Method for quickly adjusting a gear ratio into underdrive on a drivetrain with a wrap-around gearbox

Abstract

Method for quickly changing a gear ratio into underdrive on a drive train (1) with a wrap-around transmission (2), wherein the drive train (1) comprises at least the following components: - a control unit (3) for setting an operating state of the drive train (1); - a wrap-around transmission (2) with a motor side (4) and an output side (5); and - at least one drive motor (6,7,8), the procedure comprises the following steps: a. using the control unit (3) to determine whether there is a need to quickly shift the transmission ratio on the wrap-around gear (2) into underdrive; b. if in step a. the aforementioned necessity is determined, the control unit (3) issues a first control command, whereupon a motor-side inertial torque is reduced; and c. if in step a. the said necessity is determined, a second control command is issued by means of the control unit (3), whereupon a necessary adjusting force (9) is provided for a necessary duration to transfer the transmission at the wrap-around gear (2) to the underdrive, wherein step b. is performed before or during step c. the control unit (3) determines the necessity when: - an emergency deceleration is carried out; - such a high torque opposing the inertial torque is applied that a maximum design holding pressure (14) is to be maintained to prevent slippage of the wrapping element (15); and - a torque of such high frequency and high amplitude that changes direction is applied that a maximum holding pressure (14) is to be maintained to prevent slippage of the wrapping means (15), wherein the control unit (3) comprises an ABS system or is communicatively connected to an ABS system and the ABS system detects the output-side torque and / or provides the relevant control data, characterized in that in step b. the motor-side inertia-induced torque is reduced by the control unit (3) causing a torque opposing the inertia-induced torque to be applied to the drive machine, which is an electric drive machine (7, 8).

Description

[0001] The invention relates to a method for quickly adjusting a gear ratio into underdrive on a drive train with a wrap-around transmission, wherein the method comprises the following steps: a. Determine, using the control unit, whether there is a need to quickly shift the gear ratio on the wrap-around transmission into underdrive; b. if in step a. the aforementioned necessity is determined, the control unit issues a first control command, whereupon an inertial torque on the motor side is reduced; and c. If the aforementioned necessity is determined in step a., the control unit issues a second control command, whereupon a necessary adjusting force is provided for a required duration to transfer the gear ratio at the wrap-around transmission to the underdrive. The method is characterized in particular by the fact that step b. is executed before or during step c. The invention further relates to a drivetrain and a motor vehicle with such a drivetrain.

[0002] US Patent 2011 / 0319225A1 discloses a method for adjusting the gear ratio of a wrap-around transmission in a drive train with a disconnect clutch between an electric motor and an internal combustion engine.

[0003] DE 10 2012 208 320 A1 discloses a motor vehicle comprising an internal combustion engine, a continuously variable transmission which can be hydraulically actuated by means of a pump device and a control device.

[0004] JP 2019- 70 427 A discloses a motor vehicle comprising a drive unit, a continuously variable transmission and a control unit.

[0005] DE 198 33 699 A1 discloses a method for adjusting the transmission ratio of a continuously variable automatic transmission with a variator.

[0006] In a wrap-around transmission, the wrapping element must be constantly pressed against the drive shaft to prevent slippage. This is usually achieved by hydraulic pressure, supplied by a hydraulic system with a pump (e.g., electric) or by an internal combustion engine (with a rail system). An additional flow rate is required to adjust the gear ratio. The faster the gear ratio needs to change, the greater the required flow rate. A critical scenario for the design of such a hydraulic system is the rapid adjustment of the gear ratio towards underdrive during emergency braking, i.e., when a vehicle decelerates rapidly.The contact pressure for the wrapping element must be high enough to prevent slippage, while simultaneously a high flow rate is required to change the gear ratio as quickly as possible. Due to system requirements, the gear ratio must usually be changed while the vehicle is still rolling. For most applications, it is essential that a vehicle always comes to a stop in or near underdrive to ensure that it can start moving again even on a steep incline. It should be noted that the required contact pressure increases with the amount of torque to be transmitted. In the case of rapid gear changes during emergency braking, the transmitted torque results from the dynamic torque due to the acceleration of the transmission input side and the torque of the drive motor (drag torque).With currently known solutions, rapid adjustment into underdrive cannot be guaranteed, or the system is oversized for most or all other application states of the wrap-around gearbox.

[0007] Based on this, the present invention aims to overcome, at least partially, the disadvantages known from the prior art. The features of the invention are defined in the independent claims, for which advantageous embodiments are shown in the dependent claims. The features of the claims can be combined in any technically meaningful way, whereby the explanations in the following description and features from the figures, which comprise supplementary embodiments of the invention, can also be used.

