DE102016202733B4 - Transmission arrangement with push-down reduction in motor-driven vehicles - Google Patents

Abstract

Transmission arrangement with push-down for motor vehicles with an internal combustion engine and a gearbox, the drive shaft of the engine is substantially uninterrupted by a dual clutch with two gear trains mutually connectable and the even gears of the gearbox through the first gear train and the odd gears through the second gear train can be realized and both transmission lines act on the drive wheels of the vehicle, wherein when the vehicle is decelerated, the firing of the internal combustion engine is interrupted, so that it is dragged through the transmission essentially by the kinetic energy of the vehicle and during the deceleration process an automatic downshift of the gears takes place, characterized in that the transmission control is adapted to skip at least two speeds when shifting back from an engaged gear (G5) and when Shift to lower gear (G2) operates the clutch associated with the lower gear (G2) in the slip (SB) so that the engine speed (nMot) approximates a given asynchronous rotational speed (nAsync) and that it decreases the engine speed (nMot) below a predetermined positive distance of engine speed (nMot) to idle speed (nLL) opens the clutch associated with the lower gear (G2).

Description

The invention relates to a transmission arrangement with push-down for a motor-driven vehicle according to the preamble of claim 1.

Gear arrangements of the aforementioned type are commonly referred to as dual-clutch transmission and consist in principle of two automated part transmissions, each with a clutch. One partial transmission realizes the even gears, the other partial transmission the odd gears. From the wheelset ago the sub-transmission correspond in principle to a manual transmission, the sub-transmission to work on a common transmission output.

With respect to the gear change decides an electronic transmission control according to a shift program about which gear is to be engaged. The gear selection is dependent on the speed or the speed and the request of the driver via the pedals. The transmission control realizes the switching operations by controlling corresponding actuators, which then actuates the partial transmissions and clutches electromechanically or hydraulically.

When changing gear, the gear to be geared is engaged before shifting in the load-free branch, which is referred to as gear selection. In the next step, the clutch of the sub-transmission, which is assigned to the preselected gear and the clutch of the previously loaded gear opens at the same time, so that there is an uninterrupted moment transition from one to the other clutch. By means of the transmission control coordinated by grinding the two clutches, the engine speed is adapted to the new gear ratio. A dual-clutch transmission is switched substantially without traction interruption. In order to avoid a noticeable jerk during switching operations, the duration of the switching phase is made dependent on the speed difference, it is a few hundredths to tenths of a second.

A dual-clutch transmission, however, can be switched from a straight to an odd gear or from an odd gear to a straight gear in both upshifting and downshifting without traction interruption. If the speed and the acceleration or deceleration request of the driver, which is detected via the pedal position, skipping gears, the controller must therefore select depending on the situation a temporary support gear from the other sub-transmission, so the transmission can not skip a gear.

Because of the above-noted need for sequential switching through dual clutch transmissions, in the present state of the art, downshifts in the non-fired overrun mode of the vehicle (i.e., vehicle towing the vehicle engine) are performed as single-step downshifts only. The engine is always brought synchronously to the target speed of the target shaft or the target gear. For consumption reasons, it is desirable to carry out the maximum number of push-downshifts to the smallest possible gear to keep the engine as long as possible in the overrun cut-off.

In many cases, the push downshift, especially in transmissions with very short ratios, it is very common that from a certain negative acceleration of the vehicle, the downshifts can no longer be performed completely. As a result, the circuit must be canceled, or the clutches are opened. The internal combustion engine must then be brought into fired operation so as not to pull the engine below its idling speed. The engine must therefore burn and run on the idle controller (LL Governor), which consumes fuel.

The problem of abortion of the downshift is due to the fact that a very large number of circuits have to be executed within a small speed range and thus in a very short time. However, since the thrust-downshifts all last approximately the same length in the minimum and the distances of the circuits are getting smaller towards low gears, the time for the full thrust-downshift is often too short.

To allow the skipping of individual gear steps was with the DE 199 52 535 B4 proposed a power shift transmission, which has a clutch in addition to several gearshift clutches. However, such power shift transmission are complex and therefore expensive.

Furthermore, from the US Pat. No. 6,090,008 an automatic transmission of a motor vehicle with a control device for performing downshifts at zero load operating states known.

From the foregoing, it is an object of the invention to provide a push-down shift for a dual-clutch transmission, which allows a gear downshift over at least two gear stages away to perform directly.

