suitable device for controlling all gear-stage changes, which can preferably take into account the output signals of at least one sensor assigned to the shift drum, wherein the at least one sensor is provided for detecting rotational speeds and / or accelerations of the shift drum during gear-stage changes. Thus, since it is a direct drive, the respective position of the shift drum can be clearly reproduced. In principle, an absolute position sensor based on a contactless encoder can also be used as such a sensor, implemented, for example, by magnets fixed or glued into the shaft or the like.

[0097] It should be emphasized that the variable-speed transmission according to the invention can be operated with a control method according to one of the previously described embodiments for carrying out gear ratio change operations. The transmission can, in particular, be a sequentially shifting transmission.

[0098] It should be expressly noted at this point that all aspects and design variants explained in connection with the variable-speed transmission according to the invention equally relate to or can form partial aspects of the method according to the invention for controlling the transmission. Therefore, if certain aspects and / or relationships and / or effects are mentioned at any point in the description or in the claim definitions for the variable-speed transmission according to the invention, this applies equally to the method according to the invention.

[0099] The same applies in reverse, so that all aspects and design variants explained in connection with the control method according to the invention equally relate to or can be partial aspects of the variable-speed transmission according to the invention, which can be controlled in this way, i.e., by means of the method. Therefore, if at any point in the description or in the claim definitions for the method according to the invention, certain aspects and / or relationships and / or effects are mentioned, this applies equally to the variable-speed transmission according to the invention.

[0100] A brushless or torque motor can optionally be used as the drive motor for the shift drum drive. Due to its specific application, this motor falls under the category of so-called slow-speed motors. Such brushless or torque motors not only generally exhibit a high power density, but also require a relatively low supply power compared to previously used drive motors. A permanent magnet synchronous motor is also generally suitable as a drive motor for the shift drum drive; it can also exhibit a comparatively high power density and also requires a low supply power.

[0101] With a typical current consumption of less than one ampere for such torque motors or permanent magnet synchronous motors, weight and space can be saved, which is generally advantageous in mobile applications for vehicle drives. The drive motor can be designed either as an internal rotor or an external rotor.

[0102] In the following, exemplary embodiments will explain the invention and its advantages in more detail with reference to the accompanying figures. The relative sizes of the individual elements in the figures do not always correspond to the actual sizes, as some shapes are simplified and others are enlarged relative to other elements for better illustration. Fig. 1 shows a schematic perspective view of a bearing and arrangement configuration of a rotatable shift drum for a change gear and an electric motor direct drive coupled to the shift drum. Fig. 2A shows a schematic plan view of a design variant of a shift sleeve of a change gearbox. Fig. 2B shows a schematic side view of a toothed engagement of a shift sleeve according to Fig. 2A with a gear wheel of a sequentially shifting gearbox. Fig. 3A shows in a detailed view a contact situation of two teeth of a shift sleeve or a gear wheel in the beginning of tooth engagement. Fig. 3B shows an ideal switching process as well as an unsuccessful meshing process in the qualitative distance-time diagram. Fig. 3C shows an ideal switching process as well as an inverted and an overshooting meshing process in the qualitative path-time diagram.

[0103] In the following description of the figures, identical reference numerals are used for identical or equivalently functioning elements of the invention. Furthermore, for the sake of clarity, only those reference numerals are shown in the individual figures that are necessary for the description of the respective figure. The illustrated embodiments merely represent examples of how the shift drum of the variable-speed transmission according to the invention, including its electric direct drive, and a method for controlling the variable-speed transmission can be designed and do not represent a definitive limitation.

[0104] The schematic perspective view of the Fig. 1 illustrates a bearing and arrangement configuration of a rotatable shift drum 10 for a variant of a change-speed transmission not shown in detail here. The rotatably mounted shift drum 10 is coupled to an electric motor direct drive 12, which serves as the drive motor for the shift drum 10 and can rotate it in both directions as needed.

[0105] A part of the present invention not shown here is a torque- and / or speed-converting variable-speed transmission with an input shaft coupled, for example, to an internal combustion engine operable at a comparatively high speed level and across a wide speed range, and with an output shaft coupled, for example, to an axle or wheel drive of a vehicle that requires a significantly lower speed level than the internal combustion engine but higher torque than the latter. The same applies in principle to electric vehicle drives, because even with these drive motors, at least two gear ratios are normally useful, which can be provided equally by means of a mechanical variable-speed transmission for speed and torque conversion.