[0008] The invention relates to a method for quickly adjusting a gear ratio into underdrive on a drive train with a wrap-around transmission, wherein the drive train comprises at least the following components: - a control unit for setting an operating state of the drive train; - a wrap-around transmission with a motor side and an output side; and - at least one drive motor, the procedure comprises the following steps: a. Determine, using the control unit, whether there is a need to quickly shift the gear ratio on the wrap-around transmission into underdrive; b. if in step a. the aforementioned necessity is determined, the control unit issues a first control command, whereupon an inertial torque on the motor side is reduced; and c. if the aforementioned necessity is determined in step a., a second control command is issued by means of the control unit, whereupon a necessary adjusting force is provided for a necessary duration to transfer the translation at the wrap-around gear towards the underdrive.

[0009] The procedure is characterized primarily by the fact that step b. is performed before or during step c.

[0010] In the following, reference is made to the aforementioned direction of travel (also referred to as the longitudinal direction) when, unless explicitly stated otherwise, the perpendicular transverse and axial directions, which therefore span a Cartesian coordinate system, and corresponding terms are used. When the direction of travel, the axial direction, and the transverse direction are mentioned here, both the positive and negative directions within the spanned coordinate system are meant. Furthermore, reference is made to the wrapping element, which, in the assembled state, forms a circle of wrap around the set circles of action of the two pairs of conical discs of a wrapping mechanism. With regard to the circle of wrap, the terms "inside" (i.e., the wrapping element enclosed in the (imaginary) plane of the circle of wrap) and "outside" are used, respectively.

[0011] Unless explicitly stated otherwise, ordinal numbers used in the preceding and following descriptions serve solely for unambiguous differentiation and do not indicate any order or ranking of the components referred to. An ordinal number greater than one does not necessarily imply the presence of another such component.

[0012] The drivetrain described here, with its wrap-around transmission, for example a so-called conical disc wrap-around transmission or CVT [continuous variable transmission], is designed in a conventional manner. In one embodiment, the drivetrain is configured as a so-called P2 hybrid system, in which a first disconnect clutch (K1) is provided between an internal combustion engine and an electric drive motor (traction motor), and a second disconnect clutch (K2) is provided between the electric drive motor and the wrap-around transmission. This hybrid configuration has the advantage that purely electric driving is possible, as is charging a traction battery (in the vehicle while the vehicle is stationary) while no torque is supplied to a consumer by the drive motors (K2 open).In an alternative embodiment, the drivetrain is configured as a P0 hybrid, P1 hybrid, or P2.5 hybrid. It should be noted that the method is also fundamentally suitable for a hybrid configuration in which no disconnect clutch is provided on the motor side of the wrap-around transmission. Most importantly, however, the method is suitable for a hybrid configuration in which no disconnect clutch is provided between the output side of the wrap-around transmission and a consumer, so that the output side of the wrap-around transmission is permanently and rigidly connected to a consumer, for example, the drive wheels in a motor vehicle, thus transmitting torque.

[0013] In the process, the control unit determines in step a that there is a (current) need to quickly shift the gear ratio of the wrap-around transmission into underdrive. A rapid shift is necessary, for example, during emergency braking of a vehicle or in a situation detected by the vehicle's safety electronics where underdrive should be reached as quickly as possible, or where a standstill of the drive wheels is a likely or most likely outcome. It should be noted that in one embodiment, the control unit itself does not include any sensors designed to detect such a need.Rather, the control unit is then connected to at least one other component in a communicative manner, which signals the necessity to the control unit or provides the data by means of which the control unit is able to decide whether this necessity exists.

[0014] In step b., once the need for a rapid shift of the transmission into underdrive has been determined, the control unit issues a first control command. This first command reduces the inertial torque emanating from at least one drive motor. This is achieved either by opening a corresponding disconnect clutch, which decouples the drive motor in question, and / or by inducing a counter-torque in the drive motor, in which case the drive motor is electric. With multiple drive motors, the torque is reduced by opening the respective disconnect clutch or by inducing a counter-torque in each case (if the drive motor is electric).As a result, for example, one of the drive motors remains connected, with a counter-torque being induced, and one of the drive motors is decoupled from the motor side of the wrap-around transmission by means of a disconnecting clutch. In yet another embodiment, only one or more of a plurality of drive motors are decoupled from the motor side of the wrap-around transmission, or a counter-torque is induced in only at least one of a plurality of electric drive motors.

