EP1485642A2

EP1485642A2 - Twin-clutch transmission and method for performing a gear shift in a twin-clutch transmission

Info

Publication number: EP1485642A2
Application number: EP03711838A
Authority: EP
Inventors: Jürgen BENZ; Reinhard Berger; Lidvar Budal; Dietmar Lang; Wolfgang Niessen; Alexander Schweizer; Brad Shellhammer; Jeremy Whitmer
Original assignee: LuK Lamellen und Kupplungsbau Beteiligungs KG; LuK Lamellen und Kupplungsbau GmbH
Current assignee: Schaeffler Buehl Verwaltungs GmbH; LuK Lamellen und Kupplungsbau GmbH
Priority date: 2002-03-07
Filing date: 2003-02-28
Publication date: 2004-12-15
Also published as: WO2003074907A2; WO2003074907A3; AU2003218617A1; DE10308689A1; FR2837256A1

Abstract

The invention relates to a twin-clutch transmission and a method for performing a gear shift in a twin-clutch transmission having at least two transmission input shafts. According to the invention, the clutches associated with the transmission input shafts are torque-controlled depending on the load condition of the twin-clutch transmission and/or the shift-mode.

Description

Dual clutch transmission and method for performing a shift in a dual clutch transmission

The invention relates to a double clutch transmission and a method for performing a shift in a double clutch transmission with at least two transmission input shafts.

Parallel shift transmissions or double clutch transmissions and a method for performing a shift in a double clutch transmission are known from vehicle technology. A shift can be carried out without interrupting the tractive force as long as the target gear and the current gear or the initial gear are in engagement with different transmission input shafts. In the event that one gear or several gears are to be skipped in a shift, so that the target gear and the starting gear are in engagement with the same transmission input shaft, i.e. the fact that the target gear is not the next higher or lower gear cannot be realized with the known method of a shift-free interruption, because no change of the transmitted input shaft is carried out with this shift. This results in less comfort for the driver with this circuit.

Accordingly, the object of the invention is to propose a double clutch transmission and a method of the type mentioned in the introduction in order to carry out shifting operations that are as comfortable as possible without interrupting the tractive force.

The object of the invention is achieved by an inventive method for performing a shift in a double clutch transmission with at least two

Gearbox input shafts solved, in which a torque control is carried out on the clutches assigned to the gearbox input shafts as a function of the load condition of the double clutch gearbox and / or the type of shifting.

In this way, depending on the state in the transmission, for. B. tensile or shear load, and the type of circuit, for. B. upshift or downshift, the torque in the drive train is controlled by coordinated actions of the two clutches and the engine such that preferably suppresses drive train vibrations be and a maximum driving comfort is made possible. The torque control is preferably divided into several phases.

As part of a further development, a general shift strategy is proposed, in particular for shifts in which the starting gear and the target gear are assigned to different transmission input shafts.

In the method according to the invention it can be provided that after a gear change signal in a first phase (phase 1), the still torque-transmitting clutch of the first transmission input shaft, which is assigned to the starting gear, is opened and that a check is carried out at the end of the first phase (phase 1), whether the drive train is in overrun or pull operation.

Thereafter, during a second phase (phase 2) with a slipping clutch of the first transmission input shaft, a slip reserve can be built up by keeping the clutch torque constant and / or by appropriately increasing the engine torque as a function of the driver's desired torque, the engine speed being adjusted to a target speed. The target speed can, for. B. in train operation by the maximum of the starting gear speed and the target gear speed plus the slip reserve and in overrun mode by the minimum of the starting gear speed and the target gear speed minus the slip reserve. It is also possible that if the engine torque is not sufficient to reach the target speed, the clutch torque of the torque-transmitting clutch is additionally reduced.

According to a further development, in a third phase (phase 3) for cross-fading, the torque on the torque-transmitting clutch can be reduced to the value 0 using a predetermined ramp function or the like, while at the same time the torque on the clutch of the target gear is increased to the slip limit. Thereafter, as part of a further embodiment, the engine speed can be coordinated with the target speed by increasing (in overrun mode) or reducing (in train mode) the engine torque depending on the driver's desired torque during a next phase (phase 5). The target engine speed can be determined, for example, in train operation by the target gear speed and the slip reserve and in overrun mode by the target gear speed and the slip reserve. Finally, the shift can be terminated in a further phase (phase 6), in which a slip-stick transition is realized by a corresponding reduction or increase in the engine torque as a function of the driver's desired torque and / or by closing the clutch of the target gear in order to ensure a smooth transition To achieve transition, the engine torque is preferably reduced in train operation and increased in overrun.