[0106] To enable speed and torque conversion between the combustion engine or electric motor and the axle or wheel drive of the vehicle, the change-speed gearbox (not shown here) has at least two gear ratios with at least two interchangeable gear pairs, wherein the gears of these at least two interchangeable gear pairs are each mounted on shafts and / or rotate on or with these shafts in a gearbox housing or on shafts mounted in another way. Typically, these gears are each assigned rotatable claw rings mounted on the shafts, which can be displaced axially on the shafts in order to be able to bring different gear pairs into meshing engagement depending on the desired gear ratio using the shift elements described below.

[0107] Since the change gear is, in particular, a sequentially shifting so-called dog-ring transmission or a so-called dog-box, the claw rings are designed as so-called dog rings, in which axial engagement with the corresponding dog rings occurs via a few large, slightly undercut teeth. The same number of teeth are found on the front sides of the gear wheels that can be engaged with the claw rings or sliding sleeves. The shift sleeves or claw rings and the gear wheels can each have four to six large teeth, for example, whereby the ratio between teeth and free space above the front engagement ring of the shift sleeves or claw rings and gear wheels can be approximately 30:70.

[0108] In order to be able to realize the desired gear engagements, the change gear comprises suitable shifting elements, for example in the form of movable shift forks, shift pins or the like (not shown here), which generally act on the sliding sleeves already mentioned but also not shown here, which are connected to the claw rings of the gear pairs or the gears of the gear pairs and can change them, which can mean in particular an axial displacement of the claw rings or sliding sleeves assigned to the gears on the bearing shafts.

[0109] The switching elements mentioned, which can be formed, for example, by movable or displaceable or pivotable shift forks or shift pins, are guided by the rotatable or pivotable shift drum 10 and are therefore in engagement with defined shaped slotted guides 14 and are in this way in operative connection with the shift drum 10 which can be brought into defined angular positions and rotated between these angular positions. In the exemplary embodiment shown, the slotted guides 14 are formed by grooved guides 16 running on the circumference of the shift drum 10 which is designed as a cylindrical shaft with a defined outer diameter and which can have curvatures 18 at some points along their circumferential course and end stops (not separately designated) at other points.

[0110] That such jumping out cannot always be prevented under certain circumstances with such dog-ring gearboxes is shown by the following Figuren 2A bis 3C explained in detail.

[0111] As the Fig. 1 As schematically indicates, the rotatable shift drum 10 has the shown electromotive direct drive 12, with the aid of which the shift drum 10 can be rotated very precisely by defined angles of rotation and thus brought into the respective defined angular positions. Optionally, the electromotive direct drive 12 of the shift drum 10 can be formed by a brushless DC motor 22 or by a permanently excited synchronous motor that is directly coupled to the shift drum 10, i.e., without the interposition of a gear or deflection or the like.

[0112] Such a drive motor 12, formed by a brushless DC motor 22 (or a permanent magnet synchronous motor), which, due to its specific application, can be classified as a so-called slow-speed motor, can also be referred to as a torque motor. Such torque motors exhibit relatively high torques at a comparatively low speed level, which is also required for the present application. The drive motor 12, via its direct coupling to the shift drum 10, acts directly on the shift elements to be moved. These shift elements, in turn, interact with the gear pairs of the change gear, possibly under load, and must shift them on the transmission shafts.

[0113] Even if in the Fig. 1 a frame arrangement for supporting the shift drum 10 and for fastening the drive motor 12 directly coupled to it can be seen, this frame construction is not necessarily to be understood as a concrete installation situation in a change-speed gearbox. However, a useful embodiment of the change-speed gearbox according to the invention can provide that the electromotive direct drive 12, which is directly coupled to the shift drum 10 and has a fixed rotary connection, is modularly pluggable and / or quickly interchangeable and / or replaceable without tools, which can be advantageous either for easy interchangeability with differently dimensioned drive motors 12 in different gearbox sizes and / or for easy accessibility for maintenance purposes.

[0114] Such brushless DC motors 22 or permanent magnet synchronous motors as rotary drives for shift drums 10 of change gears enable a high power density and thus a particularly compact design, so that any gear ratio stages between the shift drum 10 and the drive motor 12 can be dispensed with. Furthermore, such a compact motor 12 with high power density offers numerous advantages in terms of packaging, as there is a high degree of variability in the installation of the drive motor 12, which can be easily accommodated within the transmission housing, so that a shaft feedthrough for driving the shift drum 10 through the transmission housing to the outside can be omitted.

