DE10150597A1 - Automobile drive train operating method, involves controlling operation of double clutch during gear shifting with prevention of gear shifting until clutch operation is completed - Google Patents

Abstract

The operating method uses an electronic control (16) for controlling the double clutch (10) between the automobile engine and a transmission with 2 drive input shafts during gear shifting, with gear shifting momentarily prevented until completion of the clutch operation, the drive torque transmitted by the clutch equal to that delivered by the engine, or only slightly less than that delivered by the engine. An Independent claim for an automobile drive train is also included.

Description

The invention relates, inter alia, to a method for operating a a powertrain belonging to a motor vehicle, comprising: a Drive unit, possibly in the form of an internal combustion engine; a gearbox with at least two transmission input shafts and at least one Transmission output shaft, with a first transmission input shaft at least a first gear of the transmission and a second transmission input shaft is assigned to at least a second gear of the transmission; and a Multiple arranged between the drive unit and the gear Coupling device, possibly double coupling device, for Torque transmission between the drive unit and the transmission, which is one of the first clutch arrangement assigned to the first transmission input shaft and a second assigned to the second transmission input shaft Has clutch arrangement, the two clutch arrangements independently are operable from each other.

Such a method is for example from DE 196 31 983 C1 known and relates to switching between two gears and Related to the redistribution of the drive torque Drive unit between a first and a second transmission input shaft by operating the clutch arrangements in opposite directions. Another such process was in the on 01/01/2001 German patent application Akz. 101 01 176.8 suggested that also switching between two gears with corresponding counter-actuation of the coupling devices, namely in particular advantageous switching sequences in this context.

In contrast, the present invention relates to the operation of the Drive train or of the motor vehicle having the drive train Occurring, possibly approximately stationary operating states in which i) one gear from the first and second gear is engaged, ii) one Drive torque from the drive unit via that assigned to the gear engaged Coupling arrangement of the first and the second coupling arrangement to the relevant transmission input shaft and from it via the transmission is transmitted to the driven wheels of the motor vehicle, iii) a any shifting of the transmission between two or more gears including a coordinated actuation of the Coupling device is completed and iv) currently no shifting of the transmission between two or more courses including one on top coordinated actuation of the coupling device.

For such an operating status, we will start with proposed method proposed according to a first aspect of the invention, that the clutch arrangement transmitting the drive torque in such a way is operated, or is held in such an operating state, that the moment she can transmit is exactly one of the Drive unit corresponds to the torque output or is slightly less than this.

According to this invention proposal, depending on the type the coupling device achieved various advantages. On The design-independent advantage is that the drive torque is transmitted Coupling arrangement with very short response times disengaged as required can be, quasi from the start of the corresponding operation of the clutch arrangement to that transmitted via the clutch arrangement Moment decreases. Would the clutch assembly be more engaged than Transmission of the engine torque itself is necessary, so that's in this clutch state transmissible torque above that of the Drive unit delivered or retrievable moment, so changes from the clutch arrangement transmitted torque when actuated in Release direction until the clutch assembly transferable torque to the drive unit retrievable moment is reduced. Corresponding dead times when actuated the clutch assembly are so according to the invention avoided what especially in emergency situations or in the event of a urgent shift request or ABS intervention, Anti-slip control intervention (ASR intervention) or driving stability intervention (ESP intervention) of large Advantage is.

In the case of hydraulically operated clutch assemblies, in particular of the NOR to be preferred in the case of a load switching system PAINTED OPEN type, with integrated in the coupling device, assigned to the clutch arrangements for their actuation hydraulic slave cylinders, which have a rotating union on a associated hydraulic pressure source are connected, also results in great advantage that the hydraulic pressure in the area of the rotating union is kept comparatively small. With such couplings of the NOR PAINTINGLY OPEN type is used for torque transmission by the Clutch (clutch arrangement) always requires an operating pressure that set, for example, via an electromagnetic proportional valve wild. The higher the torque that can be transmitted by the clutch arrangement, the stronger the friction surfaces (possibly plates) of the Coupling arrangement are pressed together, which is a correspondingly higher Actuation pressure required. The problem with this is that this hydraulic pressure can be introduced into the rotating clutch assembly must have some kind of rotary union. The rotary union represents a very considerable cost factor. For cost reasons is the technical effort regarding the rotary union in Want to keep boundaries and do not provide a 100% seal.