[0015] In step c., a second control command is issued in response to this necessity (for a rapid shift of the transmission into the underdrive), with the result that the necessary adjustment force is provided for a necessary (time) duration in order to transfer the wrap-around transmission to the underdrive as quickly as necessary or as quickly as possible.

[0016] It should be noted that with a suitable design of the control system for the wrapping mechanism, the necessary adjustment force is not necessarily (and usually not) constant over time and is subject to a separate control procedure. As already mentioned at the beginning, the (maximum) torque to be transmitted for the detected operating condition is taken into account, thus reliably preventing the wrapping element from slipping.

[0017] It is proposed here that step b. (i.e., reducing the motor-side inertia-related torque) be performed before or during step c. (i.e., transferring the gear ratio towards the underdrive). By performing step b. during or before step c., the required clamping force across the wrap-around transmission is significantly reduced, at least for a portion of step c., due to the reduced torque differential. This allows a larger proportion of the adjustment force to be available for transferring the gear ratio to the underdrive. This is particularly advantageous for a hydraulically operated wrap-around transmission, as it requires a lower flow rate for transferring the gear ratio to the underdrive.

[0018] According to the invention, in step b. the inertia-related torque on the motor side is reduced by the control unit causing the following: a torque opposing the inertia-induced torque is applied to the drive machine, which is an electric drive machine.

[0019] It is further proposed in an advantageous embodiment of the method that in the event that in step b the drive train still includes at least one disconnect coupling between the wrap-around gearbox and at least one of the drive motors: at least one, preferably a single, of the disconnect couplings is opened, preferably the disconnect clutch arranged between the wrap-around transmission and the drive engine, which is an internal combustion engine, is opened.

[0020] It is proposed here that step b. be carried out by applying a torque to an electric drive motor that opposes the inertial torque. This opposing torque relates solely to the inertia of the drive motor itself, i.e., the rotor, and / or additionally to the inertia or dynamic inertia of another connected drive motor, especially an internal combustion engine.

[0021] Additionally or alternatively, the inertia of at least one of the drive motors is decoupled from the motor side of the wrap-around transmission via an existing disconnect clutch. In one embodiment, for example, a disconnect clutch is engaged between the electric drive motor and the motor side of the wrap-around transmission, whereby the electric drive motor remains connected to the internal combustion engine. Preferably, the inertia of the decoupled drive motors is recuperated.

[0022] In one embodiment, the internal combustion engine is directly connected to the motor side of the wrap-around transmission by means of a disconnect clutch. In this case, this disconnect clutch is preferably opened.

[0023] In another embodiment, an electric drive motor is interposed, as in a P2 hybrid configuration. In this case, the disconnect coupling designated K1 (see above) and / or the disconnect coupling designated K2 is opened.

[0024] In another configuration, an electric drive motor is connected between or in parallel, but the disconnect clutch is only connected between the motor side of the wrap-around transmission and the internal combustion engine including the electric drive motor, so that when the corresponding disconnect clutch is opened, both the electric drive motor and the internal combustion engine are decoupled and the electric drive motor and the internal combustion engine cannot be separated from each other.

[0025] In a further advantageous embodiment of the method, it is proposed that step b. be completed before the start of step c. wherein preferably the wrapping gear and a further provided disconnect clutch are hydraulically actuated, wherein preferably the wrap-around transmission and the hydraulically actuated disconnect clutch are supplied from a common supply system.

[0026] In this advantageous embodiment, the torque is already reduced as much as possible, for example by opening a disconnect clutch, before step c. is initiated. This is particularly advantageous in a hydraulically operated wrap-around transmission, whereby the additional flow rate for a hydraulically operated disconnect clutch is fully available or is not affected by the high demand of step c.

[0027] In a suitable embodiment, the process, despite the sequential execution of steps b and c, is faster overall, or requires a lower maximum flow rate, than if steps b and c were executed at least partially in parallel. Furthermore, regardless of hydraulic actuation, the adjustment of the contact pressure on the wrapping mechanism is simplified by completing step b first. This significantly reduces the maximum contact pressure required for the wrapping element.

[0028] It should be noted that when the disconnect clutch and / or the wrap-around drive are actuated by an electric motor using this method in an embodiment as described here, it is advantageous, for example, with regard to the maximum available power voltage, thus reducing the consumption of the stored electrical energy of a traction battery. In a particularly advantageous embodiment, the deceleration energy can also be used, at least partially, for recuperation and thus for charging the traction battery. It should also be noted that the advantage of opening a disconnect clutch (if present) lies in the fact that the inertial torque, even under dynamic conditions such as those occurring during emergency braking with an anti-lock braking system, can be applied to the wrap-around device with a particularly low yet reliable contact pressure.This therefore enables a safe and particularly fast transition of the gear ratio towards underdrive.