[0115] As explained above, the gearbox that is connected to the Fig. 1 shown shift drum 10, to a sequentially shifting transmission, which is designed as a so-called dog-box (not shown), which is characterized, among other things, by the fact that it can be shifted with comparatively short shift times and without the soft synchronization known from conventional change gearboxes.

[0116] One in Fig. 2A The shift sleeve 24 shown in a schematic plan view, as it can be used in such dog-ring gearboxes or dog-boxes, does not have the usual larger number of small engagement teeth for axial engagement with the gear wheels to be shifted, but only a few large teeth 26, which are also preferably slightly undercut, which, however, is not apparent in the schematic view of the Fig. 2A is not clarified.

[0117] The same number of teeth 26 is found on the front sides of the gear wheels 28 which can be brought into engagement with the sliding sleeves 24 (cf. the schematic view of the Fig. 2B ). The shift sleeves or sliding sleeves 24 and gear wheels 28 can, for example, each have four to six large teeth 26, wherein above the front engagement ring of the shift or sliding sleeves 24 and gear wheels 28, the ratio between tooth 26 and free space 30 can be approximately 30:70, which is intended in particular to reduce the risk that during the shifting process, in which the shift or sliding sleeve 24 actuated by a shift fork (not shown) is displaced on the transmission shaft 32 in the axial direction 34 against the front side of the gear wheel 28, a tooth 26 of the shift sleeve or sliding sleeve 24 strikes a tooth 26 of the gear wheel 28, as can be seen from the schematic side view of the Fig. 2B can be removed.

[0118] In shifting practice, it has been shown that for smooth shifting processes in which the teeth 26 mesh seamlessly, numerous control measures are sensible and necessary, as are the subject of the present invention. Thus, it is fundamentally sensible to take into account at least the rotational energies of the affected gears and / or the gear pairs meshing with them when activating or deactivating a gear ratio and / or when changing gear ratios of the change gear. This applies, for example, when disengaging the sliding sleeve 24 from a gear 28 of the gear pair of a first gear ratio, in which the at least one sliding sleeve 24 is axially displaced and brought out of engagement with the gear of the gear pair of the first gear ratio (not shown here).

[0119] This also applies when establishing an engagement of the sliding sleeve 24 with a gear 28 of the gear pair of a second transmission stage, in which the sliding sleeve 24 also moves axially (in direction 34, cf. Fig. 2B ) and brought into engagement with the gear 28 of the gear pair of the second gear ratio. During these shifting, shifting, and gear changing processes, the rotations of the shift drum 10 (cf. Fig. 1 ) is adapted to the respective speeds of the gears 28 to be brought into engagement or out of engagement with the sliding sleeves 24, wherein at least the rotational energies of the gears 28 concerned and / or gear pairs in meshing engagement therewith are taken into account at the same time.

[0120] The implementation of such shifting sequences as described here requires the use of electronic shifting programs for the rotations of the shift drum 10 and the resulting actuation steps of the shift forks or shifting elements which interact with the sliding or shift sleeves 24, wherein these electronic shifting programs are capable of taking into account the most diverse boundary conditions and conditions and / or of accessing different characteristic maps which are necessary for trouble-free and fast shifting processes.

[0121] One of these core functions is to minimize any overshoot and / or undershoot of an actual position that may occur during the adjustment of a target position corresponding to a target gear. These conditions pose the risk of the respective target gear being disengaged again, which can result in damage to the mechanism, particularly to the affected shift sleeve and / or the dog ring engaged or affected by it. Furthermore, premature braking of the gear pair of the target ratio, depending on the control difference of the positions, is also not advisable, as this can lead to damage during gear engagement and can also result in a significant loss of shifting performance.

[0122] As explained above and as shown by the Figuren 2A und 2B As illustrated schematically, the dog rings or shift sleeves 24 of sequential transmissions have a comparatively small number of teeth 26, which also usually have undercuts, so that a comparatively hard engagement between the corresponding toothings of the shift sleeves 24 and the adjacent frontal dog rings of the gear wheels 28 of the various gear ratio stages takes place and must take place for a successful shifting process.