The higher the actuation pressure for actuating the Coupling device, the greater the leakage at the rotating union. It has even showed that the leakage at the rotating union is greater increasing pressure increases comparatively strongly (disproportionately). This leads to about a leakage compensation as a pressure source serving pressure oil pump should have very long duty cycles. Due to the correspondingly large service life requirements higher quality and therefore more expensive components (this is one for large ones Electric drive motors designed for life are significantly more expensive than one Motor for shorter duty cycles). Moreover, takes the system efficiency with increasing leakage at the Rotating union from. So in the case of an electric pressure oil pump through the longer operating time more electrical energy are required.

Is the actuation pressure for the Coupling arrangement set just about so large that the transmitted Torque corresponds to the engine torque, the leakage is achieved in the rotating union is only just as large as this is absolutely necessary for the Transmission of the moment is required.

That of the intrusive solution, namely after one Shaft process the clutch assembly transferred the moment completely close (i.e. - in the case of a hydraulically operated Coupling arrangement of the NORMALLY OPEN type - the maximum hydraulic Setting pressure), moving solution according to the invention thus achieved according to the above for all coupling types or designs of the Powertrain essential benefits.

Although the invention was related to development work regarding multiple clutch devices, specifically Double coupling devices made. In fact, the proposed invention is also for simple (conventional) couplings with only one Coupling arrangement and accordingly a conventional (simple) transmission applicable with only one transmission input shaft, and the above discussed advantages also for such a conventional Coupling device or a conventional drive train reached. Accordingly, the invention proposes according to the first aspect (compared to the preceding explanations in general) before a method for Operation of a drive train belonging to a motor vehicle, the comprises: a drive unit, possibly in the form of an internal combustion engine; on Transmission with at least one transmission input shaft and at least one Transmission output shaft; and one between the drive unit and the Gearbox arranged clutch device for torque transmission between the drive unit and the transmission. It becomes special about this proposed that in an operating state in which i) a gear of Gearbox is inserted, ii) a drive torque from the drive unit via a the clutch arrangement of the gear engaged Coupling device to an associated transmission input shaft and from this the transmission is transmitted to the driven wheels of the motor vehicle iii) any shifting of the transmission between two or more Gears including a coordinated actuation of the Coupling device is complete and iv) currently no switching of the Transmission between two or more gears including one thereon coordinated actuation of the coupling device is pending Coupling arrangement transmitting drive torque is actuated or is held in such an operating state that that of her transmissible moment exactly one output by the drive unit Moment equals or is slightly less than this.

One may fear that the clutch assembly is difficult to be operated exactly so that that which can be transmitted from the clutch arrangement Torque exactly the same as that delivered or delivered by the drive unit retrievable moment is how this per se to avoid clutch slippage and thus wear on the one hand and to achieve the addressed On the other hand, advantages may seem highly desirable. It has shown, however, that one can tolerate slight slip can, without increasing the life of the Coupling device is significantly reduced. Rather, it becomes particularly preferably suggested that the of the Torque-transmitting clutch arrangement (assigned to the selected gear) transmitted torque slightly less than that from the drive unit is given moment and that a resulting minor Slip (hereinafter also called micro-slip) on this Coupling arrangement by corresponding actuation of the coupling arrangement in a target range is maintained. The fact is that in the event that the speed of the drive unit is the same as that Transmission input speed is (slip zero), it is very difficult to make a statement at all in terms of whether the clutch torque is much larger, a little greater than or equal to or as the engine torque. You leave on the other hand a certain slip (e.g. the differential speed Δn ≍ 10-20 U / min), so you can use the differential speed as a measure of the approximation of the clutch torque to the torque of the drive unit (engine torque) take and the clutch torque occurring accordingly Track changes in the torque of the drive unit.

Regarding the term "micro slip" used here is on it to point out that this is not intended to address any slip that occurs in a fully engaged clutch assembly with maximum contact pressure could occur and is technically of minor relevance (a Differential speed Δn per minute is for such, by the term "Micro slip" slip not mentioned here can hardly be specified), but a slip with a differential speed Δn in the order of about 1 rpm or greater, for example with a differential speed Δn of at least 1 rpm, typically 10 to 20 rpm. or even greater.