[0029] The advantage of inducing a counter-rotating torque on the electric drive motor is that the non-decoupled electric drive motor is immediately available again for torque demand. This is advantageous, for example, for moving a vehicle out of a danger zone after or during emergency deceleration. If the internal combustion engine also remains engaged, a very large torque (e.g., the maximum available torque) is available in this case for (re-)accelerating the vehicle to move it out of a danger zone. A level crossing is one such example of a danger zone.

[0030] The decision as to which of these processes is used to reduce the inertial torque is made, for example, depending on the degree of deceleration and / or external information, such as a device for detecting a distance to obstacles, such as other vehicles in front of and / or behind the motor vehicle or rigid obstacles, such as a broken-down truck, and / or terrain information, for example from an interactive navigation system.

[0031] In a further advantageous embodiment of the method, it is proposed that the control unit determines the inertial torque by: - the rotational acceleration of the motor side is recorded; - the torque of the motor side is recorded; and / or - corresponding data from an engine control unit of at least one of the drive engines, preferably the internal combustion engine, are taken from the engine control unit.

[0032] In this embodiment, the rotational acceleration is detected directly at the motor side of the wrap-around drive or at a shaft rigidly or detachably connected to it. In an advantageous embodiment, rotational acceleration and / or torque is detected directly at the rotor shaft of an electric drive motor, wherein a motor controller is integrated into this drive motor (for example, as a single unit) and / or preferably, a command is communicated by the (for example, separate) control unit of the motor controller that the inertial torque should be compensated. The torque detected directly by an (integrated) motor sensor and recognized for motor commutation is then converted within the respective drive motor into a corresponding power voltage or power current.For sufficient control accuracy in motor commutation within a drive train, the sensor quality of the motor sensors is already sufficiently accurate in currently known systems, allowing the use of state-of-the-art components. This control loop is therefore very short and, generally (due to the high demands on motor commutation control accuracy), very precise. In the event that all drive motors are disconnected by opening the corresponding disconnect clutch, the rotational acceleration and / or torque is measured on the motor side of the wrap-around gearbox.

[0033] Torque is detected directly by means of a torque measurement or indirectly, for example from current data of an electric drive motor or state measurements before the start of deceleration. In one embodiment, the corresponding data from a motor control unit is used, whereby the torque is tapped from the provided data and / or can be determined from other values, such as boost pressure.

[0034] According to the invention, the control unit determines the necessity when, on the output side: - an emergency deceleration is carried out; - such a high torque opposing the inertial torque is applied that a maximum holding pressure, as designed, is required to prevent the wrapping element from slipping; and - such a high-frequency torque with high amplitude and changing direction is applied that a maximum holding pressure, as designed, is required to prevent the wrapping element from slipping. wherein preferably the control unit includes an ABS system or is connected to an ABS system in a communicating manner and the output-side torque is detected by the ABS system and / or the relevant control data is provided.

[0035] In this embodiment, the emergency deceleration itself, for example during emergency braking of a motor vehicle, is detected, for example by means of force or displacement measurement at a brake sensor, such as a brake pedal in a motor vehicle. Alternatively or additionally, detection is carried out via an acceleration sensor (preferably translational in the case of a drive train for propulsion and rotational in the case of torque supply).

[0036] In one embodiment, it is found that the torque differential across the wrap-around drive is so high that a holding pressure of such a high (e.g., maximum) level must be maintained to prevent slippage of the wrap-around drive's wrapping element, thus ensuring that underdrive is not reached within a desiredly short time. It should be noted that in such a case, deceleration is detected as borderline earlier than in a conventional emergency deceleration.

[0037] Alternatively or additionally, the frequency (change frequency) and magnitude (torque amplitude) of a torque direction change are recorded or estimated, based on which, as a safety precaution, a very high holding pressure is set, resulting in the same consequence as described in the previous paragraph. A high-frequency change of direction with a high torque amplitude occurs, for example, when an anti-lock braking system (ABS) in a motor vehicle ensures that a drive wheel repeatedly approaches or reaches a lock-up and the lock-up is repeatedly released, so that the controllability of the motor vehicle is maintained and / or optimal deceleration is achieved by preventing excessive loss of traction between the tire and the road surface.

[0038] In a particularly advantageous embodiment, not only the torque data are recorded, but also the control data of an ABS system are used, so that an applied torque for the corresponding control of the holding pressure on the wrap-around gear is known even before or during the intervention of the ABS system.