It is possible that in the proposed method the phases mentioned are supplemented by further phases or that phases are omitted. The phases can also be combined with one another as desired.

Furthermore, the object of the present invention is proposed by a method according to the invention for performing a shift in a dual clutch transmission with at least two transmission input shafts, in which a shift is made from the starting gear into an intermediate gear which is in engagement with the other, second transmission input shaft. This intermediate gear can then transmit a moment to the output, while the initial gear is switched to the target gear on the first transmission input shaft. In this way, this special shifting can also be carried out comfortably without interrupting the tractive force.

In particular, four different shift types are taken into account in the method according to the invention, namely the train upshifts, the push upshifts, the train downshifts and the push downshifts. According to a development of the invention, several different phases can also be used in the torque control on the clutches of the two transmission input shafts in this embodiment in order to achieve a comfortable cross-fading in the individual switching phases. It is possible for phases to be omitted or added, and for the phases to be combined with one another as desired. The loss of comfort known from the prior art can be avoided by using the shift strategy according to the invention. In a first phase (phase 1) z. B. the torque transmitting clutch of the first transmission input shaft is opened. At the end of the first phase, it is checked whether the drive train is in overrun or pull operation.

A second phase (phase 2 ') of the method according to the invention can provide that when the clutch of the first transmission input shaft slips, a slip reserve is preferably built up by keeping the clutch torque constant and / or by appropriately increasing the engine torque as a function of the driver's desired torque, the engine speed being at a desired speed is adjusted. The target speed can be determined, for example, in train operation or operation by the maximum of the starting gear speed and the intermediate gear speed plus the slip reserve, the starting gear speed the speed of the first transmission input shaft when the starting gear is engaged and the intermediate gear speed the speed of the second transmission input shaft when the intermediate gear is engaged. In overrun mode or state, the target speed z. B. by the minimum of

Starting gear speed and the intermediate gear speed minus the slip reserve can be determined.

It is conceivable that in the context of the second phase (phase 2 '), if the engine torque is not sufficient to reach the target speed, the clutch torque of the torque-transmitting clutch, for. B. the first transmission input shaft is reduced.

In a third phase (phase 3), the clutch torque of the starting gear or the first transmission input shaft can be reduced to the value 0 with a predetermined ramp function, while z. B. at the same time the clutch torque of the clutch of the intermediate gear or the second transmission input shaft is increased to the slip limit. The clutch torque can preferably be reduced linearly via a constant ramp function or the like.

As part of a fourth phase (phase 4) of the method according to the invention, it can be provided that the starting gear is removed and the target gear is engaged when changing gear. According to a development of the invention, the second phase (phase 2 ') can be repeated after the fourth phase (phase 4), the The target speed in train operation is determined by the maximum of the intermediate gear speed and the target gear speed plus the slip reserve. In overrun mode, the target speed can be determined by the minimum of the intermediate gear speed and the target gear speed minus the slip reserve. The target gear speed is the speed of the first transmission input shaft when the target gear is engaged.

After the slip phase has been built up by repeating the second phase (phase 2 '), the third phase (phase 3) can be repeated for cross-fading, the clutch torque on the clutch of the intermediate gear or the second transmission input shaft having a predetermined ramp function to the value 0 is reduced while z. B. at the same time the clutch torque of the clutch of the target gear or the second transmission input shaft is increased to the slip limit.

For engine synchronization, it can be provided in a fifth phase (phase 5) that by increasing or reducing the engine torque as a function of the driver's desired torque, the engine speed is coordinated with the target speed, the target speed in train operation being determined by the target gear speed and the slip reserve , In overrun mode, the target speed is determined by the target gear speed minus the slip reserve.

In the context of a sixth phase (phase 6) of the method according to the invention it can be provided, for example, that a slip-grip transition is realized by a corresponding reduction in the engine torque as a function of the driver's desired torque and / or by closing the clutch of the target gear in order to ensure a smooth transition reach and finish the circuit.

In the context of an advantageous embodiment of the present invention, it can be provided according to a further variant of the method according to the invention that a variable torque replenishment takes place on the clutches of the transmission input shafts, in particular during downshifts in train operation. In gearshifts in train operation, the speed of the motor should be above the speed of the first transmission input shaft with which the target gear is engaged in order to achieve a cross-fade or overlap with positive abrasion moments. This speed adjustment can be carried out according to the invention by a positive motor torque intervention in order to To reach the target speed. The positive engine torque intervention can preferably be implemented in the case of part-load circuits.