Another advantage of the proposed micro-slip in Is in connection with a clutch device of the wet-running lamella type, that the slippage prevents the slats from prolonged Stick to one another in the same gear. Would the slats stick together, you would have to initiate a switchover Disengage the clutch assembly so that the disks are apart tear. This tear-off process takes place in such a short time Time interval from that it is not possible to get the clutch assembly fast enough to operate again in the direction of engagement in order to move the Clutch assembly to keep transmitted torque constant. It would become one temporary slipping of the clutch assembly come, causing the speed of the drive unit would shoot up undesirably. Continuous overlap between the two Coupling arrangements of a double or multiple coupling device in one Power shifting of the transmission would be made considerably more difficult or even difficult become impossible. Furthermore, the slats would be affected by such Tearing processes are heavily loaded and could be damaged in the long run.

On the other hand, this allows after the training proposal provided slight slip that that for an overlap circuit required, continuous slip increase gently and without jerks or Soaring of the drive unit can be initiated. Hysteresis at actuation due to friction in the actuation system (e.g. in hydraulic slave cylinders) are avoided or at least reduced. By the avoidance of tearing off also shows the covering life elevated.

There is particular emphasis on regulated operation of the torque-transmitting (assigned to the gear engaged) clutch assembly Basis of a differential speed characterizing the micro slip and a predetermined or dependent on at least one Determine operating parameters and / or at least one driving parameter Target differential speed thought. For example, an automatic Controllers can be used in a computing unit, which advantageously as a PI Regulator can be executed. This controller receives one as the setpoint predetermined or - preferably - one depending on the named Parameters determined differential speed value. Different parameters of the controller, for example the control characteristic of the same can also determine from such parameters as pressure, Speed, temperature, etc., depending on and during operation be adjusted accordingly. For special operating situations, for example this controller can be switched off during a switching operation or receives another one, for example predetermined by a computing unit Setpoint that corresponds to the current situation (especially driving situation) is adjusted. Such operating situations are such. B. an idle state ABS / ASR intervention etc.

Such a controller can be used to safely achieve that the clutch slip does not become too large (for example not over a differential speed of 100 rpm increases), and that on the other hand the torque that can be transmitted through the clutch arrangement and thus possibly the actuation pressure under the boundary condition of sufficient Transmission of the torque of the drive unit can be minimized.

Through the described tracking or adjustment of Clutch actuation based on the micro slip does not require special Sensors for the detection of the engine torque and the clutch torque to be provided, which is generally not the case in a motor vehicle be available. Also, the engine torque is one Engine control unit is usually only transmitted relatively imprecisely. Furthermore, the Relationship between a clutch torque determining Actuation size, such as the actuation pressure, and the moment only relative inaccurately known, moreover changing over the lifetime and of dependent on many parameters. The further training proposal lies Understanding that absolute knowledge of the transmitted moment is not necessary, but that it is only important that this Coupling torque and the torque of the drive unit (engine torque) are in equilibrium with each other. Is the clutch torque greater than the moment of the drive unit, so it will Transfer the engine torque safely, but then the described ones may result Leakage losses due to the higher actuation pressure and corresponding Dead times when disengaging. If the clutch torque is significantly less than the moment of the drive unit, so can the moment of the drive unit would not be transmitted and the speed of the drive unit would increase significantly compared to the transmission input speed. Through the Adjustment of clutch actuation based on micro slip can the moment of the clutch assembly without much technical or computational effort with sufficient accuracy changes of the Moments of the drive unit are tracked.

As a basis for the determination of the micro slip, it is advisable to on the one hand on the speed of the drive unit (in particular Engine speed), which is always available in modern motor vehicles Is available and for example from an engine control unit by a Speed sensor is detected. Another option is instead of Engine speed is a clutch input speed using a corresponding sensor. Furthermore, it will often be useful to have one Transmission input speed sensor for detecting the speed of the To provide the relevant transmission input shaft to directly the differential speed to be able to educate. Another option is the transmission input speed taking into account the current gear ratio from a through detected a transmission output speed sensor Determine transmission output speed value or from the vehicle speed.

It has already been mentioned that the invention proposal in Connection with an actuation of the clutch arrangement in the sense of a Engaging is particularly advantageous, especially if this Actuation in response to a given event, such as an ABS Brake intervention, an anti-slip (ASR) intervention or a driving stability (ESP) intervention takes place and is time-critical.