[0039] In a further advantageous embodiment of the method, it is proposed that an electric drive motor for torque transmission is permanently connected to the wrapping gear, wherein a torque opposing the inertia-induced torque is applied to the permanently connected electric drive motor.

[0040] In this embodiment, a second electric drive motor is preferably permanently connected to the wrap-around transmission for torque transmission. This permanently connected electric drive motor is, for example, also configured for recuperation and / or has a comparatively small rotor diameter and thus a comparatively low moment of inertia, because this electric drive motor is optimized for efficient continuous operation rather than for high torque. Preferably, the optionally provided decoupleable electric drive motor is configured for boosting or starting (or starting) an internal combustion engine. Preferably, a counter-rotating torque is applied to this permanently connected electric drive motor to reduce the torque caused by inertia, as described above.

[0041] According to another aspect, a powertrain is proposed comprising at least the following components: - a control unit for setting an operating state of the drive train; - a wrap-around transmission with a motor side and an output side; and - at least one drive motor, wherein the drive train is set up by means of the control unit to carry out the method according to an embodiment as described above, wherein preferably at least one disconnect coupling is further provided between the wrap-around transmission and at least one of the drive motors.

[0042] The drivetrain is designed to transmit torque supplied by at least one drive motor, for example, an internal combustion engine and / or an electric drive motor, and delivered via its machine shaft (e.g., the combustion engine shaft and / or the (electric) rotor shaft), as required, taking into account the necessary rotational speed and torque. One such application is, for example, an electric generator for the provision of electrical energy. To transmit the torque in a targeted manner and / or via a gearbox with different gear ratios, the use of the wrap-around transmission described above is particularly advantageous because a large gear ratio spread can be achieved in a small space, and the drive motor can be operated within a narrow optimal speed range.Conversely, it is also possible to capture inertial energy introduced by, for example, a drive wheel and transfer it to an electric generator for recuperation (i.e., the electrical storage of braking energy) using a recirculating transmission system, with a suitably configured torque transmission train. Furthermore, in a preferred embodiment, a plurality of drive motors are provided, which can be connected in series or parallel, or operated decoupled from one another, and whose torque can be supplied as needed by means of a recirculating transmission system as described above. An application example is a hybrid drive comprising an electric drive motor and an internal combustion engine.

[0043] With the proposed drivetrain, designed to execute the previously described procedure, the maximum power (i.e., the maximum pressure in the case of hydraulic actuation) can be reduced. At the very least, it is ensured that, due to a reduced (maximum) flow rate required to provide the necessary contact pressure, a larger proportion of the available (i.e., system-provided) flow rate can be used to engage the recirculating gear in underdrive, or sufficiently close to underdrive, during emergency deceleration before the drivetrain comes to a standstill. Furthermore, in a supply system with an electric pump, a reduction in the requested pressure (due to the reduced contact pressure for the recirculating gear) reduces the requested torque, and thus, assuming constant power, increases the rotational speed.This means that the flow rate on the supply side, i.e., the available flow rate, is also increased or can be increased. This allows, for example, the use of a recirculating gearbox with a very large spread, for example greater than four, and / or the use of a power system (preferably a hydraulic supply system) with smaller dimensions.

[0044] According to another aspect, a motor vehicle is proposed, comprising a drive train according to an embodiment as described above and at least one drive wheel, wherein the motor vehicle can be driven by means of at least one of the drive motors via the at least one drive wheel.

[0045] Most modern motor vehicles are front-wheel drive and often position the drive unit, such as an internal combustion engine and / or an electric motor, in front of the driver's cab and transversely to the vehicle's longitudinal axis. The radial installation space is particularly limited in such a configuration, making the use of a compact wrap-around transmission especially advantageous. A similar situation exists in motorized two-wheelers, which, compared to previously known two-wheelers, are required to deliver consistently higher performance within the same installation space. This challenge is further exacerbated by the hybridization of powertrains.

[0046] This problem is exacerbated in small cars according to European classification. The components used in a small car are not significantly smaller than those in larger car classes. Nevertheless, the available installation space is considerably smaller in small cars. A similar problem arises with hybrid vehicles, which incorporate multiple drive motors and clutches in the powertrain, resulting in limited overall installation space.