A further variant of the method according to the invention can provide that, for example, at the beginning of the circuit for torque control on the clutches of the transmission input shafts, a load and speed-dependent filling torque or level is determined and changed for speed adjustment during the switching, so that the filling torque on the clutches during the Speed adjustment can be set variably. Either the filling torque or level on the drive or on the output during a shift can be controlled. For example, that

Fill torque level on the output must be constant so that the driver perceives a constant output torque during the speed adjustment. If the fill torque level at the drive is constant, the speed can be adjusted with a constant speed change of the motor.

In the method according to the invention, the filling torque at the output torque can advantageously be variably set by coupling the initial gear or the first transmission input shaft. This results in advantages in terms of switching time and spontaneity, particularly in the case of kickdown downshifts.

For example, the engine interventions can be carried out at low load in order to enable the engine to be revved up quickly. By opening the clutch at the start of the downshift, the relatively slow approach to the slip limit can be omitted if there is sufficient load. This makes train downshifts even more spontaneous. The speed adjustment can z. B. Orientate to the target speed of the new gear. In this way, the driver does not notice the engagement of an intermediate gear on the inactive sub-transmission.

According to a development of the present invention, it can be provided that the target gear is used as the basis for determining the level of the filling torque or the filling torque. The speed adjustment can always be based on the target gear speed and not on the intermediate gear speed. In this way driving comfort is increased so that the driver does not notice the engagement of the intermediate gear on the inactive sub-transmission.

In the context of an embodiment of the invention it can be provided that the level of the filling torque is first reduced and then kept constant for a predetermined time before it is correspondingly rebuilt at the end of the speed adjustment. When the target speed is reached, the filling level of the slipping clutch, for example of the first transmission input shaft, is increased again to the drive torque. This allows the speed to be kept constant at the target gear speed. This is particularly important if the target gear is not yet engaged in the partial transmission.

In this variant of the method according to the invention, a continuous calculation of the filling level can be carried out. This can preferably be divided into three sections. In a first section, the filling level z. B. degraded linearly. Thereafter, the filling level can be kept at a predetermined level during a second section, and then during a third section at the end of the speed adjustment z. B. speed and / or slip dependent.

According to a development of the invention is for a circuit, the sum of the clutch torques ^ ^^ equal to the Auffüllmoment MF II- _Ü _Ü The Auffüllmoment MF II can be determined by the following equation:

M _mι = M _{driver's wish} • level of filling torque

wherein _F _h a r _e rwun _sch is the driver's requested torque. Here, the M is Auffüllmoment _mι relative to the driver's desired torque M _F a determined rerwunsch _h, whereby changes in the driver's desired torque M _F ahrerwunsch be taken into account.

Furthermore, the object of the invention is achieved by a double clutch transmission. The dual clutch transmission according to the invention with at least two transmission input shafts can preferably be used to carry out the methods described above. According to the invention, the double clutch transmission has at least one device for torque control as a function of the load condition of the double clutch transmission and / or the type of shifting on the clutches assigned to the transmission input shafts.

Further advantages and advantageous configurations result from the subclaims and the drawings described below. Show it:

FIG. 1 shows a flow diagram of a first exemplary embodiment of a method according to the invention;

Figure 2 curves of engine speed, engine torque and

Coupling torque depending on the respective switching phases for four different circuits according to Figure 1;

FIG. 3 shows a flow diagram of a second exemplary embodiment of the method according to the invention;

FIG. 4 curves of the engine speed, the engine torque, the clutch torque and the respective gear for three different upshifts according to FIG. 3;

FIG. 5 curves of the engine speed, the engine torque, the clutch torque and the respective gear for three different thrust upshifts according to FIG. 3;

FIG. 6 curves of the engine speed, the engine torque, the clutch torque and the respective gear for three different train downshifts according to FIG. 3;

Figure 7 curves of engine speed, engine torque and

Coupling torque and the respective gear for three different thrust backshifts according to Figure 3; Figure 8 curves of different speeds and the clutch and the

Engine torque according to a second embodiment of the method according to the invention with a positive engine torque intervention in a double downshift via an intermediate gear;

FIG. 9 shows a schematic course of the filling torque level according to a third

Embodiment of the method according to the invention;