The problem is solved by the features of claim 1 advantageous embodiments are disclosed in the dependent claims.

To solve the problem, the transmission control is designed so that it skips at least two gears when switching back from an engaged gear and when switching to the lower gear, the clutch is associated with the lower gear in the slip operates so that the engine speed of a given asynchronous -Speed, which is higher than the idling speed, approximately corresponds and that when the engine speed falls below a predetermined positive distance of the engine speed to idle speed, the clutch which is assigned to the lower gear opens. By the transmission control according to the invention is advantageously achieved that the non-fired overrun operation of the engine can be maintained as close to the vehicle standstill, which allows a significant fuel economy and brings by eliminating multiple speed changes haptic and acoustic comfort benefits.

Further, the transmission control is advantageously designed to perform the slip operation so that the engine is pulled up to the asynchronous speed or brought to the asynchronous speed by torque or speed control and is maintained substantially at this asynchronous speed until the asynchronous speed is substantially one of the Vehicle speed dependent speed value of the synchronous speed curve of the lower gear corresponds and that then completely closes the clutch.

The term synchronous speed curve of a gear while the speed curve is understood, which results when the gear is engaged and the vehicle passes through the permissible speed range for the gear. Each gear thus has its own, dependent on the Fahrzuggeschwindigkeit synchronous speed curve.

A further advantageous embodiment of the transmission control provides that this, after the clutch of the lower gear is opened, the control of the engine speed passes to the idle control of the engine control. This active transfer is particularly advantageous when transmission control and engine control are separate systems that communicate with each other via a communication interface. Of course, it is also possible to keep the idle controller active in the engine control during the push-down, so that it automatically takes over the idle control when the engine speed drops to idle speed level.

Further, it is advantageous for the design of the transmission control that it retains the engaged before the push-down gear selected as a passive gear in the load-free partial transmission during the push downshift. This makes it possible, when the driver requests a positive acceleration by corresponding pedal actuation, that the transmission control can switch immediately to the partial transmission with the engaged higher gear without interruption. In an advantageous continuation of this idea can be provided to design the transmission control so that it initially preselected the engaged before the push-down gear as passive gear in the load-free partial transmission during the push downshift and the current engine speed vehicle speed related cyclically with the dependent on the vehicle speed of the synchronous speed of the in the same partial transmission realized next smaller gear compares and preselects the next smaller gear realized as the passive gear in an approximate match in the same sub-transmission. This ensures that when requesting a positive acceleration sufficient torque is available at the drive wheels.

Information about the current engine speed, the current speed, the current position of at least the accelerator pedal, as well as about the actuation of the vehicle brake in the vehicle control already exists for the control of today's common motor vehicles. It is therefore advantageous to design the transmission control so that it uses this information. Alternatively, there is the possibility that the transmission control itself gains this information by interrogating sensor values and their evaluation. Such sensors are usually required to cope with a variety of control tasks in the motor vehicle and already exist.

If the idling speed is varied depending on environmental conditions such as ambient temperature, ambient pressure, etc. of the engine control, it is necessary to take over the currently valid idle speed of the engine control. If, however, it is a fixed idle speed, this can be stored in the access of the transmission control.

In a further advantageous embodiment, the transmission control is designed such that these are the idle speed and the asynchronous speed, which are held as memory values in the access of the transmission control, each with in their access memory values of intervals or distance ranges of the idle speed of the current engine speed and the Asynchrondrehzahl of the current engine speed compares and the Transmission control depending on the result of this comparison controls the clutches. In practice, a match with a certain speed difference can not be determined exactly but only if the distance of the idle speed of the current engine speed and the Asynchrondrehzahl of the current engine speed in a specific stored in the transmission control storage technology area.

To initiate the push downshift, the transmission control is advantageously designed to initiate the push downshift upon deceleration of the vehicle and uncontrolled engine operation, at a given distance or range of actual engine speed (nMot) from idle speed (nLL). In this way it can be achieved that the push downshift takes place in accordance with the situation.

Further, it is advantageous to design the transmission control so that it cyclically compares the engine speed with the Asynchrondrehzahl after triggering the push-down and that it opens at a positive deviation of the engine speed of the Asynchrondrehzahl the torque transmitting clutch and closes at a negative deviation. It can be provided that the opening and closing of the torque-transmitting coupling takes place in the slip region of the torque-transmitting coupling, so that the opening and closing only changes the degree of slippage.