According to a second aspect of the invention, both in the sense of a Proposed training for the inventive method according to the first aspect as well as in the sense of a completely independent one Proposed invention for the above-mentioned method with reference to the operating state mentioned at the beginning suggested that the different clutch arrangement from the first and second Clutch arrangement is operated slightly in the direction of engagement or in one minor actuation corresponding to the direction of engagement Operating state is maintained such that the clutch assembly a Preparatory state, which is due to slightly stronger actuation in The direction of engagement can be converted into a torque transmission state in which the clutch assembly a not insignificant moment between the drive unit and the transmission can transmit.

As such, it is obvious that the clutch arrangement that is currently no driving torque needs to be transmitted to the transmission, either completely open (especially if on the associated Gearbox input shaft a gearbox is already engaged) or fully engage (for example if there is no gear on the assigned transmission input shaft is inserted). The latter is in the case of a hydraulically operated one Coupling device with hydraulic integrated in the coupling device Slave cylinders, however, for the reasons already mentioned above (Leakage, efficiency) less advantageous, so in itself everything for it speaks, the currently not required clutch assembly completely to disengage (at least if there is currently no gear change to is expected) so that the total leakage is minimized.

However, the complete disengagement results in the disadvantage that at an actuation of the clutch assembly in the sense of engagement approximately in A certain dead time occurs in connection with a gear change because the Friction surfaces of the clutch assembly are first brought together to bring them into mutual frictional engagement. For example in the case of a hydraulically operated clutch arrangement of the The hydraulic slave cylinder is filled to the extent that that by means of a corresponding movement of the piston of the Slave cylinder the air gap of the plate pack is overcome, before which a noteworthy moment (greater than occurring drag torque) can be transferred. Such a filling process of the hydraulic Slave cylinder takes a certain amount of time, for example in the Of the order of 100 ms.

Assuming a hydraulically operated clutch arrangement, so according to the invention proposal, the clutch assembly that is not engaged with a certain hydraulic pressure (which is the holding pressure could be referred to) applied greater than zero. This holding pressure can by a control or computing unit based on Operating parameters or the like (in particular the temperature) to a value are set higher than zero, the pressure is too high (e.g. 2 bar), see above occur due to insufficient clearance of the plate pack Drag torque in the clutch and the situation can occur that with an idle transmission input shaft through this Dragging torque is prevented. is on the other hand, a gear is engaged on the transmission input shaft, so arise undesirable loss of efficiency that reduces efficiency. However, is If the pressure is too low (e.g.> 0.5 bar), the Coupling arrangement in the context of a shift relatively long time Overcoming the clearance is required. It is therefore recommended that an "optimal" Holding pressure according to a compromise between short switching times on the one hand and increased drag torque on the other.

The above considerations regarding hydraulically operated Coupling arrangements of the multi-plate design apply accordingly to others Clutch types, especially dry clutches of the friction disc type. It is therefore generally suggested that the other Coupling arrangement near a grinding point on the release side disruptive to the same or near a point of insertion Towing moments on the release side of the same is kept. Here is it is advantageous if the other clutch arrangement corresponds to one Compromise between a occurring at the clutch assembly minimizing friction or drag torque and a remaining reaction times when actuating the clutch with determining and therefore air gap to be minimized is actuated.

In general, it will be appropriate to in the other clutch assembly Dependence on at least one operating parameter and / or to actuate at least one driving parameter, for example in dependence on the Speed of the drive unit, the transmission input speed, etc. reference taking on wet-running multi-plate clutch assemblies should The temperature of the cooling oil supplied to the plate packs is taken into account because of the viscosity of the oil and therefore that of the fins occurring drag torque decreases for increasing oil temperatures. So it is expedient if the holding pressure already mentioned increases with increasing Oil temperature rises.

The amount of actuation of the other clutch assembly in The direction of engagement can advantageously depend on whether a gear is on the assigned transmission input shaft is inserted or not. in case of a more gear than in the case of none is recommended inserted gangs. In the state of an idling transmission input shaft can be a smaller holding pressure than in the case of one on the Gearbox input shaft gear can be advantageous.

It is proposed as particularly preferred that the other Coupling arrangement in a state where on the other Gearbox input shaft assigned to the clutch arrangement, a gear is engaged Preparing to redistribute the drive torque between the two Gearbox input shafts by operating the opposite direction Clutch arrangements previously operated stronger in the direction of engagement becomes. For example, in the case of hydraulically operated Coupling device a computing unit or the like with the gear engaged Increase holding pressure if it is foreseeable that soon (e.g. 2 seconds) a circuit will be initiated. For example, in the case of an automatic program usually the switching points clearly predetermined or known so that based on the speed of the Drive unit and its course estimated in the past seconds can be when the switching point is reached.

