DE102013226702A1 - A method of operating a vehicle driveline having a prime mover, a dual clutch transmission, and an output - Google Patents

Abstract

The invention relates to a method for operating a vehicle drive train (1) with a drive machine (2), with a dual-clutch transmission (3) and with an output (4). In the range of at least two partial transmissions (4, 5) of the dual-clutch transmission (3) several translations can be displayed. In the presence of a request to leave the sailing operation and / or to deactivate hybrid applications, the prime mover (2) is switched on and a current operating state of the vehicle drive train (1) is determined, as a function of which a ratio to be introduced in the area of the dual-clutch transmission (3) is determined. The rotational speed of the drive machine (2) is guided in the direction of a rotational speed value which is equivalent to a synchronous rotational speed of the gear ratio determined as a function of the operating state of the vehicle drive train (1) and to be introduced in the dual-clutch transmission (3). Transfer capabilities of hydraulically actuated clutches of a dual clutch device (11) are additionally raised and speeds of transmission input shafts (7 and 8) are thereby at least approximately out to the speed level of the rotational speed of the drive machine (2).

Description

The invention relates to a method for operating a vehicle drive train with a prime mover, with a dual-clutch transmission and with an output according to the closer defined in the preamble of claim 1. Art.

Conventionally operated vehicle drive trains, which are each designed with a prime mover, with a dual-clutch transmission and with an output, are converted into a so-called sailing mode during a reduction of fuel consumption of the drive machines during suitable operating state courses. An engine designed as an internal combustion engine is not completely switched off in known methods. The speed of the prime mover is guided during the activated sailing operation to the idle speed level, so that necessary units, such as an air conditioner, a power steering, a transmission and the like, without additional drive means are operable. Thus, for example, the connection of the prime mover to the remaining part of the vehicle drive train with a corresponding driver request in the field of the transmission within short operating times and almost instantaneously feasible. For this purpose, provided between the prime mover and the transmission clutch is held in the range of the Touchpointniveaus or near their point of contact, whereby the transmission capacity of the clutch without prior time-consuming filling of the clutch to the desired value is feasible. If, due to a changing during operation of the operating mode of the vehicle drive train before leaving the sailing operation in the transmission insert a different ratio, this is due to the idle speed level driven engine available oil supply of the transmission also delay-free feasible.

In order to reduce consumption during suitable operating state courses of vehicle drive trains, it is also provided that an engine designed as an internal combustion engine is completely switched off during a sailing operation or in various hybrid applications, wherein the prime mover is disconnected from the rest of the vehicle powertrain in the off state to minimize drag torque from the disconnected prime mover to initiate the vehicle powertrain. When leaving the sailing mode or the hybrid connections, the prime mover should again be connected as possible with little delay to the remaining part of a vehicle drive train.

Since usually a hydraulic pump of a transmission is driven by a prime mover and a hydraulic supply of a transmission is interrupted in the disconnected or decoupled operating state of a prime mover is for maintaining actuation pressures for switching elements and other components of a transmission and for Gangnachführfunktionen an oil supply to a transmission over to provide an additional electrically driven oil pump. However, such solutions increase a space requirement and the manufacturing cost of a transmission, which is why transmission systems or vehicle powertrain systems are used without additional electric oil pump.

In order to represent a requested after leaving a sailing operation or after disabling hybrid applications operating condition of a vehicle drive train within short operating times and without major delays, especially with switched on and coupled drive machine, a procedure for connecting and coupling the drive machine is used in the so-called start Stop systems of vehicle powertrains is used. During such operation, a clutch connecting the prime mover to a transmission input shaft of the transmission is already filled during the engine starting phase. This torque can be transmitted via the clutch as soon as the prime mover is running. For this purpose, however, it is necessary that in the region of the transmission a requested translation is inserted before reaching a corresponding transmission capacity of the clutch.

Are in the range of a transmission for the representation of a sailing operation with the prime mover all translations designed so when leaving the sailing operation and before coupling the prime mover via the clutch to the vehicle driveline first in the range of the transmission insert the operating state-dependent requested translation. However, this is only possible if a drive of the drive motor driven hydraulic fluid supply of the transmission is sufficient. If, in the region of a hydraulic system of the transmission, first a switching valve device for transferring the requested gear ratio into a defined switching operating state via the hydraulic supply, the requested gear ratio can only be inserted in the gearbox if the valve device of the hydraulic system reliably has this switching operating state.