The transmission control is also advantageously designed so that it cyclically compares the current engine speed with the speed dependent on the vehicle speed values of the synchronous speed curve of the engaged gear and then when a match of the current engine speed with a given by the vehicle speed speed value of the synchronous speed curve within predetermined limits is given, the torque-transmitting coupling completely closes. In this way it is achieved that the slip operation of the torque-transmitting coupling is terminated as early as possible.

In order to maintain the non-fired overrun of the engine as long as possible, it is further advantageous to design the transmission control to cyclically compare the current engine speed with the idle speed of the engine and then, if there is a match within predetermined limits, transmit the torque Clutch completely opens.

It should be noted at this point that the above-mentioned functional units such as engine control or transmission control can be formed by means of program routines that are implemented on arithmetic units. This is common in many areas today. Particularly in motor vehicles, computer-assisted control devices and data transmission means are usually available, which, in addition to many other control and regulating tasks, can take over the mapping of the functional units described above and their interaction. For the control or regulation necessary parameters, such. As current speed information, current speed information or current pedal positions are usually detected by sensors, of which there are a variety in today's conventional motor vehicles. The output information of the sensors are used for a wide variety of control tasks. Computer-aided control devices of the aforementioned type are generally known, so that unnecessary further explanations for this purpose.

Further embodiments and advantages of the invention will be explained in more detail with reference to the drawing. Show it:

1 a perspective view of a push-down according to the prior art; and

2 a perspective view of a push-down according to the invention.

For a better understanding of the thrust reverser according to the invention, it first appears necessary to explain the conditions in a previously known in the prior art thrust downshift. For this purpose, rotational speeds n are plotted against the vehicle speed v in a schematic diagram which is not to scale. In the illustration, the vehicle speed decreases from left to right until vehicle standstill at v = 0. Shown is on the one hand the course of the engine speed nMot and on the other hand, the synchronous speed curves of the individual gears as a function of the vehicle speed v. In this case, the transmission follows the synchronous speed curve nSync2 in the second gear, the synchronous rotational speed curve nSync3 in the third gear, the synchronous rotational speed curve nSync4 in the fourth gear and the synchronous rotational speed curve nSync5 in the fifth gear. The above-mentioned synchronous speed profiles are stored technically in the access of the transmission control. Next, the engine idle speed nLL is plotted.

It is for illustration in 1 assume that the driver brakes the vehicle so that the vehicle speed decreases. It is also assumed that the gearbox designed as a dual-clutch transmission of the Vehicle is in fifth gear G5, so that the course of the engine speed nMot corresponds to the vehicle speed dependent synchronous speed curve nSync5. Since the vehicle negatively accelerates according to the driver's request, the engine is not fired (pushing operation) for reasons of fuel economy and utilization of the engine brake, so that the braking torque of the engine and possibly the vehicle brakes slow the vehicle and thus the engine speed nMot along the vehicle speed pull down the dependent fifth-speed synchronous speed curve nSync5. To prevent the engine speed from being drawn below the idle speed nLL, as the engine speed nMot approaches the idle speed nLL, a downshift must be made from the fifth gear G5 to the next lower gear to rev up the engine speed through the kinetic energy of the vehicle or the engine speed move up via a positive torque or speed intervention. The change from the fifth gear G5 to the fourth gear G4 is initiated programmatically at the first shift point S1, the fourth gear G4 is engaged as a target gear and the torque at the first engagement point K1 is taken over by the clutch associated with the fourth gear G4, so that from this point on Engine speed nMot up to the synchronous speed curve of the fourth gear nSync4 is pulled up. If the synchronous speed curve of the fourth gear nSync4 is reached, the engine speed nMot decreases in accordance with the synchronous speed curve of the fourth gear nSync4 with decreasing vehicle speed v. Here, too, the engine speed nMot approaches the idling speed nLL again with further negative acceleration, so that another gear change is pending. The renewed gear change, this time from the fourth gear G4 to the third gear G3 is also initiated programmatically at the second shift point S2, the third gear G3 is engaged as target gear and the torque at the second engagement point K2 is taken over by the third gear G3 associated clutch, so from this point to the engine speed nMot up to the synchronous speed curve of the third gear nSync3 is pulled up. When the synchronous speed curve of the third speed nSync3 has been reached, the engine speed nMot corresponding to the synchronous speed curve of the third speed nSync3 decreases as the vehicle speed v decreases and in turn approaches the idle speed nLL. Since it is necessary to wait for the gear change from the third gear G3 to the second gear G2 until the speed of the synchronous rotational speed curve nSync2 of the second gear G2 which is dependent on the vehicle speed is low enough, the time for a further gear change is no longer sufficient. For this reason, there is no gear change to the second gear G2, the third gear G3 associated clutch of the dual clutch transmission opens, the idle controller of the engine control takes over, the engine is fired and the engine speed control keeps its speed to idle speed nLL. The process referred to above as pushing downshift therefore has to be prematurely terminated, which results in increased fuel consumption because the engine must be operated again at idling speed nLL after termination of the overrun fuel cutoff. In addition, any high engine drag caused by the kinetic energy of the vehicle and any clutch change (change in gear ratio) results in an increase in the thrust torque on the wheels operatively connected to the transmission, which manifests itself after each gear change in a perceptible change in wheel torque (jerk) and every engine hump causes acoustically noticeable increase in noise due to the increase in speed. Both have a comfort-reducing effect. Double-clutch transmissions with a push-down mechanism according to the prior art described above have, in terms of push-down, significant fuel consumption and comfort disadvantages.