As mentioned, the method can be related to a clutch assembly or clutch assemblies of the NORMALLY OPEN type be applied. However, it is also possible to relate the procedure to a Coupling arrangement or coupling arrangements from the NORMALLY- CLOSED type apply and at least part of the to achieve the advantages mentioned.

Regarding the application of the procedure is mainly, but not exclusively, thought of a coupling device, the at least one integrated in it, the clutch assembly or Coupling arrangements associated with their actuation, in operation with this / this revolving hydraulic slave cylinder, which has a Rotary union on an assigned, stationary in the vehicle arranged hydraulic pressure source is connected. In the Coupling arrangement or the coupling arrangements can (in each case) be a act preferably wet-running multi-plate clutch assembly.

The method according to the first as well as after however, the second aspect is also advantageous in relation to a Coupling arrangement or applicable to coupling arrangements which (each) as preferably dry-running clutch arrangement of the friction disc type is / are executed. For example, in the case of electromotive actuators Dry clutches no leaks. Follow the procedure described the first aspect, especially the one Torque equilibrium detection or the regulation of the differential speed, or / and after the second Aspect, especially the setting of the preparatory state, but can can also be used here to make shifting easier and more advantageous Increase switching speed. Regarding the second aspect, that with dry clutches no significant drag torque occur as soon as the clutch (or the clutch assembly) is opened. One can therefore, according to the invention proposal Keep the clutch assembly close to the grinding point for time when shifting save.

The invention further relates to a drive train, possibly in a Motor vehicle, comprising: a drive unit, possibly in the form of a Internal combustion engine; a transmission with at least one transmission input shaft and at least one transmission output shaft; and one between the Drive unit and the clutch device arranged, possibly Multiple coupling device or double coupling device, for Torque transmission between the drive unit and the transmission; the in In the case of a multiple or double clutch device, one of the first Gearbox input shaft assigned first clutch arrangement and one of the second clutch arrangement assigned to the second transmission input shaft which coupling arrangements are independent of each other can be operated. According to the invention it is proposed that the drive train or at least a control unit is assigned to the coupling device, is set up according to the coupling device according to the method to operate the first or / and the second aspect of the invention. at the coupling arrangement or the coupling arrangements can be (each) around a NORMALLY OPEN type clutch assembly act; however, this is not mandatory. It will in particular (but not exclusively) to a coupling device with at least one in it integrated, the clutch assembly or the clutch assemblies associated with their operation and in operation with this / these rotating hydraulic slave cylinder, which has a Rotary feedthrough on an assigned, stationary arranged in the vehicle hydraulic pressure source is connected. With the clutch arrangement or the coupling arrangements, for example (each) act a preferably wet-running multi-plate clutch assembly. Another possibility is that the clutch arrangement or Coupling arrangements (each) as preferably dry-running Clutch arrangement of the friction disc type is / are.

The invention is described below with reference to the figures Embodiments explained in more detail.

Fig. 1 shows in a schematic block diagram of a motor vehicle clutch and transmission system including a clutch and the transmission associated actuator, the hydraulic pressure medium from a hydraulic pressure medium obtained providing means.

FIG. 2 shows a schematic block diagram of a motor vehicle drive train with a drive unit, a transmission with two coaxially arranged transmission input shafts and a double clutch between the drive unit and the transmission, the actuating device of FIG. 1 being able to be assigned to the double clutch and the transmission.

Fig. 3 shows an electronic by corresponding components or programmatically implemented control loop for setting a micro slip in a schematically shows a driving torque from the drive unit to the transmission clutch transmitting assembly, such as a currently active coupling arrangement of the double clutch of FIG. 2.

Fig. 1 shows an example of a system to which the present invention is applicable. An actuation device 14 is assigned to a clutch 10 designed as a double clutch and a transmission 12 of a motor vehicle drive train, which actuates the clutch (or its clutch arrangements) and the transmission hydraulically or on the basis of hydraulic medium supplied by the actuation device. For this purpose, the actuation device is controlled by a transmission and clutch control device TCU 16 , which in turn is connected to an engine control unit ECU 18 , in order to receive or exchange important data (such as temperatures, speeds, etc.). The TCU can also be connected to other components of the motor vehicle or drive train, in particular those components which are relevant for clutch and transmission actuation. The TCU includes a program-controlled microprocessor that controls the operation of the actuator 14 . The actuating device contains, for example, electromagnetic valves (control and regulating valves) which serve to act upon hydraulic actuating cylinders of the clutch and the transmission with hydraulic pressure medium. Furthermore, the actuating device can contain sensors that detect current states of the clutch and the transmission.