In addition, it should be noted that one or more transmission input shafts having gear ratios in the range of a transmission have a speed which is at least is approximately equal to zero, and a speed in the region of the output during a sailing operation of a vehicle drive train is relatively high. As a result, during the insertion process of an operating state-dependent requested gear ratio in the region of the transmission, large differential rotational speeds are to be compensated for via a switching element designed as a synchronization. In order to generate in the vehicle powertrain no driving comfort affecting reaction moments resulting from the insertion of the requested translation, the insertion process is feasible only with relatively low switching forces in the field of synchronization. However, this disadvantageously leads to an undesirable delay until a vehicle drive train has a requested or desired operating state with a transmission engaged in the region of a transmission.

The present invention is therefore based on the object to provide a method for operating a vehicle drive train with a prime mover, with a dual-clutch transmission and with an output available, by means of which vehicle drive trains when leaving a sailing operation and / or deactivating hybrid applications within a short operating time in a desired operating condition with low loads and high ride comfort can be transferred.

According to the invention this object is achieved by a method having the features of claim 1.

In the inventive method for operating a vehicle drive train with a prime mover, with a dual-clutch transmission and with an output, wherein in the range of at least two partial transmissions of the dual clutch transmission several translations by switching on and off of hydraulically actuated switching elements can be displayed and each have a transmission input shaft of a partial transmission of the dual clutch transmission can be brought into operative connection via a hydraulically actuated clutch with continuously variable transmissibility of a dual clutch device with the prime mover, the clutches of the dual clutch system and the switching elements are transferred in the presence of a request for representing a sailing operation and / or defined hybrid applications in an open operating state and turned off the prime mover.

In the presence of a request to leave the sailing operation and / or to deactivate the hybrid applications, the prime mover is switched on and a current operating state of the vehicle drive train is determined, as a function of which a ratio to be introduced in the area of the dual-clutch transmission is determined. The rotational speed of the drive machine is guided in the direction of a rotational speed value which is equivalent to a synchronous rotational speed of the gear ratio determined as a function of the operating state of the vehicle drive train and to be introduced in the dual-clutch transmission. The transmission capabilities of the hydraulically actuated clutches of the dual clutch device are additionally increased and the rotational speeds of the transmission input shafts are thereby guided at least approximately to the speed level of the rotational speed of the drive machine.

If a driver request or a request for leaving a sailing operation and / or for deactivating one or more hybrid applications occurs while a vehicle is traveling, the rotational speed of the prime mover, which is preferably designed as an internal combustion engine, is guided according to the invention to the synchronous rotational speed that occurs in the desired driving gear. During the start of the prime mover and the startup of the prime mover to be closed clutch of the dual clutch device is already filled so that the active transmission input shaft, then the drive torque of the prime mover is guided in the direction of the output is towed up to the speed of the prime mover and the vehicle drive train within short operating times at the same time low loads, especially in the field of switching elements and high ride comfort in the desired operating condition can be transferred.

In addition, the second transmission input shaft of the dual-clutch transmission is also guided by appropriate actuation of the further clutch of the dual clutch device in the direction of the synchronous speed of the translation to be engaged, bringing both the required ratio in a partial transmission and a further translation of the dual clutch transmission in the further partial transmission at low differential speeds and therefore low Loads as well as within short operating times on the switching elements of the dual clutch transmission can be inserted.

Furthermore, the spontaneity of the actuation of the dual-clutch transmission can also be improved by means of the procedure according to the invention. In a change in the requested operating state dependent to be inserted ratio in the range of the dual clutch transmission, the dual clutch transmission is already at least partially prepared by the at least approximate synchronization of the other transmission input shaft for the connection of the newly requested translation, bringing the newly requested translation can also be inserted within short operating times with simultaneous low loads in the dual-clutch transmission.

Since both transmission input shafts are towed up to the rotational speed of the prime mover by corresponding hydraulic actuation of the two clutches of the dual clutch device via the procedure according to the invention, a gear change can be carried out without loss of time still directly before actuating a usually provided shift rod of a dual clutch transmission.

If the clutches of the dual clutch device are primed during a fast fill phase by applying a fast fill pressure level and the clutch actuation pressures are then guided from the level of the fast fill pressure to a pressure level below a fill compensation pressure level to which the transmission capabilities of the clutches are at least approximately equal to zero and from this an increase in actuation pressures causes an immediate increase in transmission capabilities, the speeds of the transmission input shafts are towed up to the desired extent to the speed of the prime mover. Both the operating state-dependent requested and to be inserted in the field of a partial transmission ratio as well as a to be represented in the other sub-transmission further translation are essentially inserted with low loads in the range of switching elements to be actuated because of the clutches during the application of pressure less than the Füllausgleichdruckniveau no significant torque from the prime mover can be introduced into the dual-clutch transmission.