Figure 10 shows schematic curves of different speeds and the

Clutch torque and the engine torque in a downshift according to the third embodiment of the method according to the invention;

FIG. 11 shows schematic curves of different speeds and the clutch torque and the engine torque in a double downshift according to the third exemplary embodiment of the method according to the invention, the target gear having already been engaged;

FIG. 12 shows schematic profiles of different speeds, the clutch torque and the engine torque of a double downshift according to the third exemplary embodiment of the method according to the invention, the target gear not being engaged when the target speed has been reached; and

FIG. 13 shows schematic curves of different speeds, the clutch torque and the engine torque in a double downshift according to the third exemplary embodiment of the method according to the invention, the target speed being reached before the overlap on the intermediate gear.

FIG. 1 shows a flow chart of a first exemplary embodiment of the method according to the invention for performing a shift between two gears of different transmission input shafts in a double clutch transmission. The couplings of the Double clutch transmission controlled accordingly in order to enable a shift-free interruption.

After a gear change signal, a change is made in a first phase (phase 1) on the torque-transmitting clutch from the state of sticking to the state of slipping. For this purpose, the torque-transmitted clutch of the first transmission input shaft is brought into the slip state by linearly reducing the clutch torque. At the end of the phase, i.e. immediately before the start of the second phase (phase 2), a decision is made as to whether the drive train is in the pulling or pushing state. If there is no slip, the first phase (phase 1) is repeated. If there is slippage, it is checked whether the slippage on the transmitted clutch is positive or negative in order to determine whether there is a pulling or pushing operation. Train operation is with positive slip if the engine speed is greater than the speed of the transmission input shaft. If the engine speed is less than the speed of the transmission input shaft in the event of a negative slip, the overrun mode is present. Then the second phase (phase 2) begins.

During a second phase (phase 2) when the clutch of the first transmission input shaft slips, a slip reserve is maintained by keeping the clutch torque constant and / or by appropriately increasing the engine torque

Dependency of the driver's desired torque is built up, the engine speed being adjusted to a target speed. The target speed can, for. B. in train operation by the maximum of the starting gear speed and the target gear speed plus the slip reserve and in overrun by the minimum of the starting gear speed and the target gear speed minus the slip reserve. It is also possible that if the engine torque is not sufficient to reach the target speed, the clutch torque of the torque-transmitting clutch is additionally reduced.

In a third phase (phase 3) for cross-fading, the torque on the torque-transmitting clutch is reduced to the value 0 using a predetermined ramp function or the like, while at the same time the torque on the clutch of the target gear is increased to the slip limit.

In a further phase (phase 5), an increase (in overrun mode) or a reduction (in train mode) in the engine torque depending on the Driver's desired torque, the engine speed is coordinated with the target speed. The target engine speed can be determined, for example, in train operation by the target gear speed and the slip reserve and in overrun mode by the target gear speed and the slip reserve.

Finally, the shift is ended in a further phase (phase 6), in which a slip-stick transition is achieved by a corresponding reduction (in train operation) or increase (in overrun operation) as a function of the driver's desired torque and / or by closing the clutch of the target gear is realized in order to achieve a smooth transition. Then it is checked whether the clutch is stuck, if no this phase (phase 6) is repeated and if so the shift is complete.

The proposed control strategy is illustrated in FIG. 2 on the basis of various shift types, namely the train upshift, the push upshift, the train downshift and the push downshift. Three diagrams arranged one above the other are shown for each circuit type. The diagram shows the course of various variables during the respective switching over time or over the switching phases.

In the diagrams on the first line, the curve of the engine speed with a solid line I, the curve of the speed of the second transmission input shaft (assigned to the target gear) with the solid line A and the speed of the first transmission input shaft (assigned to the initial gear) with the solid line B for the different phases over time. The second line shows the current engine torque with a solid line and the driver's desired torque with a dashed line over time. The third line shows the torque transmitted by the second clutch with a solid line A and the torque transmitted by the first clutch with a solid line B over time.

Overall, knowledge of the slip limits for the clutch is crucial. In phase 2, the torque of the clutch still transmitting should be at the slip limit being held. In phase 3 the torque of the target gear is brought to the expected slip limit and in phase 5 it is kept at the slip limit.

FIG. 3 shows a flow diagram of a second exemplary embodiment of the method according to the invention for performing a shift between two gears of the same transmission input shaft in a double clutch transmission. The clutches of the dual clutch transmission are controlled accordingly by the method according to the invention, in order to enable a shift-free interruption in the traction force.