[0047] With the proposed vehicle, which includes a drivetrain for executing the previously described procedure, the maximum power (i.e., the maximum pressure in the case of hydraulic actuation) can be reduced. At the very least, it is ensured that, due to the reduced requirement for a (maximum) flow rate to provide the necessary contact pressure, a larger proportion of the available flow rate can be used, or the available flow rate can be increased, in order to engage the wrap-around transmission in underdrive, or sufficiently close to underdrive, during emergency deceleration before the vehicle comes to a complete stop. This allows, for example, the use of a wrap-around transmission with a very large spread, such as greater than four, and / or the use of a smaller power system (preferably a hydraulic supply system), thus saving installation space.

[0048] Passenger cars are assigned to a vehicle class based on criteria such as size, price, weight, and performance, although this definition is constantly evolving according to market needs. In the US market, vehicles in the subcompact and microcar classes are classified as subcompact cars according to European standards, while in the UK they correspond to the supermini and city car classes, respectively. Examples of microcars include the Volkswagen up! and the Renault Twingo. Examples of subcompact cars include the Alfa Romeo MiTo, Volkswagen Polo, Ford Ka+, and Renault Clio. Well-known hybrid vehicles include the BMW 330e and the Toyota Yaris Hybrid. Mild hybrids include the Audi A6 50 TFSI e and the BMW X2 xDrive25e.

[0049] According to another aspect, a computer program comprising computer program code is proposed, wherein the computer program code is executable on at least one computer such that the at least one computer is caused to execute the method according to an embodiment as described above, wherein at least one of the computers: - is integrated into a motor vehicle, preferably as an on-board computer or a component of an on-board computer; and / or - is set up for communication with an on-board computer of a motor vehicle.

[0050] According to another aspect, a computer program product is proposed on which the computer program code is stored, wherein the computer program code is executable on at least one computer in such a way that the at least one computer is caused to execute the method according to an embodiment as described above. where at least one of the computers: - is integrated into a motor vehicle, preferably as an on-board computer or a component of an on-board computer; and / or - is set up for communication with an on-board computer of a motor vehicle.

[0051] The invention described above is explained in detail below against the relevant technical background with reference to the accompanying drawings, which show preferred embodiments. The invention is in no way limited by the purely schematic drawings, although it should be noted that the drawings are not dimensionally accurate and are not suitable for defining size relationships. It is illustrated in Fig. 1: A wrap-around gear in a perspective view; Fig. 2: A drive train with a control unit in a schematic view; Fig. 3: a flowchart for a procedure for quickly shifting a gear ratio into underdrive; and Fig. 4: a motor vehicle with a drivetrain.

[0052] In Fig. Figure 1 shows a perspective view of a wrap-around drive 2. The wrap-around drive 2 has a wrap-around element 15, which transmits torque by connecting a motor-side pair of conical disks 19 to an output-side pair of conical disks 20. The motor-side pair of conical disks 19, which is rotatable about a motor-side axis of rotation 21, in turn has a first conical disk 22 (loose disk) and a second conical disk 23 (fixed disk), wherein a motor-side spread 24 is formed by a corresponding axial spacing of the first conical disk 22 and the second conical disk 23. The motor-side spread 24 thus defines a motor-side working circle 25 on which the wrap-around element 15 runs on the motor-side pair of conical disks 19.The output-side conical disk pair 20, which is rotatable about an output-side rotation axis 26, in turn has a third conical disk 27 (loose disk) and a fourth conical disk 28 (fixed disk), wherein an output-side spread 29 is formed by a corresponding axial spacing of the third conical disk 27 and the fourth conical disk 28. The output-side spread 29 thus establishes a second output-side working circle 30 on which the wrapping element 15 runs on the output-side conical disk pair 20. The motor-side spread 24 (i.e., the motor-side working circle 25) of the motor-side conical disk pair 19 and the output-side spread 29 (i.e., the output-side working circle 30) of the output-side conical disk pair 20 are each adjustable by means of a control unit 3. This results in an output-side speed 32 from a motor-side speed 31 and vice versa.The (variable) ratio of the two working circles 25, 30 thus yields the transmission ratio between the shafts of the motor side 4 and the output side 5. For this purpose, the control unit 3 of the motor-side conical disc pair 19 provides an adjusting force 9 to regulate the motor-side spreading dimension 24, whereby the (motor-side) adjusting force 9 acts parallel to the motor-side axis of rotation 21 and together with a holding pressure 14 (causing a minimum required contact pressure on the wrapping element 15). The control unit 3 of the output-side conical disc pair 20 also provides an adjusting force 9 to regulate the output-side spreading dimension 29, whereby this (output-side) adjusting force 9 acts parallel to the output-side axis of rotation 26. Optionally, the conical disc pairs 19, 20 can be hydraulically actuated, and the adjusting forces 9 are provided by means of hydraulic pressure.