The requested operational state dependent to be engaged translation is then loaded with the least possible loads in the field of switching elements of the dual clutch transmission when the operating pressure of the clutch, which is associated with the partial transmission in which the requested translation by pressing at least one of the switching elements is inserted, as long as at least approximately on the Level is maintained below the Füllausgleichdruckes until the requested ratio is switched in the partial transmission.

The vehicle drive train can be converted into the desired operating state within short operating times with simultaneously high driving comfort, when the actuating pressure of the clutch associated with the partial transmission in which the requested gear ratio is to be engaged by actuating at least one of the shift elements, in the partial transmission engaged requested ratio starting from the pressure level is guided below the Füllausgleichsdruckes preferably via a pressure ramp to a closing pressure level at which the clutch has the full transfer capability.

Is the operating pressure of the clutch, which is assigned to the partial transmission, in which the requested translation is inserted by pressing at least one of the switching elements, after the Schnellfüllphase from the pressure level below the Füllausgleichsdruckes preferably via a pressure ramp to an opening pressure level out to which the transmission capacity of the clutch at least is approximately zero, is avoided in a simple manner that a speed of the transmission input shaft is guided by the prime mover to values above the synchronous speed of the determined depending on the operating condition of the vehicle drive train and to be introduced in the dual clutch transmission and the translation to be inserted with low loads and high ride comfort can be inserted within short operating times. In the case of a further advantageous variant of the method according to the invention which causes low loads in the area of the switching elements, the required ratio is switched on at at least approximately completely open coupling.

If the actuation pressure of the clutch associated with the sub-transmission in which the requested gear ratio is to be engaged by actuating at least one of the shift elements is engaged in the transmission requested in the sub-transmission via a further Schnellfüllphase, an adjoining Füllausgleichsphase and in turn subsequent pressure ramp on led a closing pressure level at which the clutch has its full transfer capability, a possible stress-free operation of the dual clutch transmission is feasible and a vehicle powertrain with high ride comfort within a short operating times in a requested operating condition can be transferred.

In a further advantageous variant of the method according to the invention, the actuating pressure of the clutch, which is assigned to the partial transmission, in which a translation is at least approximately adjacent to the required ratio, after the Schnellfüllphase from the pressure level below the Füllausgleichdruckes preferably lowered via a pressure ramp to a pressure value, to which a transmission capacity of the clutch is at least approximately equal to zero. This ensures that the transmission input shaft associated with the clutch is guided by the drive machine at least partially in the direction of the synchronous speed of the ratio determined as a function of the operating state of the vehicle drive train and to be engaged in the dual-clutch transmission and then in their open operating state passes, to which the adjacent translation in the partial transmission at low loads can be inserted. On the switching element to be actuated for the connection of the adjacent translation then lower differential speeds in the range of the sub-transmission are then compensate. In addition, due to the substantially open coupling, no additional torque acting counter to the switching operation of the adjacent translation in the region of the switching element, whereby the loads in the region of the switching element can be kept low in a simple manner.

In a further advantageous variant of the method according to the invention, the gear ratio to be engaged is requested to be engaged at least approximately adjacent transmission in the partial transmission with engaged requested translation by actuating a switching element, whereby the insertion process of at least approximately adjacent translation in the partial transmission does not affect the connection of the requested operating state dependent to be inserted translation ,

Both the features specified in the claims and the features specified in the subsequent embodiments of the subject invention are each suitable alone or in any combination with each other to further develop the subject invention. The respective feature combinations represent no limitation with respect to the development of the subject matter according to the invention, but essentially have only an exemplary character.

Further advantages and advantageous embodiments of the subject invention emerge from the claims and the embodiments described in principle below with reference to the drawings, wherein in the description of the various embodiments in favor of clarity for construction and functionally identical components, the same reference numerals are used.

It shows:

1 a highly schematic representation of a vehicle drive train with a prime mover, with a dual-clutch transmission and with an output;

2 several courses of different operating variables of the vehicle drive train according to 1 that settle when leaving a sail operation during a conventional operation of the vehicle drive train;

3 several courses of different operating variables of the vehicle drive train according to 1 that settle when leaving a sailing operation during a mode of operation according to the invention according to a first variant of the method according to the invention; and

4 several courses of different operating variables of the vehicle drive train according to 1 that settle when leaving a sailing operation when operating according to the invention according to a second variant of the method according to the invention.