In a first phase (phase 1), the torque-transmitting clutch changes from the sticking state to the slipping state. For this purpose, the torque-transmitted clutch of the first transmission input shaft is brought into the slip state by linearly reducing the clutch torque. At the end of the phase, ie immediately before the start of the second phase (phase 2 '), a decision is made as to whether the drive train is in the pulling or pushing state. If there is no slip, the first phase (phase 1) is repeated. If there is slippage, it is checked whether the slippage on the transmitted clutch is positive or negative in order to determine whether there is a pulling or pushing operation. Train operation is with positive slip if the engine speed is greater than the speed of the transmission input shaft. If the engine speed is less than the speed of the transmission input shaft in the event of a negative slip, the overrun mode is present. Then the second phase (phase 2 ') begins.

In the second phase (phase 2 '), a so-called slip reserve is built up. For this purpose, the torque of the transmitting clutch can be kept constant or at the slip limit. The engine speed is brought to a target speed by suitably increasing or decreasing the engine torque with respect to the desired driver torque. If the engine torque is insufficient to reach the target speed within an acceptable time, the torque of the transmitting clutch can be reduced, for example. A distinction is made as to whether the train or the push operation is present. The target speed is the maximum of the starting gear speed and the intermediate gear speed when the intermediate gear is switched plus a hatch reserve. With a thrust shift into the intermediate gear, the target speed is defined by the minimum of the starting gear speed and the intermediate gear speed minus the slip reserve, the starting gear speed being the speed of the first transmission input shaft when the starting gear is engaged and the intermediate gear speed is the speed of the second transmission input shaft in the intermediate gear.

In a third phase (phase 3) the cross-fading is carried out. The torque of the transmitted clutch, which is assigned to the first gear input shaft engaged with the starting gear, is preferably determined via a constant ramp z. B. linearly reduced to the value 0, while at the same time the torque of the clutch of the intermediate gear is driven to the slip limit. The third phase (phase 3) is identical for train and push operations.

In a fourth phase (phase 4) the gear change is carried out from the starting gear to the intermediate gear, the starting gear being removed and the intermediate gear being engaged.

After the fourth phase (phase 4), the second phase (phase 2 ') will be repeated, a distinction also being made here between train operation and push operation. In train operation, the target speed is determined by the maximum of the intermediate gear speed and the target gear speed plus the slip reserve, and in overrun mode the target speed is determined by the minimum of the intermediate gear speed and the target gear speed minus the slip reserve. The target gear speed is the speed of the first transmission input shaft when the target gear is engaged.

After the build-up of the slip reserve by repeating the second phase (phase 2 '), the third phase (phase 3) can be repeated for cross-fading, the clutch torque of the intermediate gear, ie the second transmission input shaft, being reduced to the value 0 with a constant ramp function, while at the same time the clutch torque of the clutch of the target gear is driven to the slip limit.

In a fifth phase (phase 5) the motor synchronization is carried out. By appropriately increasing or decreasing the engine torque with respect to the Driver's desired torque, the engine speed can be brought to a desired target speed. If the engine torque is insufficiently large or small to reach the target speed within an acceptable time, z. B. in addition, the torque of the clutch of the target gear can be increased. The target speed for train shifts is determined by the target gear speed and the slip reserve. In overrun circuits, the target speed is determined by the target gear speed minus the slip reserve.

In a sixth phase (phase 6), the torque-transmitting clutch changes from the slip state to the sticking state. This is achieved by a suitable increase (in overrun mode) or decrease (in train mode) of the engine torque with respect to the driver's desired torque and / or by closing the clutch of the target gear or the first transmission input shaft until the clutch no longer slips. The slip-stick transition should be carried out with a smoothing in order to achieve a smooth transition and in this way to avoid jerking movements when switching. The sixth phase (phase 6) can be repeated until the clutch sticks and the target gear is engaged in order to end the shifting by the method according to the invention.

FIGS. 4 to 7 each show 12 diagrams in three columns, the diagrams in each column being assigned to a specific circuit. In the diagrams on the first line, the curve of the engine speed with a solid line I, the curve of the speed of the second transmission input shaft (assigned to target gear) with the solid line II and the speed of the first transmission input shaft (assigned to the initial gear) with dashed line for different gear changes represented the time. The second line shows the current engine torque with a solid line and the driver's desired torque with a dashed line over time. The third line shows the torque transmitted by the second clutch with a solid line A and the torque transmitted by the first clutch with a dashed line B over time. The fourth line shows the gears of the transmission input shafts in each case over the phases of the shift, the solid line B identifying the engaged gears of the first transmission input shaft and the dashed line A identifying the engaged gears of the second transmission input shaft. So the first clutch is the first Gearbox input shaft and the second clutch assigned to the second gearbox input shaft. These aforementioned designations apply to FIGS. 4 to 7.