[0123] During an engagement process for the sliding sleeve 24 into a gear 28 of a second gear stage to be activated, a positive fit must be sought by recording a torque and / or speed curve of the electric motor direct drive 12 of the shift drum 10 and / or the speed curves of the rotating transmission parts, such as the transmission shaft 32, and from this, determining whether the sliding sleeve 24 was able to engage the gear 28 of the second gear stage to be activated. In this case, when moving a dog ring or a sliding sleeve 24 toward a gear 28 of a target gear, an attempt is made to find the appropriate "gap" in order to mesh the dog rings.At the same time, by recording the speed curve and the current consumption in the drive motor 12 for the shift drum 10, it can be detected whether the dog "engages" and engages or "jumps back", which is transmitted as an impulse via the shift fork and introduced into the shift drum 10.

[0124] During each gear shift, there is a fundamental probability of hitting a so-called dog or tooth 26 of the target gear. The dogs or teeth 26 of the target gear corresponding to the dogs or teeth 26 of the shift sleeve 24 are mounted on the gear ring 28 of the target gear and are thus part of the rotating components of the transmission. Several dogs or teeth 26 are attached to a transmission gear at an angular distance. The distance between two dogs or teeth 26 that span a common angle is called the dog window, which in Fig. 2A and in Fig. 2B as a free space 30 between adjacent teeth 26. The dog or tooth 26 located on the shift sleeve 24, which is moved into the target gear with the shift fork, is mechanically separated from the dog rings or gear wheels 28 of the gears and, in order to engage a gear, must be transported into a dog window or free space 30 of the target gear.

[0125] Applies according to Fig. 3A During the axial displacement 34 of the dog or tooth 26 of the shift sleeve 24 onto a dog or tooth 26 of the gear wheel 28 of the target gear during the meshing phase, i.e., within an axially defined contact area 36 or the so-called dog window 36, an impulse is converted which results in energy being transferred to the shift fork. Depending on the energy input, the translational vector of the shift fork may be inverted, and the target gear may be disengaged again towards the initial gear. In this context, this process is also referred to as a dog-to-dog event.

[0126] It has been proven that these faulty meshing processes, known as dog-to-dog events, can occur relatively frequently during any gearshift. Since these events lead to pronounced discontinuities in the control sequences, it is useful to detect such dog-to-dog events in order to initiate appropriate countermeasures.

[0127] For this purpose, the method according to the invention provides a specific algorithm that detects such a dog-to-dog event based on the speed and direction of movement of the actuator or the shift element actuated by the shift drum 10 or the shift fork moved by the shift drum 10. This detection can possibly be performed indirectly via the analysis of the current consumption and the speed curve of the drive 12 of the shift drum 10, since the specific characteristics of such dog-to-dog events can be determined quite precisely and are thus also recognizable in the normal shifting sequence.

[0128] In particular, when a dog-to-dog event is detected, it can be checked whether the direction of rotation is inverted during movement within a certain angular window of the actuator or shift drum 10, or whether the speed gradient exhibits a significant discontinuity. If this is the case, the algorithm sends information to all other software components.

[0129] The Fig. 3B illustrates, using a schematic and qualitatively understandable diagram, an ideal switching sequence 38 over the switching time t, in which the switching path s already jumps at a switching time t 0 to a switching path s 1 which corresponds to an engaged gear ratio with fully engaged teeth 26 of sliding sleeve 24 and gear wheel 28 (cf. Fig. 2B ) corresponds.

[0130] However, since such an ideal switching sequence 38 cannot be realized in practice, after the quite likely occurrence of a dog-to-dog event, which may correspond to an unsuccessful engagement process and / or the unsuccessful attempt to establish engagement between the sliding sleeve 24 and the gearwheel 28 of the second gear ratio to be activated, the engagement process must be repeated at least once, if necessary several times, by correspondingly turning back and rotating the shift drum 10 with the shift fork guided accordingly.

[0131] Such a possible real switching sequence 40 is shown in Fig. 3B illustrated by the solid curve, which has a first step 42 at a time t 1 with a reversal of the direction of movement of the shift travel s, which illustrates an inversion 42 of the translational vector of the shift fork and the associated disengagement of the dog away from the target gear back towards the initial gear. If this inversion 42 is not counteracted by a renewed positive rotational movement of the shift drum 10 with a corresponding movement of the shift fork and the associated renewed displacement 34 of the shift sleeve 24 in the direction of the gear wheel 28, which corresponds to a partial repetition of the shifting process, the curve takes the interrupted course downwards in the direction s 0 , which corresponds to a failed meshing process at time t 2 with teeth 26 of the shift sleeve 24 not meshing properly, which is a so-calledDog-to-dog situation with a pronounced kickback or rebound of the shift sleeves.