1 shows a vehicle drive train 1 with an engine running as an internal combustion engine 2 , with a dual-clutch transmission 3 and with a downforce 4 , In the range of two partial transmissions 5 . 6 of the dual-clutch transmission 3 are several translations by switching on and off of hydraulically actuated and preferably designed as synchronizers and not shown in the drawing switching elements representable. In each case a transmission input shaft 7 or 8th a sub-transmission 5 or 6 is via a preferably designed as a frictional switching element coupling 9 or 10 a double clutch device 11 with the prime mover 2 can be brought into operative connection. The transmission output side are the partial transmission 5 and 6 with a transmission output shaft 12 in operative connection, in turn, with the output 4 connected is.

The couplings 9 and 10 of the double clutch system 12 and the switching elements of the dual clutch transmission 3 be transferred to an open operating state in the presence of a request for representing a sailing operation of the vehicle drive train. At the same time the prime mover 2 shut down to minimize fuel consumption of the prime mover to a minimum. This causes one to interfere with the vehicle driveline 1 executed vehicle during a sailing operation with the prime mover off 2 and designed translations in the field of dual-clutch transmissions 3 at the same time uncoupled from the transmission engine 2 is operated.

If there is a corresponding requirement for leaving the sailing operation, the prime mover becomes 2 switched back on. This leads to a hydraulic supply of the dual-clutch transmission 3 and thus the hydraulically actuated shift elements and the hydraulically actuated clutches 9 and 10 with increasing speed of the prime mover 2 on to operate the clutches 9 and 10 and the switching elements of the dual-clutch transmission required level is performed.

In addition, when there is a request to exit the sail operation, a current operating state of the vehicle driveline is 1 determined and depending on a in the range of the dual clutch transmission 3 to be inserted translation determined. This translation is either in the range of the sub-transmission 5 or in the area of the sub-transmission 6 insert, in turn, in the area of a hydraulic control unit to perform an actuation pressure in the direction of a piston-cylinder device and to actuate an adjustable switching element accordingly.

Will the vehicle powertrain 1 controlled in a conventional manner in the presence of a request to leave the sailing operation, which are in 2 shown courses of different operating variables of the vehicle drive train 1 in the manner described in more detail below. In this case, there is a request for leaving the sailing operation of the vehicle drive train at a time T1 1 before, which is why the prime mover 2 is started and a speed n2 of the prime mover 2 increases in the extent shown. The two clutches 9 and 10 are fully opened and a target operating pressure p9soll and p10soll, respectively, and an actual operating pressure p9ist and p10ist, respectively, of the clutch 9 or 10 has an opening pressure level p9o and p10o, respectively, to which a transmission capability of the clutch 9 or 10 is equal to zero.

Because in the area of the dual-clutch transmission 3 all provided for switching on and off the translations hydraulically actuated switching elements in the open operating state, is in the dual clutch transmission 3 none of the translations filed. Depending on the currently determined operating state of the vehicle drive train 1 becomes one in the area of the dual-clutch transmission 3 to be inserted translation determined and it is one of the synchronizing designed as switching elements by applying an actuating pressure to convert into its closed operating state. For this purpose, an actuation pressure in the region of a piston-cylinder device is applied and displaced connected to a piston of the piston-cylinder device switching rod in a conventional manner, whereby the gear ratio to be engaged associated switching element is again actuated to the desired extent. A position of this shift rod, which has its first axial end position at time T1, is over the operating time t through the course S in 2 graphically rendered.

At a further time T2 is in the range of the dual-clutch transmission 3 ascertains that the piston-cylinder device associated with the ratio to be engaged is acted upon by the hydraulic control unit to the desired extent with actuation pressure, for which reason the actuating rod to be actuated is moved out of its first axial position in the direction of its second axial end position in which the requested gear ratio is engaged is.

Since the last described operating condition of the vehicle drive train 1 neither the clutch 9 still the clutch 10 a corresponding transmission capability for transmitting torque from the prime mover 2 in the direction of the transmission input shaft 7 or 8th and in the region of the dual-clutch transmission 3 no translation is inserted, is in the range of to engage the requested translation to be operated switching element, a high differential speed. The differential speed results from a speed n7 or n8 of the transmission input shaft 7 or 8th at time T2 is very low while the speed is in the range of the output 4 and thus also the transmission output shaft 12 is much higher. To that of the requested translation associated switching element in the range of the sub-transmission 5 or 6 to be able to close, is via the switching element, the differential speed between the input shaft 7 or 8th and the transmission output shaft 12 to balance or to lead in a favorable for the production of the positive adhesion in the region of the switching element differential speed window. This required for the connection of the requested translation operating condition of the vehicle drive train 1 in the area of the dual-clutch transmission 3 or the switching element to be closed is present only at a time T3, to which the speed n7 or n8 of the transmission input shaft 7 or 8th has a corresponding speed value.