[0053] In Fig. Figure 2 shows a drive train 1 with a control unit 3 in a schematic view. An internal combustion engine 6 includes an engine control unit 13, which is connected to a central control unit 3. A common supply system 12, simplified here as a pump, is provided for actuating the disconnect clutches 10, 11 and the wrap-around transmission 2. The wrap-around transmission 2 is connected with its output side 5 to a consumer with a braking device 33, for example, a left drive wheel 17, 18 (compare Figure 2). Fig. 4) connected, for example, controllable by an ABS system (not shown). A (purely optional) second electric drive motor 8 is permanently connected to the motor side 4 of the wrap-around transmission 2 (shown on the right) and transmits torque. Furthermore, a first electric drive motor 7 and the internal combustion engine 6 are connected to the motor side 4 of the wrap-around transmission 2 (shown on the left), and these can be decoupled from the motor side 4 by means of a first disconnect clutch 10 (K1) and a second disconnect clutch 11 (K2).

[0054] In Fig. Figure 3 shows a flowchart for a procedure for quickly shifting a gear ratio into underdrive. The following explanations refer to the terminology in the Fig. 2. In the described procedure, in step a. the control unit 3 determines that there is a (current) need to quickly shift the transmission ratio on the wrap-around gear 2 into underdrive, for example as a result of a detected or planned deceleration of the output-side rotational speed or, in use in a motor vehicle 16, as a result of the decrease in the speed of the motor vehicle 16.

[0055] In step b., if a rapid shift of the transmission into underdrive is necessary, the control unit 3 issues a first control command. This first control command reduces the inertial torque on the motor side by applying a torque opposite to the inertial torque, as per configuration i. According to configuration ii', the disconnect clutch closest to the wrap-around transmission 2 in the torque flow (in Fig. 2. The second disconnect clutch 11 (K2) between the wrap-around transmission 2 and the drive motors 6, 7, for example, only one internal combustion engine 6, is opened. According to configuration ii'', with a (second) disconnect clutch 11 (K2) between the wrap-around transmission 2 and a (first) electric drive motor 7, as well as a (first) disconnect clutch 10 between the (first) electric drive motor 7 and an internal combustion engine 6, the first disconnect clutch 10 (K1) is opened and the second disconnect clutch 11 remains closed. The (first) electric drive motor 7 thus remains torque-transmittingly connected to the motor side 4 of the wrap-around transmission 2. Then, according to the measure in configuration i, a counter-torque is induced in at least one of the non-decoupled electric drive motors 7, 8.

[0056] In step c, if a rapid shift of the transmission into the underdrive is necessary, a second control command is issued, resulting in the provision of the required adjustment force 9 for a necessary duration to shift the wrap-around transmission 2 into the underdrive as quickly as necessary or as quickly as possible. If step b (solely) involves opening a disconnect clutch, step c is preferably executed only after step b has been completed. If step b involves compensating for an inertial torque, step b is executed for at least part of the duration of step c, preferably starting only after step b has been initiated, i.e., when the inertial torque has already been reduced (as a result of a control command from the control unit 3).

[0057] In Fig.Figure 4 shows a drive train 1 in a motor vehicle 16 with a wrap-around transmission 2. The motor vehicle 16 has a longitudinal axis 34 and an engine axis 35, with the engine axis 35 being located in front of the driver's cab 36. The drive train 1 comprises a first drive motor 6, which is preferably designed as an internal combustion engine 6, and is connected to the wrap-around transmission 2 via an input shaft, for example, a combustion engine shaft, transmitting torque. A second drive motor 7, which is preferably designed as an electric drive motor 7, is also connected to the wrap-around transmission 2 via a rotor shaft, for example, transmitting torque. A second electric drive motor 8 is also provided (purely optionally), which is rigidly connected (i.e., without a disengaging clutch) to the wrap-around transmission 2 on the motor side, axially opposite the first drive motor, transmitting torque.A torque for the drive train 1 is delivered simultaneously or at different times by means of the drive motors 6, 7, 8 or via their machine shafts, whereby the first electric drive motor 7 and the internal combustion engine 6 can be decoupled together by means of a second disconnect clutch 11 (K2), and only the internal combustion engine 6 can be decoupled by means of a first disconnect clutch 10 (K1) from the motor side 4 of the wrap-around transmission 2. It should be noted that torque can also be received, for example by means of the internal combustion engine 6 for engine braking and / or by means of the electric drive motors 7, 8 for recuperation of braking energy.On the output side, the wrap-around transmission 2 is connected to a purely schematically represented output, so that a left drive wheel 17 and a right drive wheel 18 can be supplied with a torque from the drive machine 6,7 with variable transmission for the propulsion of the motor vehicle 16.