Push downshifts across multiple gears are in stop operations z. As at traffic lights very often given, resulting in a significant fuel-saving potential results when the burning of the engine can be delayed as far as possible. For this purpose, it is provided that the push-down circuit is not executed sequentially but over at least two switching stages, wherein the two switching stages are skipped. This skipping of at least two switching stages is due to the fact that in dual-clutch transmissions two automated partial transmissions each with a clutch are used, the odd gears G1, G3, G5, etc. the one partial transmission and the even gears G2, G4, G6, etc. are assigned to the other sub-transmission. A gear change without Schubkraftunterbrechung is therefore only possible if the currently engaged gear is associated with a first of the two sub-transmission and the target gear to be engaged the other sub-transmission. 2 shows such asynchronous push-down according to the invention in the form of a diagrammatic representation by way of example. In this case as well, rotational speeds n are plotted against the vehicle speed v in a not to scale schematic diagram. In the illustration, the vehicle speed decreases from left to right until vehicle standstill at v = 0. Shown is on the one hand the course of the engine speed nMot and on the other hand, the synchronous speed curves of the gears G2 to G5 as a function of the vehicle speed v. In this case, the transmission in the second gear G2 follows the synchronous speed curve nSync2, in the third gear G3 the synchronous rotational speed curve nSync3, in the fourth gear G4 the synchronous rotational speed curve nSync3. Speed curve nSync4 and fifth gear G5 the synchronous speed curve nSync5. The above-mentioned synchronous speed profiles are stored technically in the access of the transmission control. Furthermore, the engine idling speed nLL is plotted, as well as an asynchronous speed nAsync, which is higher by an offset than the idling speed nLL. The idle speed nLL is provided by the engine control and stored stored in the access of the transmission control, the asynchronous speed nAsync is also stored in the access of the transmission control. The vehicle speed v is detected by means of a sensor.

Also for the representation in 2 it is assumed that the driver's request decelerates the vehicle, so that the vehicle speed is reduced. It is further assumed that the transmission of the vehicle designed as a dual-clutch transmission is in the fifth gear G5, so that the engine rotational speed nMot corresponds to the synchronous rotational speed curve nSync5. Since the vehicle negatively accelerates according to the driver's request, the engine is not fueled (overrun) for reasons of fuel economy and utilization of the engine brake, so that the braking torque of the engine and possibly the vehicle brakes slow the vehicle and thus the engine speed nMot along the synchronous speed curve of the fifth Pull Ganges nSync5 down with decreasing vehicle speed. To prevent the engine speed from being pulled below the idle speed nLL, as the current engine speed nMot approaches idle speed nLL, a downshift from fifth gear G5 to a lower gear must be made to bring the engine up to a higher speed Speeds far enough away from the idle speed nLL.