The actuating device 14 receives hydraulic pressure medium from a pneumatic pressure accumulator 20 , which is filled with hydraulic medium by a pump 22 from a reservoir 24 . For this purpose, the pump, which is preferably driven electrically, is switched on and off by the TCU. In order to prevent hydraulic medium from flowing back from the pressure accumulator 20 into the reservoir 24 , a check valve 26 is provided. The current storage pressure is detected by a pressure sensor 28 , and the. TCU controls the pump 22 based, among other things, on the pressure signal supplied by the sensor 28 .

The double clutch can be wet-running Multi-plate clutch with a first multi-plate clutch arrangement and a second Act multi-plate clutch assembly, such as from the DE 100 04 179 A1 is known.

Fig. 2 shows a section of the drive train of a motor vehicle. An internal combustion engine 30 serving as a drive unit, to which an engine speed sensor 32 is assigned, transmits the engine torque to the double clutch 10 via a torsional vibration damper arrangement 34 , which is designed, for example, as a two-mass flywheel and to which a speed sensor 36 can be assigned on the secondary side, from which the transmitted torque, depending on the engagement state of the two clutch arrangements 10 a, 10 b, via a first, radially outer transmission input shaft 38 designed as a hollow shaft and / or via a second transmission input shaft 40 extending through it into the transmission 12 . The secondary mass of the two-mass flywheel can be identical to a driver plate or a housing part of the clutch 10 . A separate speed sensor 42 or 44 can advantageously be assigned to each of the two transmission input shafts in order to be able to detect the transmission input speed for the relevant transmission input shaft. As an alternative or in addition, a speed sensor 48 assigned to the transmission output, for example the transmission output shaft 46 , can be provided.

A current slip state of the double clutch 10 can be characterized by the differential speed that occurs at the torque-transmitted clutch arrangement. For example, the difference between the speed detected by sensor 32 or 36 and the speed detected by sensor 42 or 44 or - taking into account the current gear ratio - detected by sensor 48 and used as a measure of the clutch slip.

According to an aspect of the invention (first aspect) it is provided that the currently a drive torque from the drive unit via the transmission transmitting to the driven wheels of the motor vehicle Coupling arrangement is operated as far as possible or in one is operated such that the transmissible by it Moment exactly one moment given by the drive unit corresponds to or is slightly smaller than this. One is particularly preferred such design of this proposal for the invention, which at the a slight set slip (micro slip) is set and held, preferably a regulation of this Slip is provided.

Such a control of the clutch slip can take place in the manner illustrated in FIG. 3, wherein either a control circuit formed from analog and / or digital electronic components can be provided or the control can be implemented purely in software, for example in the form of corresponding control routines running in the TCU ,

The regulation is based on the formation of a differential speed Δn by a differential element 80, for example from the engine speed n _M and the speed of the relevant transmission input shaft n _GE . This differential speed is compared in a differential element 82 with a target differential value, which is either predetermined constantly by an encoder 84 or is variably predetermined by an encoder 86 depending on other variables. The switch 88 symbolizes the possibility of switching between a constantly predetermined setpoint and a variable setpoint.

A .DELTA.n controller 90 calculates from the difference provided by the member 82 difference value a target value for the clutch actuator, in this case a target operating pressure p _{is intended} for the hydraulic actuation of the couplings lung arrangement by means of a hydraulic slave cylinder. _To p This target value is in a differential element 92 with an actual pressure value p _is compared, which is provided by an actuating pressure detecting pressure sensor 94th A pressure regulator 96 uses the difference value provided by the differential element 92 to calculate a desired value i _soll for the valve current to be supplied _to a hydraulic valve 98 . A dither signal (for example a square-wave signal of small amplitude) is superimposed on this setpoint value by means of an adder 100 , which serves to ensure that the valve does not come into a state of sticking, ie that the valve does not "fall asleep". The current setpoint value superimposed with the dither signal is compared in a differential element 102 with an actual value i _ist , which _is detected by means of a current sensor and which represents the current actually acting on the valve. A current controller 104 ensures that the actual value is approximated to or corresponds to the target value, which ultimately ensures that the target slip is set or maintained by means of the actuation pressure supplied to the clutch 10 or the active clutch arrangement.