[0058] The method proposed here ensures that the gear ratio shifts into underdrive during emergency braking in any gear ratio state. Reference symbol list 1 Powertrain 2 wrap-around gears 3 Control unit 4 Engine side 5 Output side 6 Internal combustion engine 7 first electric drive motor 8 second electric drive motor 9 Adjustment force 10 first disconnect coupling 11 second disconnect coupling 12 Supply system 13 Engine control 14 Holding pressure 15 wrapping agents 16 motor vehicle 17 left drive wheel 18 right drive wheel 19 motor-side conical disc pair 20 output-side conical disc pair 21 motor-side rotation axis 22 first conical disc 23 second conical disc 24 motor-side spread dimension 25 motor-side working circle 26 output-side rotation axis 27 third conical disc 28 fourth cone disc 29 output side spread dimension 30 output-side working circle 31 engine-side speed 32 output side speed 33 Braking system 34 Longitudinal axis

Claims

[1] Method for quickly changing a gear ratio to underdrive on a drive train (1) with a wrap-around transmission (2), wherein the drive train (1) comprises at least the following components: - a control unit (3) for setting an operating state of the drive train (1); - a wrap-around transmission (2) with a motor side (4) and an output side (5); and - at least one drive motor (6,7,8), the procedure comprises the following steps: a. using the control unit (3) to determine whether there is a need to quickly shift the transmission ratio on the wrap-around gear (2) into underdrive; b. if in step a. the aforementioned necessity is determined, the control unit (3) issues a first control command, whereupon a motor-side inertial torque is reduced; and c. if in step a. the said necessity is determined, a second control command is issued by means of the control unit (3), whereupon a necessary adjusting force (9) is provided for a necessary duration to transfer the transmission at the wrap-around gear (2) to the underdrive, wherein step b. is performed before or during step c. the control unit (3) determines the necessity when: - an emergency deceleration is carried out; - such a high torque opposing the inertial torque is applied that a maximum design holding pressure (14) is to be maintained to prevent slippage of the wrapping element (15); and - a torque of such high frequency and high amplitude that changes direction is applied that a maximum holding pressure (14) is to be maintained to prevent slippage of the wrapping means (15), wherein the control unit (3) comprises an ABS system or is connected to an ABS system for communication purposes and the ABS system detects the output torque and / or provides the relevant control data, characterized by , that in step b. the motor-side inertia-related torque is reduced by the control unit (3) causing a torque opposite to the inertia-related torque to be applied to the drive machine which is an electric drive machine (7,8). [2] Method according to claim 1, wherein in step b. the drive train (1) further comprises at least one disconnect coupling (10,11) between the wrap-around gear (2) and at least one of the drive motors (6,7): at least one of the disconnect couplings (10,11) is opened, wherein the one between the wrapping gear (2) and the drive motor which is an internal combustion engine (6), The arranged disconnect coupling (10,11) is opened. [3] Method according to claim 1 or claim 2, wherein step b. is completed before the start of step c. wherein the wrapping gear (2) and a further provided disconnect clutch (10,11) are hydraulically actuated, wherein the wrap-around transmission (2) and the hydraulically actuated disconnect clutch (10,11) are supplied from a common supply system (12). [4] Method according to any of the preceding claims, wherein the inertia-induced torque is determined by the control unit (3) by: - the rotational acceleration of the motor side (4) is recorded; - the torque of the motor side (4) is detected; and / or - corresponding data from a motor control (13) of at least one of the drive machines (6,7) can be obtained. [5] Method according to one of the preceding claims, wherein an electric drive motor (8) for torque transmission is permanently connected to the wrapping gear (2), wherein a torque opposing the inertia-induced torque is applied to the permanently connected electric drive motor (8). [6] Powertrain (1) comprising at least the following components: - a control unit (3) for setting an operating state of the drive train (1); - a wrap-around transmission (2) with a motor side (4) and an output side (5); and - at least one drive motor (6,7,8), wherein the drive train (1) is configured by means of the control unit (3) to carry out the method according to one of the preceding claims, wherein at least one disconnect coupling (10,11) is provided between the wrap-around transmission (2) and at least one of the drive motors (6,7). [7] motor vehicle (16), comprising a drive train (1) according to claim 6 and at least one drive wheel (17,18), wherein the motor vehicle (16) can be driven by means of at least one of the drive motors (6,7,8) via the at least one drive wheel (17,18).

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