In Figure 4 are diagrams for various train upshifts. The left column of FIG. 4 shows the diagrams which result from a 2- (1) -4 train upshift, the intermediate gear being given in brackets. In this case, the gear ratio of the intermediate gear is greater than the gear ratio of the initial gear. The middle column in Figure 4 shows a 2- (3) -4 train upshift, the gear ratio of the intermediate gear being between the gear ratio of the starting gear and the target gear. The right column in Figure 4 shows a 2- (5) -4 train upshift, the gear ratio of the intermediate gear being smaller than the gear ratio of the target gear.

5 shows diagrams for various boost upshifts. The left column of FIG. 5 shows a 2- (1) -4 thrust upshift, in which the gear ratio of the intermediate gear is greater than the gear ratio of the initial gear. In the middle column of FIG. 5, a 2- (3) -4 thrust upshift is shown, in which the gear ratio of the intermediate gear lies between the gear ratio of the starting gear and the target gear. The right column of FIG. 5 shows a 2- (5) -4 thrust upshift, in which the gear ratio of the intermediate gear is smaller than the gear ratio of the target gear.

FIG. 6 shows diagrams for different train backward calculations. A 4- (1) -2 train downshift is shown in the left column, with the gear ratio of the intermediate gear being greater than the gear ratio of the target gear. In the middle column, a 4- (3) -2 train downshift is indicated, whereby this ratio of the intermediate gear lies between the ratio of the initial gear and the target gear. The right column shows a 4- (5) -2 train downshift, whereby the gear ratio of the intermediate gear is smaller than the gear ratio of the starting gear.

7 shows diagrams for various thrust downshifts. The left column of FIG. 7 shows a 4- (1) -2 thrust downshift, the gear ratio of the intermediate gear being greater than the gear ratio of the target gear. In the The middle column shows a 4- (3) -2 thrust downshift, the gear ratio of the intermediate gear being between the gear ratio of the starting gear and the target gear. The right column of FIG. 7 shows a 4- (5) -2 thrust downshift, the gear ratio of the intermediate gear being smaller than the gear ratio of the initial gear.

In summary, four different shift types, as already mentioned, can be defined in a dual clutch transmission, namely train upshifts, push upshifts, train downshifts and push downshifts. A circuit in which the target gear and the starting gear lie on the same input shaft can be achieved by using an intermediate gear by means of the method according to the invention without interrupting the tractive force, as can be seen from FIGS. 3 to 7.

The target gear can be assigned, for example, to the first transmission input shaft B, with a gear of the second then instead of shifting directly into the target gear

Transmission input shaft A is used as an intermediate gear. The gear ratio of the intermediate gear can be larger or smaller than the gear ratio of the initial gear and also larger or smaller than the gear ratio of the target gear.

FIG. 8 shows a double downshift via an intermediate gear according to the second exemplary embodiment of the method according to the invention on the basis of the transmission input shaft speed and the engine speed as well as the clutch torque and the engine torque.

This shift strategy proposed for downshifts provides positive moment intervention in order to reach the target speed. In this exemplary embodiment, too, multiple downshifts are carried out as a two-stage shift via an intermediate gear in the other sub-transmission.

FIG. 9 shows a schematic course of a filling torque level according to a third exemplary embodiment of the method according to the invention. With this shift strategy, a filling torque level is determined at the beginning of the shift, which is load and speed dependent via a map. The basis for the replenishment is the finish line. In contrast to the second embodiment, this method provided that the refill is increased again when the target engine speed is reached. This is particularly advantageous if the target gear is not yet engaged in the transmission after the target engine speed has been reached. Thus, at least the full moment of the old gear or the intermediate gear can be transmitted during the waiting time.

In the present method, the filling level is also maintained during the overlap with the intermediate course. As shown in FIG. 9, the filling torque level is calculated continuously, with three sections being formed. In the first section, the filling torque level z. B. degraded linearly. In a second section, the filling torque level is kept at a certain value. The filling element level is then rebuilt at the end of the speed adjustment, that is to say speed-dependent or slip-dependent, as part of a third section.