As a result of the actuation of the clutch arrangement described, in the case of a hydraulically actuated clutch of the NORMALIZING OPEN type, the hydraulic pressure is kept at a minimum value which is just sufficient to transmit the engine torque to the transmission. Leakages on a rotary leadthrough, via which a respective hydraulic slave cylinder integrated in the clutch is connected to a pressure source arranged in a stationary manner in the vehicle, in particular, for example, to the actuating device 14 in FIG. 1, are thereby avoided or at least minimized, and it can therefore be a comparative one simple and therefore inexpensive rotating union can be used. Another advantage is that a more complex rotating union, which ensures a better seal, would result in increased friction on the sealing surfaces and thus greater wear.

Due to the reduced leakage, the pressure pump 22 or its motor can be designed for an overall shorter duty cycle, which in turn results in cost advantages. Furthermore, by adjusting the actuation pressure in accordance with the engine torque, the clutch arrangement can be actuated in the disengaging direction quickly, namely while avoiding dead times, for example in connection with an ABS / ASR / ESP intervention.

It was assumed above that the clutch 10 is a double clutch. The clutch 10 could also be a single clutch with only one clutch arrangement. In this case, the transmission would be a simple transmission with a transmission input shaft. For a drive train constructed in this way, the same advantages are obtained as explained above with reference to the drive train with the double clutch.

A further aspect of the invention is explained below using the exemplary embodiment. This aspect of the invention relates specifically to the clutch 10 of the arrangement according to FIG. 1 or of the drive train according to FIG. 2 designed as a double or multiple clutch.

According to this further aspect (second aspect) of the invention, the clutch arrangement which does not currently transmit any drive torque is not completely disengaged and is not completely engaged, as this should appear to be advantageous per se. The clutch arrangement of the double clutch 10 , which is currently not transmitting any torque, is instead actuated slightly in the engagement direction, so that a preparatory state for the clutch arrangement is set, from which it only requires a slight actuation in the engagement direction that a noteworthy torque transmission via this clutch arrangement begins. For example, a point of a weakly starting drag torque or a point in close proximity to a grinding point of the clutch arrangement is set. This results in the advantage that the clutch arrangement can be actuated quickly in the engaging direction with almost instantaneous torque transmission, that is to say there is no significant dead time until the moment transmission begins.

The corresponding activation, possibly open-loop or closed-loop control, of the currently inactive clutch arrangement can be brought about by corresponding functionalities of the control unit TCU 16 , which are preferably implemented in terms of programming.

According to a preferred embodiment, the preparatory state is set by controlled actuation of the clutch arrangement in question, it being possible to use characteristic maps or characteristic data which can be stored in a corresponding memory, for example of the control unit 16 , and to activate and deactivate the clutch arrangement Disengagement data could be generated. It is particularly contemplated that in the event of a slipping actuation of the clutch arrangement according to the first aspect of the invention, data obtained during this actuation, in particular the actual actuation pressures to be set in the slipped state, are evaluated in conjunction with characteristic data of the clutch and the actuation system, in order to derive from this _to determine a target pressure p, which is to be applied if is to be set for the coupling arrangement of the preparation state. Correction terms and correction factors can be provided to take into account, for example, an instantaneous oil temperature and the like (or in general operating states or operating parameters of the drive train).

In Fig. 3 the possibility of the controlled actuation of the other currently non-torque-transmitting coupling arrangement is based on a nominal pressure p _{is intended to} schematically indicated. A reference value generator 120 outputs a pressure setpoint P _set out, preferably taking into account various operating and driving parameters, also the temperature of the pressure oil and / or a temperature of a heat removal by the blades of a multi-disk coupling arrangement possibly serving cooling oil. The setpoint value of the actuation pressure is compared in a differential element 122 with an actual value pest, which can be detected by means of a pressure sensor. The actual value can be set in the manner described in connection with the components or functions 96 , 100 , 102 , 104 , 98 and 94 . The box B drawn in dashed lines in FIG. 3 can thus represent functions or circuit components which correspond to the function blocks or circuit components within the dashed box A. Of the two clutch arrangements of a double clutch, one can be operated (apart from special situations and switching processes) in a controlled manner via the components or functions of box A with regard to their slip, and the other via the components or functions of box B with regard to a target which results in the preparation state -Actuation pressure can be operated controlled.