For this purpose, the transmission control is adapted to cyclically compare the current engine speed nMot with the idle speed nLL, and when the comparison result is in a range defined in the transmission control, this is defined as reaching an asynchronous shift point AS1. The downshift is then carried out so that at the asynchronous switching point AS1 programmatically the second gear G2 is engaged as a target gear by the transmission control and the torque at the asynchronous Einkluppelpunkt AK1 is taken over by the second gear G2 associated clutch. The asynchronous Einkluppelpunkt AK1 is a time defined by the dome time period after the asynchronous switching point AS1, the dome time is given by the structural design of the transmission unchangeable period of time. After engagement at the asynchronous Einkluppelpunkt AK1 the engine speed of the unfired engine in the slip SB is towed up, while the second gear G2 associated clutch is controlled by the transmission control so that it is operated in the slip SB even when reaching an asynchronous speed n Async. The achievement of the asynchronous speed n Async is determined by the transmission control on the basis of a cyclic comparison of the current engine speed n Mot with the asynchronous speed n Async. After reaching the asynchronous speed n Async controls the transmission control by further cyclical comparison of the current engine speed nMot with the asynchronous speed n Async the torque-transmitting clutch so that the asynchronous speed n Async is essentially maintained. To this end, the transmission control increases the slip of the torque transmitting clutch associated with the second gear G2 when the engine speed nMot exceeds the asynchronous speed nAsync by slightly opening the clutch and reduces the slip when the engine speed nMot is below the asynchronous speed nAsync by slightly closing the clutch. In practice, the engine speed nMot thus oscillates around the asynchronous speed nAsync. The oscillation about the asynchronous speed nAsync is maintained until the synchronous speed curve nSync2 of the second gear G2 is reached, this determines the transmission control by the current engine speed nMot with given by the current vehicle speed speeds of the synchronous speed curve nSync2 the second gear G2 cyclically compares. If the current engine speed nMot reaches the synchronous speed curve nSync2 of the second gear G2, d. H. If, given the current vehicle speed, the engine speed nMot coincides with the speed value of the synchronous speed curve nSync2 of the second gear G2 given for this vehicle speed within predetermined limits, the clutch assigned to the second gear G2 is completely closed. Thus, the engine speed nMot moves due to the further deceleration of the vehicle together with the synchronous speed curve of the second gear nSync2 toward idle speed nLL. Now, the transmission controller cyclically compares the current engine speed nMot with the idle speed and opens the clutch associated with the second gear G2 at a given positive engine speed rotational speed nMot from the idle speed nLL and passes to the engine controller which fires the engine and controls the idle speed nLL ,

During the push downshift, the transmission control passes the fifth gear G5p passively; H. the fifth gear G5p remains preselected to accelerate in the event of a positive acceleration request by the driver with this gear. Alternatively, of course, there is the possibility that the transmission control cyclically compares the current engine speed nMot with the given by the current vehicle speed speed of the synchronous speed curve nSync3 of the third gear G3 and then when the engine speed nMot this speed substantially corresponds to the gear selector in the unloaded partial transmission from fifth passive gear G5p switches to the passive third gear G3p to provide sufficient torque at the drive wheels at a positive acceleration request by the driver can.

Of course, the transmission control described above, the operation of which is described with reference to a downshift from the fifth gear G5 in the second gear G2, perform any downshifts of the type described. For example, downshifts from seventh gear to fourth gear, from sixth gear to third gear from seventh gear to second gear, etc. are possible. It is essential that actual gear and target gear are not realized in the same sub-transmission.

Furthermore, several of the push-down circuits according to the invention can be arranged next to one another if, for example. As common in commercial vehicles, the number of available gears requires this.

As described in the above description in several places, during the implementation of the described gear shift in overrun torque or odor speed can take place by firing the engine, for example, to adjust the speed to reduce wear or to increase ride comfort. However, such phases of fired operation degrade the fuel balance and are to be minimized.

LIST OF REFERENCE NUMBERS

• nSync2

  Synchronous speed curve gear 2

  nSync3

  Synchronous speed curve gear 3

  nSync4

  Synchronous speed curve gear 4

  nSync5

  Synchronous speed curve gear 5

  G2

  second gear

  G3

  third gear

  G4

  fourth gear

  G5

  fifth gear

  S1

  first switching point

  S2

  second switching point

  K1

  first dome point

  K2

  second dome point

  AS

  Asynchronous switching point

  AK

  Asynchronkuppelpunkt

  nLL

  Idle speed

  Mot

  Engine speed

  G5p

  fifth gear passive

  g3p

  third gear passive

  nAsync

  asynchronous speed

  SB

  slip operation

Claims (12)