[0132] Another possible real switching sequence 40 is shown in Fig. 3C by the solid curve which, according to the first paragraph 42, at a time t 1, shows the Fig. 3B shown reversal of the direction of movement of the shift travel s, which means an inversion 42 of the translational vector of the shift fork and the concomitant disengagement of the dog from the target gear back towards the initial gear. However, this inversion 42 is counteracted at time t 3 by a renewed positive rotational movement of the shift drum 10 with corresponding movement of the shift fork and the concomitant renewed displacement 34 of the shift sleeve 24 in the direction of the gear wheel 28, but with a stronger impulse than is reasonable, which produces an overshoot 44, which is shown as a dash-dotted curve in Fig. 3C is illustrated. If the switching travel were not limited by the stop at s1, the axial displacement of the switching sleeve 24 would extend beyond this stop s1 and possibly swing back in the manner shown at a time t4.

[0133] As the Figuren 3B and 3CTo illustrate, the repeatedly occurring dog-to-dog events and the associated faulty engagement processes or engagement attempts can be detected and / or recognized at least on the basis of the detection of the rotational speeds of the gearwheel or gearwheels of the second gear ratio and / or on the basis of the detection of the rotational speed and / or the angle of rotation of the selector shaft 10 and / or the drive torque of the electric motor direct drive 12 that must be applied to rotate the selector shaft 10. The period between the start of the gearshift process at t0 and the end of the desired successful engagement process between t3 and t4 is relevant here (cf. Fig. 3B and Fig. 3C ).

[0134] It checks whether the direction of rotation reverses during movement within a certain angular window of the actuator or switching shaft 10 that falls within this period, or whether the speed gradient exhibits a significant discontinuity. If this is the case, the algorithm sends a message to all other software components that it is advisable to restart and repeat the switching process.

[0135] Basically, according to Fig. 3C It is advisable to interrupt the shifting process early upon detection of a dog-to-dog event and to reverse the previously inverted "back" shifting movement of the shift fork as quickly as possible in order to attempt another shifting operation. In this way, part of the expended actuating energy, which was transmitted by the impulse, can be converted to direct the movement vector of the shift fork and the sliding sleeve 24 moved by it back toward the target gear. These detection steps may be repeated several times, although identical repetition processes do not always have to follow one another, as the shifting operations may have been aborted at different times. However, essentially the same measures are repeated when the target gear is to be engaged again.

[0136] In general, it is useful in the described method variants to record and evaluate the current consumption of the electric motor direct drive 12 of the shift drum 10 in connection with individual, selected, or all gear change operations performed. Since it is generally technically possible and useful to record the current consumption of the drive motor 12 for the shift drum 10 during all gear change operations, this monitoring can be advantageously used to detect mechanical overload based on the exceedance of a limit value for the current consumption. This creates a function in the method according to the invention and in the transmission control to protect at least the electronic components and the electrical components from overload due to excessive electrical currents.

[0137] All events explained above, inconsistencies in the switching sequence or all errors that occur can also be logged, since each error case can be assigned a defined identification number, so that the user or an evaluation system can be informed unambiguously and clearly at what time which error or event occurred.

[0138] The invention has been described with reference to a preferred embodiment. However, it is conceivable to a person skilled in the art that modifications or variations of the invention can be made without departing from the scope of the following claims. Bezugszeichenliste

[0139] 10Shift drum 12Direct drive, electric motor direct drive 14Coil guide 16Groove guide 18Curvature 22Drive motor, DC motor, brushless DC motor 24Shift sleeve 26Tooth, claw 28Gear, gear wheel 30Free space (between adjacent teeth or claws) 32Gear shaft 34Axial displacement direction 36Contact area, dog window 38Ideal switching sequence 40Real switching sequence 42Inversion 44Overshoot

Claims

1. A method used to control a torque-converting and / or speed-converting variable-speed transmission, which has an input shaft and an output shaft and at least two gear ratios, each of which is assigned at least one changeable gear pair, - wherein shifting elements act on sliding sleeves that are connected to the gear pairs or to the gearwheels of the gear pairs and are able to change these, - wherein the shifting elements are in engagement with a shift drum (10), which is bringable into defined angular positions and rotatable between these angular positions, - wherein the shift drum (10) is coupled with an electric-motor direct drive (12), which rotates the shift drum (10) and brings it into the particular defined angular positions in order to change gear ratios, - and wherein, upon activating or deactivating a gear ratio and upon changing gear ratios of the variable-speed transmission, the rotations of the shift drum (10) are coordinated with the particular rotational speeds of the gearwheels (28) to be brought out of or into engagement with the sliding sleeves (24), - wherein in each case at least the rotational energies of the gearwheels (28) in question and / or of gear pairs in meshing engagement therewith are taken into account at the same time.