For the sake of clarity, the following description is given 2 the assumption that the requested translation in the partial transmission 5 is inserted and in the partial transmission 6 the so-called shadow corridor.

From the time T3, the shift rod is the course S adjusted with high gradient in the direction of the second axial end position and reaches this at the time T4, to which the requested translation in the dual-clutch transmission 3 in the area of the sub-transmission 5 is inserted. At the same time, the setpoint actuating pressure p9setpoint is set to a rapid filling pressure p9s and a filling compensation pressure p9f from time T4 in the illustrated manner during a fast filling phase extending up to a time T5 and a filling compensation phase ending at a time T6 and the clutch 9 for a connection in an operating state transferred to the clutch 9 at time T6 and to which the actual Actuation pressure p9 is approximately equal to the target pressure specification p9soll. At time T6, the transmission capability of the clutch 9 at least approximately zero and further raising of the actual operating pressure p9ist has an immediate increase in the transmissibility of the clutch 9 result.

Furthermore, at the time T6 in the partial transmission 6 a switching element actuated to the partial transmission 6 an at least approximately to the inserted translation adjacent translation in the dual clutch transmission 3 insert, which is also referred to as a so-called shadow corridor. For this purpose, a differential speed between the transmission input shaft in the region of the switching element 8th and the transmission output shaft 12 balance, taking in the field of transmission input shaft 8th To be set speed of the synchronous speed corresponding to the inserted and at least approximately adjacent translation to previously engaged translation in the transmission input shaft 8th established.

Since in the range of zuzuschaltenden switching element of the sub-transmission 6 present differential speed is very high, the switching element is only after a longer period of operation at a time T7 by adjusting an associated shift rod whose axial position is represented by the course S1, adjustable in the extent shown and displaceable in its second axial position, they to reached a time T8, whereby the at least approximately adjacent translation at time T8 in the dual-clutch transmission 3 is inserted.

To the vehicle drive train 1 in the presence of a request to leave the sailing operation much earlier than at the time T6 in the so-called coupled operating state, the vehicle drive train according to the following and based on the representation of 3 operated approach described in more detail, by means of the additionally to be actuated each switching elements of the dual clutch transmission 3 be charged to a much lesser extent during Ankoppelvorganges.

At time T1, in turn, there is the request to exit the sail operation, where the vehicle driveline 1 at time T1, the above-described operating condition with open clutches 9 and 10 and in the region of the dual-clutch transmission 3 none of the translations is inserted. In addition, also the prime mover 2 switched off, which is why the speed n2 of the prime mover 2 at time T1 is equal to zero.

With the presence of the request to leave the sailing operation is the prime mover 2 started and at the same time a target pressure specification of the operating pressure p9soll the clutch 9 and p10soll of the clutch 10 raised from the opening pressure level p9o or p10o in the direction of the Schnellfülldruckniveaus p9s and p10s. The to engage the operating state dependent requested translation to shift rod and provided for inserting the shadow gear further shift rod of the dual clutch transmission 3 are at time T1 each in their first axial end position.

Due to the connection of the prime mover 2 increases the speed n2 of the prime mover 2 with increasing operating time t to the extent shown. At a time T7, the actual pressure p9ist or p10ist of the clutch increases 9 or the clutch 10 due to a system-related delayed response as a function of the target pressure specification p9soll or p10soll slowly, which is why an operative connection between the prime mover 2 and the two transmission input shafts 7 and 8th to a certain extent. This causes the speeds n7 and n8 of the transmission input shafts 7 and 8th from the prime mover 2 over the couplings 9 and 10 be towed, the speed n2 of the prime mover 2 even in the direction of the synchronous speed n2sync of the transmission input shaft 7 or 8th is guided, which is in the dual-clutch transmission 3 inserted operating state dependent requested translation sets.

At a time T8, before the speed n2 of the prime mover 2 and the rotational speeds n7 and n8 of the transmission input shafts 7 and 8th reach the synchronous speed n2sync, the target pressure specifications p9soll and p10soll of the clutches become 9 and 10 lowered from the Schnellfülldruckniveau p9s or p10s to a pressure level below the Füllausgleichsdruckniveaus p9f or p10f in the illustrated extent, so that the transmission capabilities of the couplings 9 and 10 in turn be reduced and the requested translation in the range of the sub-transmission 5 or 6 as well as the shadow gear in the area of the sub-transmission 6 or 5 without the couplings 9 and 10 applied torque in the dual-clutch transmission 3 can be inserted.