Transmission arrangement with push-down for motor vehicles with an internal combustion engine and a gearbox, the drive shaft of the engine is substantially uninterrupted by a double clutch with two gear trains mutually connectable and the even gears of the gearbox through the first gear train and the odd gears through the second gear train can be realized and both transmission lines act on the drive wheels of the vehicle, wherein when the vehicle is decelerated, the firing of the internal combustion engine is interrupted, so that it is dragged through the transmission essentially by the kinetic energy of the vehicle and during the deceleration process an automatic downshift of the gears takes place, characterized in that the transmission control is adapted to skip at least two speeds when shifting back from an engaged gear (G5) and when Shift to lower gear (G2) operates the clutch associated with the lower gear (G2) in the slip (SB) so that the engine speed (nMot) approximates a given asynchronous rotational speed (nAsync) and that it decreases the engine speed (nMot) below a predetermined positive distance of engine speed (nMot) to idle speed (nLL) opens the clutch associated with the lower gear (G2). Gear arrangement according to claim 1, characterized in that the transmission control is adapted to perform the slip operation such that the motor is pulled up to the asynchronous speed (nAsync) and maintained at substantially this asynchronous speed (nAsync) until the asynchronous speed (nAsync ) substantially corresponds to a speed dependent on the current vehicle speed of the synchronous speed curve (nSync2) of the lower gear (G2) and that then completely closes the clutch. Transmission arrangement according to claim 1, characterized in that the transmission control is designed so that, after the clutch of the lower gear (G2) is opened, the control of the engine speed (nMot) passes to the idle control of the engine control. Gear arrangement according to one of the preceding claims, characterized in that the transmission control is designed so that they during the push-down shift, the gear engaged before the push-down shift (G5) remains preselected as a passive gear (G5p) in the load-free partial transmission. Transmission arrangement according to one of the preceding claims, characterized in that the transmission control is designed so that it initially preselected during the push downshift before the thrust reverse gear (G5) as a passive gear (G5p) in the load-free partial transmission and at approximately coincidence of the current engine speed with a dependent on the current vehicle speed speed value of the synchronous speed curve (nSync3) of the implemented in the same partial transmission next smaller gear (G3) this next smaller gear (G3) as a passive gear (G3p) preselected. Transmission arrangement according to one of the preceding claims, characterized in that the transmission control is designed such that it contains the information about the current engine speed (nMot) and / or the current vehicle speed (v) and / or the pedal position and / or the currently valid idle speed of the engine control takes over or wins by querying sensors. Transmission arrangement according to one of the preceding claims, characterized in that the transmission control is designed so that it holds the idling speed (nLL) and the asynchronous speed (nAsync) stored as memory values in their access and respectively the distance of the idle speed (nLL) from the current engine speed (nMot) and the asynchronous speed (nAsync) of the current engine speed (nMot) cyclically compares with stored stored intervals or distance ranges and controls the clutches depending on the result of this comparison. Gear arrangement according to claim 7, characterized in that the transmission control is designed so that it initiates the deceleration switchback at deceleration of the vehicle and uncontrolled engine operation, at a predetermined distance or distance range of the current engine speed (nMot) of the idle speed (nLL). Transmission arrangement according to claim 7, characterized in that the transmission control is designed such that it compares the engine speed (nMot) cyclically with the Asynchrondrehzahl (nAsync) after triggering the push downshift and that they at a positive deviation of the engine speed (nMot) of the Asynchrondrehzahl ( nAsync) opens the torque-transmitting clutch and closes when there is a negative deviation. Gear arrangement according to claim 9, characterized in that the opening and closing of the torque-transmitting coupling takes place in the slip region of the torque-transmitting coupling. Gear arrangement according to claim 7, characterized in that the transmission control is designed such that it cyclically compares the current engine speed (nMot) with the speed dependent on the current vehicle speed of the speed stored in the transmission control held synchronous speed curve (nSYC2) of the engaged gear (G2) and then, when a match is given within predetermined limits, the torque transmitting clutch closes completely. Transmission arrangement according to claim 7, characterized in that the transmission control is adapted to cyclically compare the current engine speed (nMot) with the idle speed (nLL) of the engine and then, if a match is given within predetermined limits, the torque transmitting clutch fully opens.

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