2. The method according to claim 1, in which the rotational energies of the rotating parts in engagement with the particular gearwheels (28) involved in a change of a particular gear ratio are taken into account.

3. The method according to claim 1 or 2, in which the rotational energies for different gear ratios are each weighted differently and / or are taken from tables or characteristic maps and each taken into account differently.

4. The method according to one of the claims 1 to 3, in which the rotational energies of the shift drum (10) and / or of the electric-motor direct drive (12) driving the shift drum (10) are taken into account complementarily or separately.

5. The method according to one of the claims 1 to 4, in which the electric-motor direct drive (12) of the shift drum (10) is electronically coupled with a drive control of a drive motor, wherein a drive torque of the drive motor is reduced during and / or in preparation of a disengaging operation of a sliding sleeve (24) from a gearwheel (28) of a first gear ratio to be deactivated.

6. The method according to claim 5, in which the shift fork in operative engagement with the sliding sleeve (24) is preloaded with a defined and / or variable preload force during the disengaging operation, wherein the preload force is less than a shift force, which is only exerted on the shift fork when the drivetrain is load-free.

7. The method according to claim 5 or 6, in which the disengaging operation is performed after a shift request with a defined delay and in coordination with the behaviour of the drive motor of which the drive torque has previously been reduced.

8. The method according to one of the claims 1 to 7, in which, in preparation of or during an engaging operation, while the sliding sleeve (24) previously disengaged from the gearwheel of the deactivated first gear ratio is approaching an adjacent gearwheel (28) of a second gear ratio to be activated, a positive fit is found out for the sliding sleeve (24) by detecting a torque curve and / or speed curve of the electric-motor direct drive (12) of the shift drum (10) and identifying therefrom whether the sliding sleeve (24) has established the engagement with the gearwheel (28) of the second gear ratio to be activated.

9. The method according to claim 8, in which, after an unsuccessful engaging operation and / or after an unsuccessful attempt to establish an engagement between sliding sleeve (24) and gearwheel (28) of the second gear ratio to be activated, the engaging operation is repeated at least once or several times by repeated rotation of the shift drum (10) with correspondingly guided shift fork.

10. The method according to claim 8 or 9, in which an unsuccessful engaging operation and / or an unsuccessful attempt to establish an engagement between sliding sleeve (24) and gearwheel (28) of the second gear ratio to be activated is detected and / or identified at least based on the detection of the rotational speeds of the gearwheel (28) or gearwheels (28) of the second gear ratio and / or based on the detection of the angular velocity and / or of the rotation angle of the shift drum (10) and / or of the drive torque of the electric-motor direct drive (12) to be applied for the rotation of the shift drum (10).

11. The method according to one of the claims 8 to 10, in which at least the movement speed and the movement curve of the shift fork and / or of the shift drum (10) actuating the shift fork are detected and analysed in connection with an incomplete engaging operation and therewith associated jamming and / or catching of the sliding sleeve (24) with the gearwheel (28) of the second gear ratio.

12. The method according to claim 11, in which an actuating power and / or a rotational speed of the shift drum (10) is reduced and / or varied in an oscillating manner once or several times in connection with an incomplete engaging operation and therewith associated jamming and / or catching of the sliding sleeve (24) with the gearwheel (28) of the second gear ratio.

13. The method according to claim 11 or 12, in which a rotational speed of the shift drum (10) is reduced and / or inverted once or several times in connection with an incomplete engaging operation and therewith associated jamming and / or catching of the sliding sleeve (24) with the gearwheel (28) of the second gear ratio.

14. The method of one of the claims 8 to 13, in which at least the movement speed and the movement curve of the shift fork and / or of the shift drum (10) actuating the shift fork are detected and analysed in connection with a nearly complete or a complete engaging operation and therewith associated fit of the sliding sleeve (24) with the gearwheel (28) of the second gear ratio and after a return movement of the sliding sleeve (24) out of the fit with the gearwheel (28) of the second gear ratio into the gearwheel of the disengaged first gear ratio.