The following description is based on the assumption that in the dual-clutch transmission 3 after leaving the sailing mode operating condition-dependent to be inserted translation in the range of the sub-transmission 5 is to represent and the clutch 9 is completely close to one with the vehicle powertrain 1 executed vehicle in the desired extent with coupled and switched drive machine 2 to be able to operate.

For this reason, from the time T8 to a point in time T9, the target pressure specification p9setpoint is left at a pressure level just below the filling compensation pressure p9f at which the requested gear ratio in the partial transmission 5 is fully inserted. The desired pressure curve p10soll of the clutch 10 is led from the time T8 via a pressure ramp in the direction of the opening pressure level p10o, to which the clutch 10 is completely open. With increasing operating time t, the actual pressure curves p9ist and p10 are equal to the target pressure specifications p9soll and p10soll, for which reason the rotational speed n7 from time T8 is substantially equal to the rotational speed n2 of the prime mover 2 is, while the speed n8 of the transmission input shaft 8th decreases with increasing operating time t compared to the rotational speeds n2 and n7.

Since both the speed n2 of the prime mover 2 as well as the speed n7 of the transmission input shaft 7 At a time T10 at least approximately correspond to the synchronous speed n2sync, which is to insert the requested translation to be actuated shift rod of the sub-transmission 5 actuated to the required extent with actuating pressure in the region of the piston-cylinder device and actuates the associated switching element or the associated synchronization, wherein this is almost in the synchronous operating state. This offers the possibility to move the operating rod to be actuated within a short operating time up to the time T10 in its second axial end position and the requested translation completely in the partial transmission 5 appeal. This is the case at the time T9, at the same time the target pressure specification p9soll the clutch 9 in the illustrated scope is first jump-shaped to the pressure level of the Füllausgleichdruckes p9f is raised and then passed over a pressure ramp in the direction of the closing pressure level to the clutch 9 to close completely in the desired extent.

In addition, from the time T9 also for inserting the so-called shadow gear in the partial transmission 6 adjusted to actuated shift rod and increasingly engaged to insert the shadow gear to closing switching element, which from the time T9, the rotational speed n8 of the transmission input shaft 8th in the direction of the synchronous speed n8sync is performed, which is in the partial transmission 6 inlaid translation of the shadow aisle sets.

Due to the above additional actuation of the clutches 9 and 10 is the operating condition of the vehicle driveline to be established by the sail leave request 1 compared to the basis 2 described in more detail and already known from practice at the time T9 and thus significantly before the time T6 reached. In the area of the switching elements or the synchronizations of the dual-clutch transmission 3 be in inventive operation of the vehicle drive train 1 causes significantly lower loads during the production of the requested operating condition, as in the field of switching elements significantly lower differential speeds during the insertion operations of the translations in the field of partial transmissions 5 and 6 are to be compensated.

Will the vehicle powertrain 1 according to 1 operated analogously to a further variant of the method according to the invention, the in 4 shown in more detail courses of various operating variables. According to the progressions 4 The underlying procedure differs from the one according to the processes 3 underlying approach essentially by the operation of the clutch 9 Therefore, in the following description, essentially only the differences of the two approaches will be discussed in more detail and with regard to the rest of the procedure to the above description 3 is referenced.

In contrast to the courses according to 3 The underlying procedure is setpoint pressure specification p9setpoint of the clutch 9 at the time T8 to the same extent as the target pressure specification p10soll the clutch 10 lowered in the direction of the pressure level of the opening pressure p9o and the clutch 9 fully opened to the partial transmission 5 and completely relieve their switching elements on the input side. This is for example advantageous if the speed n2 of the prime mover 2 not like in 3 and 4 shown idealized without speed overshoot in the direction of the synchronous speed n2sync is performed and the speed n7 is set to the desired extent without deviations also in a harmonic manner to the level of the synchronous speed n2sync.

By fully opening the clutch 9 from the time T8, the speed n7 of the transmission input shaft increases 7 essentially from a time T11 regardless of the rotational speed n2 of the prime mover 2 in the direction of the synchronous speed n2sync, since the clutch 9 is fully open at this time and the operative connection between the transmission input shaft 7 and the prime mover 2 is essentially completely interrupted. At the time T11 is again that of the partial transmission 5 actuated shift associated shift rod actuated and the associated switching element in the partial transmission 5 trying to close. Since friction surfaces come into contact with one another in the region of the switching element to be closed, the rotational speed n7 of the transmission input shaft increases 7 with increasing operating time t after the time T11 with progressively smaller gradient in the direction of the synchronous speed n2sync and is maintained at this speed value, wherein at the time T12 turn the requested ratio in the dual-clutch transmission 3 is fully inserted and the transmission input shaft 7 in the area of the sub-transmission 5 preferably positive fit with the transmission output shaft 12 connected is.