This results in the schematic course of the filling torque level according to FIG. 9, the filling torque level depending on the percentage

Driver request torque is shown. The speed of degradation, the lower filling level and the rise again at the end can be applied using a map. The rate of degradation can e.g. B. be pedal dependent. Thus, e.g. B. Downshifts can be carried out comfortably at low loads by slowly opening the clutch. Basically, the level of filling can be related to the clutch or the output torque. It has been shown that when the level of filler in relation to the clutch is constant, the engine speed increases with a constant acceleration. The increase in the level of filling torque at the end can only depend on the slip speed of the new gear and not on the speed of the intermediate gear. The map corresponds to a P controller and can hold this accordingly when the target speed is reached.

FIG. 10 shows a schematic course of a simple downshift according to the third exemplary embodiment of the method according to the invention, the course of the transmission input speed, the engine speed and the course of the

Coupling torque and the engine torque are shown over time. In contrast to this, a double downshift is shown in FIG. 11, in which the target gear is already engaged when the target speed is reached. With multiple downshifts, there are different situations depending on how quickly the target speed is engaged or reached is. In addition to the condition that the target engine speed is reached, the target gear should also be engaged before the overlap begins. In the case of multiple gearshifts in particular, the method according to the invention often reaches the target speed before the target gear is engaged. The level of refill can then be built up depending on the slip up to the driver's desired torque. Various switching situations are shown in particular from FIGS. 11 to 13, in which the target gear is engaged at different times.

If for some reason the target gear cannot be engaged and the clutch torque of the first clutch with high slip continues on the

If the desired driver torque remains, an emergency release function of the clutch can be provided to avoid overheating of the clutch, which e.g. after an applicable time, the clutch begins to open slowly. In addition, the non-shiftable gear can be recognized and replaced by a new gear specification.

A double downshift is also shown in FIG. 12, in which the target gear is not yet engaged when the target speed is reached. The coupling of the intermediate gear keeps the speed constant at maximum output torque.

FIG. 13 also shows a double downshift, the target speed being reached before overlapping on the intermediate gear.

The patent claims submitted with the application are proposals for formulation without prejudice for the achievement of further patent protection. The applicant reserves the right to claim further combinations of features previously only disclosed in the description and / or drawings.

Relationships used in subclaims indicate the further development of the subject matter of the main claim by the features of the respective subclaim; they are not to be understood as a waiver of the achievement of independent, objective protection for the combinations of features of the related subclaims. Since the subjects of the subclaims can form their own and independent inventions with regard to the prior art on the priority date, the applicant reserves the right to make them the subject of independent claims or declarations of division. They can furthermore also contain independent inventions which have a design which is independent of the objects of the preceding subclaims.

The exemplary embodiments are not to be understood as a restriction of the invention. Rather, numerous changes and modifications are possible within the scope of the present disclosure, in particular such variants, elements and combinations and / or materials, which, for example, by combining or modifying individual ones in conjunction with and described in and in the general description and embodiments and the claims Features or elements or process steps contained in the drawings can be removed by the person skilled in the art with regard to the solution of the task and, by means of combinable features, lead to a new object or to new process steps or process step sequences, also insofar as they relate to manufacturing, testing and working processes.

Claims

claims

1. A method for performing a shift in a double clutch transmission with at least two transmission input shafts, characterized in that a torque control on the clutches assigned to the transmission input shafts in

Dependence of the load condition of the double clutch transmission and / or the type of circuit is carried out.

2. The method according to claim 1, characterized in that the torque control in the shift from an initial gear to a target gear is carried out in several phases.

3. The method according to claim 2, characterized in that the torque on the drive train is controlled by controlling the two clutches and the motor in such a way that drive train vibrations are suppressed.

4. The method according to claim 3, characterized in that after a gear change signal in a first phase (phase 1), the torque-transmitting clutch of the first transmission input shaft is opened and that at the end of the first phase (phase 1) it is checked whether the drive train in Thrust or

Train operation is located.

5. The method according to claim 3 or 4, characterized in that during a second phase (phase 2) with slipping clutch of the first transmission input shaft, a slip reserve is built up by keeping the clutch torque constant and / or by appropriately increasing the engine torque as a function of the driver's desired torque, wherein the engine speed is adjusted to a target speed.

6. The method according to claim 5, characterized in that the target speed in

Train operation is determined by the maximum of the starting gear speed and the target gear speed plus the slip reserve.