15. The method of one of the claims 8 to 13, in which at least the movement speed and the movement curve of the shift fork and / or of the shift drum (10) actuating the shift fork are detected and analysed in connection with an incomplete engaging operation and therewith associated jamming and / or catching of the sliding sleeve (24) with the gearwheel (28) of the second gear ratio and after a return movement of the sliding sleeve (24) out of the fit with the gearwheel (28) of the second gear ratio into the gearwheel of the disengaged first gear ratio.

16. The method according to one of the claims 8 to 15, in which at least the movement speed and the movement curve of the shift fork and / or of the shift drum (10) actuating the shift fork are detected and analysed in connection with an incomplete engaging operation and therewith associated jamming and / or catching of the sliding sleeve (24) with the gearwheel (28) of the second gear ratio and after a return movement of the sliding sleeve (24) out of the fit with the gearwheel (28) of the second gear ratio without establishing an engagement with the gearwheel of the disengaged first gear ratio.

17. The method according to one of the claims 8 to 15, in which at least the movement speed and the movement curve of the shift fork and / or of the shift drum (10) actuating the shift fork are detected and analysed in connection with a nearly complete or a complete engaging operation and therewith associated fit of the sliding sleeve (24) with the gearwheel (28) of the second gear ratio and after a return movement of the sliding sleeve (24) out of the fit with the gearwheel (28) of the second gear ratio without establishing an engagement with the gearwheel of the disengaged first gear ratio.

18. The method according to claim 16 or 17, in which, after identified return movement of the sliding sleeve (24) out of the fit with the gearwheel (28) of the second gear ratio, an amplified and / or extended and / or at least partially or in sections repeated shift pulse for the movement of the shift fork is initiated by the electric-motor direct drive (12) for the shift drum (10).

19. The method according to one of the claims 8 to 18, in which, by detection and evaluation of the rotational energies stored in the gear pairs and / or in the shift drum (10), a sliding speed below a defined minimum shift speed is identified for the sliding sleeve (24), and a rotational speed of the gear pair of the second gear ratio to be brought into engagement is increased.

20. The method according to one of the claims 1 to 19, in which a current consumption of the electric-motor direct drive (12) of the shift drum (10) is detected and evaluated in each case in connection with change operations of gear ratios.

21. The method according to claim 20, in which the exceeding or falling below of a defined threshold value is monitored during the detection of the current consumption of the electric-motor direct drive (12) of the shift drum (10), wherein, after an exceeding of the threshold value, a current integral is calculated, which is reset to a value of zero upon a subsequent falling below of the threshold value.

22. The method according to claim 21, in which the current integral is continuously calculated, wherein, after exceeding a limit value, at least the drive control of the shift drum (10) is interrupted and further shift operations are thereby suppressed.

23. The method according to claim 21 or 22, in which the drive control of the shift drum (10) is reactivated after a defined time interval has elapsed.

24. A torque-converting and / or speed-converting variable-speed transmission, which has an input shaft and an output shaft and at least two gear ratios, each of which is assigned at least one changeable gear pair, - wherein shifting elements act on sliding sleeves (24) that are connected to the gear pairs or to the gearwheels of the gear pairs and are able to change these in connection with change operations of gear ratios, - wherein the shifting elements are in engagement with a shift drum (10), which is bringable into defined angular positions and rotatable between these angular positions, - wherein the shift drum (10) is coupled with an electric-motor direct drive (12), which is designed to rotate the shift drum (10) and to bring it into the particular defined angular positions in order to change gear ratios, - and wherein the electric-motor direct drive (12) of the shift drum (10) is assigned at least one device and / or one sensor for the detection of the electric supply currents upon actuations of the shift drum (10) in connection with change operations of gear ratios, characterised in that - the variable-speed transmission is designed such that the control of the change operations of gear ratios is carried out at least based on the detected supply currents of the electric-motor direct drive (12) of the shift drum (10), further taking into account data on rotational energies of the gearwheels involved in the particular change operation and / or of gear pairs in meshing engagement therewith.

25. The variable-speed transmission according to claim 24, wherein the variable-speed transmission is furthermore designed such that its control of the change operations of gear ratios can take into account the output signals of at least one sensor assigned to the shift drum (10), wherein the at least one sensor is provided for the detection of rotational speeds and / or of accelerations of the shift drum (10) in change operations of gear ratios.