For this reason, the target pressure specification p9soll of the clutch 9 at the time T12 in the illustrated manner to the pressure level of the Schnellfülldruckes p9s raised and at a time T13 to the pressure level of the Füllausgleichdruckes p9f lowered to the clutch 9 to prepare for the connection in the manner described above. From a point in time T14, the setpoint pressure specification p9 setpoint is raised from the pressure level of the filling compensation pressure p9f in the direction of the closing pressure level via a pressure ramp to the clutch 9 completely close.

Also in the last-described procedure, the vehicle drive train 1 compared to the too 2 described in detail and known per se procedure for operating the vehicle drive train 1 at the time T9 and thus significantly before the time T6 transferred to the requested operating state, wherein the requested operating state also again with significantly lower loads in the field of switching elements of the partial transmission 5 and 6 is adjustable.

About the procedure according to the invention excessive loads on the switching elements and the synchronizations of the partial transmission of a dual clutch transmission are generally avoided. In addition, a so-called Befüllimpuls in the range of the other sub-transmission associated clutch is impressed already during the actuation of the switching element in the sub-transmission in which the requested translation is inserted, to also lead the so-called passive transmission input shaft in the direction of the rotational speed of the engine and the Differential speed in the range of the switching element or the synchronization of the other sub-transmission also significantly reduce to the desired extent.

This has in addition to the relief of the switching element or the synchronization the advantage that the Gangeinlegen the shadow corridor or the Passivganges is not noticeable. Furthermore, a serious time advantage is achieved in a so-called change of mind with respect to the ratio to be introduced in the dual-clutch transmission. Namely, both transmission input shafts are guided by a corresponding actuation of the clutches of the dual clutch device in the direction of the rotational speed of the drive machine, a change of the gear ratio to be engaged in the dual clutch transmission without loss of time even before an operation of a shift rod or the like.

In general, the speed of the prime mover is guided in the presence of a request for leaving a sailing operation and / or for deactivating a hybrid application to the synchronizing speed which is established when the operating state-dependent requested transmission is engaged. During the start and run-up of the prime mover already the clutches of the dual clutch device are filled so far, so that the transmission input shaft of the dual clutch transmission 3 , which is associated with the translation to be inserted, is towed up to the speed of the prime mover. As soon as the transmission input shaft has reached the synchronous rotational speed or is in the desired range of the synchronous rotational speed, the actuating pressure of the clutch is reduced again, so that the gear to be synchronized in the region of the dual clutch transmission can now be engaged with the clutch disengaged. The pressure level of the open clutch may be slightly below the touchpoint or a so-called Füllgleichgleichsdruckes or there is a complete opening of the clutch is performed.

Since, due to the target rotational speed of the engine and the synchronous operation of the clutch, a synchronous operation in the range of gear wheels of the clutch gear is now set, the requested ratio can now be inserted immediately with relatively little synchronous force within a short operating times.

With the above-described procedures, although the gear actuator can not be active, synchronous operation is already generated in each case with the clutches of the dual clutch device in the region of the gear wheels. Due to the fact that the coupling is then filled by the clutch filling during the Gangeinlegevorgang, this can then, if the requested ratio is engaged, are performed with a comparatively short filling time to the requested clutch desired torque.

Characterized in that the clutch is pre-filled during the engine ramp-up phase and by the pre-filling of the clutch synchronous running in the region of the gear wheels of the dual-clutch transmission is generated, the synchronization time is significantly reduced during engagement. In addition, the clutch is not to be filled out of a completely deflated state during the closing process, whereby the clutch itself can be actuated within a short operating times to the desired extent.

LIST OF REFERENCE NUMBERS

1

 Vehicle powertrain

2

 prime mover

3

 Double clutch

4

 output

5, 6

subtransmissions

7, 8

Transmission input shaft

9, 10

clutch

11

Dual clutch assembly

12

Transmission output shaft

n

 rotation speed

n2sync

Synchronous speed

n8sync

Synchronous speed

p9f, p10f

Füllausgleichsdruck

p9 is p10ist

actual pressure

p9o, p10o

opening pressure

p9s, p10s

closing pressure

p9soll, p10soll

Demand pressure setting

S, S1

course

T1 to T12

discrete time

t

 uptime

Claims (9)