7. The method according to claim 5, characterized in that the target speed in overrun is determined by the minimum of the starting gear speed and the target gear speed minus the slip reserve.

8. The method according to any one of claims 5 to 7, characterized in that if the engine torque is not sufficient to achieve the target speed, the clutch torque of the torque-transmitting clutch is additionally reduced.

9. The method according to any one of claims 3 to 8, characterized in that in a third phase (phase 3) for cross-fading the moment at the moment transmitting

Clutch with a predetermined ramp function is reduced to the value 0, while at the same time the torque on the clutch of the target gear is increased to the slip limit.

10. The method according to any one of claims 3 to 9, characterized in that in a next phase (phase 5) by increasing or reducing the engine torque depending on the driver's desired torque, the engine speed is matched with the target speed, the target speed of the engine in train operation is determined by the target speed and the slip reserve and the target speed of the engine in overrun by the target speed and

Hatch reserve is determined.

11. The method according to any one of claims 3 to 10, characterized in that in a further phase (phase 6) by correspondingly reducing or increasing the engine torque depending on the driver's desired torque and / or

Closing the clutch of the target gear a slip-stick transition is realized in order to achieve a smooth transition and to end the shift, the engine torque being reduced in traction and increased in overrun.

12. The method, in particular according to one of the preceding claims, characterized in that in a shift in which the starting gear and the target gear are assigned to a common first transmission input shaft, the starting gear is switched into an intermediate gear which is a second Gearbox input shaft is assigned, with a torque being transmitted from the second gearbox input shaft to the output shaft through the intermediate gear and the target gear being switched on the first gearbox input shaft.

13. The method according to claim 12, characterized in that after a gear change signal, the first phase (phase 1) is carried out.

14. The method according to claim 12 or 13, characterized in that the second phase (phase 2 ') is carried out, the target speed in train operation by the maximum of the starting gear speed and the intermediate gear speed plus the

Slip reserve and in overrun is determined by the minimum of the starting gear speed and the intermediate gear speed minus the slip reserve.

15. The method according to claim 14, characterized in that if the engine torque is not sufficient to reach the target speed, the clutch torque of the torque-transmitting clutch is additionally reduced.

16. The method according to any one of claims 12 to 15, characterized in that the third phase (phase 3) is carried out.

17. The method according to any one of claims 12 to 16, characterized in that in a fourth phase (phase 4) for changing gear, the starting gear is removed and the target gear is engaged.

18. The method according to any one of claims 12 to 17, characterized in that after the fourth phase (phase 4), the second phase (phase 2 ') is repeated, the target speed in train operation by the maximum of the intermediate gear speed and the target gear The speed plus the slip reserve is determined and the target speed in overrun is determined by the minimum of the intermediate gear speed and the target gear speed minus the slip reserve.

19. The method according to any one of claims 12 to 18, characterized in that the third phase (phase 3) is repeated, the cross-fading The clutch torque of the clutch of the second transmission input shaft is reduced to the value 0 with a predetermined ramp function, while at the same time the clutch torque of the clutch of the first transmission input shaft is increased to the slip limit.

20. The method according to any one of claims 12 to 19, characterized in that the fifth phase (phase 5) is carried out.

21. The method according to any one of claims 12 to 20, characterized in that the sixth phase (phase 6) is carried out.

22. The method according to any one of the preceding claims, characterized in that a positive torque intervention is carried out during the shift in order to reach the target speed.

23. The method according to any one of the preceding claims, characterized in that at the beginning of the circuit for torque control on the clutches of the transmission input shafts, a load and speed-dependent filling torque is determined and changed for speed adjustment during the shift.

24. The method according to claim 16, characterized in that the target gear is used as the basis for determining the filling torque.

25. The method according to claim 16 or 17, characterized in that the filling moment is first reduced and then for a predetermined time

Filling level is maintained and built up accordingly at the end of the speed adjustment.

26. The method according to claim 18, characterized in that the reduction of the filling torque to a predetermined filling torque level is linear and the structure is carried out depending on the speed and / or slip. 27Nerfahren according to any one of claims 16 to 19, characterized in that a

Filling torque M _mι corresponds to the sum of the applied clutch _torques ∑ _{& A} during shifting.

28. Double clutch transmission with at least two transmission input shafts, in particular for performing a method according to one of the preceding claims, characterized in that a device for torque control depending on the load condition of the double clutch transmission and / or the type of shifting is provided on the clutches assigned to the transmission input shafts.