Method for operating a vehicle drive train ( 1 ) with a prime mover ( 2 ), with a dual-clutch transmission ( 3 ) and with an output ( 4 ), wherein in the range of at least two partial transmissions ( 5 . 6 ) of the dual-clutch transmission ( 3 ) several translations by switching on and off of hydraulically actuated switching elements can be displayed and in each case a transmission input shaft ( 7 . 8th ) of a sub-transmission ( 5 . 6 ) of the dual-clutch transmission ( 3 ) via a hydraulically actuated clutch ( 9 . 10 ) with infinitely variable transmission capability of a dual clutch device ( 11 ) with the prime mover ( 2 ) can be brought into operative connection, and wherein the couplings ( 9 . 10 ) of the dual clutch system ( 11 ) and the switching elements in the presence of a request for representing a sailing operation and / or defined hybrid applications in an open operating state are transferred and the prime mover ( 2 ) is switched off, characterized in that in the presence of a request to leave the sailing operation and / or to deactivate the hybrid applications, the prime mover ( 2 ) and a current operating state of the vehicle drive train ( 1 ), as a function of which one in the area of the dual-clutch transmission ( 3 ) is determined, wherein the rotational speed (n2) of the prime mover ( 2 ) is guided in the direction of a rotational speed value which corresponds to a synchronous rotational speed (n2sync) which depends on the operating state of the vehicle drive train ( 1 ) and in the dual-clutch transmission ( 3 ) is equivalent translation, and wherein the transmission capabilities of the hydraulically actuated clutches ( 9 . 10 ) of the dual clutch device ( 3 ) and the rotational speeds (n7, n8) of the transmission input shafts ( 7 . 8th ) thereby at least approximately to the speed level of the rotational speed (n2) of the prime mover ( 2 ). Method according to claim 1, characterized in that the couplings ( 9 . 10 ) of the dual clutch device ( 11 ) are prefilled during a fast fill phase by applying a fast fill pressure level (p9s, p10s) and the actuation pressures (p9, p10) of the clutches (p9s, p10s) 9 . 10 ) are then guided from the level of the fast filling pressure (p9s, p10s) to a pressure level below a Füllausgleichsdruckniveaus (p9f, p10f), to which the transmission capabilities of the couplings ( 9 . 10 ) are at least approximately equal to zero and from which an increase in the actuation pressures (p9, p10) causes an immediate increase in the transmission capabilities. Method according to Claim 2, characterized in that the actuating pressure (p9) of the clutch ( 9 ), which the partial transmission ( 5 ) is assigned, in which the requested translation by inserting at least one of the switching elements is to be inserted, as long as at least approximately at the level below the Füllausgleichsdruckes (p9f) is held until in the partial transmission ( 5 ) the requested translation is inserted. Method according to claim 2 or 3, characterized in that the actuating pressure (p9) of the clutch ( 9 ), which the partial transmission ( 5 ) is assigned, in which the requested translation by inserting at least one of the switching elements is to insert, in the partial transmission ( 5 ) inserted requested translation starting from the pressure level below the Füllausgleichsdruckes (p9f) is preferably guided via a pressure ramp to a closing pressure level to which the clutch ( 9 ) has full transmission capability. Method according to Claim 2, characterized in that the actuating pressure (p9) of the clutch ( 9 ), which the partial transmission ( 5 ), in which the requested gear ratio is to be engaged by actuating at least one of the switching elements, after the rapid filling phase from the pressure level below the Füllausgleichsdruckes (p9f) preferably via a pressure ramp to an opening pressure level (p9o) is performed to which the transmission capacity of the clutch ( 9 ) is at least approximately zero. A method according to claim 5, characterized in that the requested translation at at least approximately fully opened coupling ( 9 ) is switched on. Method according to claim 5 or 6, characterized in that the actuating pressure (p9) of the clutch ( 9 ), which the partial transmission ( 5 ) is assigned, in which the requested translation by inserting at least one of the switching elements is to insert, in the partial transmission ( 5 ) inlaid requested translation over another Schnellfüllphase, a subsequent Füllausgleichsphase and in turn subsequent pressure ramp is led to a closing pressure level to which the clutch ( 9 ) Has its full transfer capability. Method according to one of claims 2 to 7, characterized in that the actuating pressure (P10) of the clutch ( 10 ), which the partial transmission ( 6 ), in which a translation at least approximately adjacent to the required ratio can be represented, after the rapid filling phase from the pressure level below the filling compensation pressure (p10f) is preferably lowered to a pressure value (p10o) via a pressure ramp, to which a transmission capacity of the clutch ( 10 ) is at least approximately equal to zero. A method according to claim 8, characterized in that the translation to be inserted at least approximately adjacent translation in the partial transmission ( 6 ) is switched on when the requested translation by pressing a switching element.

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