Claims (21)

1. A method for operating a drive train belonging to a motor vehicle, which has:
a drive unit ( 30 ), possibly in the form of an internal combustion engine ( 30 );
a transmission ( 12 ) with at least two transmission input shafts ( 38 , 40 ) and at least one transmission output shaft ( 46 ), a first transmission input shaft being assigned to at least a first gear of the transmission and a second transmission input shaft being assigned to at least a second gear of the transmission;
a multiple clutch device, possibly double clutch device ( 10 ), arranged between the drive unit and the transmission, for torque transmission between the drive unit and the transmission, the first clutch arrangement ( 10 a) assigned to the first transmission input shaft and a second clutch arrangement assigned to the second transmission input shaft (b 10), wherein the two coupling assemblies are independently operable;
characterized by
that in an operating state in which i) a gear from the first and second gear is engaged, ii) a drive torque from the drive unit ( 30 ) via the clutch arrangement assigned to the engaged gear from the first and the second clutch arrangement to the relevant transmission input shaft and from this the transmission ( 12 ) is transmitted to the driven wheels of the motor vehicle, iii) any shifting of the transmission between two or more gears including a coordinated actuation of the clutch device ( 10 ) has been completed and iv) currently no shifting of the transmission between two or more Gears is present including an actuation of the clutch device which is coordinated therewith, the clutch arrangement which transmits the drive torque is actuated or is held in such an actuation state that the torque which can be transmitted corresponds exactly to a torque output by the drive unit ( 30 ) is not or slightly smaller than this. 2. Method for operating a drive train belonging to a motor vehicle, which has:
a drive unit ( 10 ), possibly in the form of an internal combustion engine ( 30 );
a transmission ( 12 ) with at least one transmission input shaft ( 38 , 40 ) and at least one transmission output shaft ( 46 );
a coupling device ( 10 ) arranged between the drive unit and the transmission for torque transmission between the drive unit and the transmission;
characterized,
that in an operating state in which i) a gear of the transmission is engaged, ii) a drive torque from the drive unit ( 30 ) via a clutch arrangement of the clutch device assigned to the engaged gear to an assigned transmission input shaft and from this via the transmission ( 12 ) to the driven wheels of the motor vehicle is transmitted, iii) any shifting of the transmission between two or more gears, including actuation of the clutch device coordinated therewith, and iv) currently no shifting of the transmission between two or more gears, including actuation of the clutch device coordinated therewith ( 10 ) is applied, the clutch arrangement transmitting the drive torque is actuated or is held in such an actuation state that the torque it transmits corresponds exactly to a torque given by the drive unit ( 30 ) or is slightly less a ls this is. 3. The method according to claim 1 or 2, characterized in that that of the torque transmitting clutch assembly transmitted torque slightly less than that from the drive unit is given moment and that a resultant Micro slip on this clutch assembly by appropriate Actuation of the clutch assembly is kept in a target range. 4. The method according to claim 3, characterized by a regulated Actuation of the torque transmitting clutch assembly Basis of a characterizing the micro slip Differential speed and a predetermined or depending on at least an operating parameter and / or at least one driving parameter determined target differential speed. 5. The method according to any one of claims 1 to 4, characterized characterized in that the torque transmitting clutch assembly in Response to a given event, such as a ÄBS brake intervention, an anti-slip (ASR) intervention or a driving stability (ESP) intervention, in the sense of disengagement. 6. The method according to any one of claims 1, 3 to 5, characterized characterized in that the other clutch assembly from the first and the second clutch arrangement slightly in the direction of engagement is operated or in a minor operation in Corresponding state of engagement is maintained, such that the clutch assembly is in a preparatory state occupies by slightly more pressure in The direction of engagement can be converted into a torque transmission state in which the clutch assembly a not insignificant moment between the drive unit and the transmission can transmit. 7. Method for operating a drive train belonging to a motor vehicle, which has:
a drive unit ( 30 ), possibly in the form of an internal combustion engine ( 30 );
a transmission ( 12 ) with at least two transmission input shafts ( 38 , 40 ) and at least one transmission output shaft, a first transmission input shaft being assigned to at least a first gear of the transmission and a second transmission input shaft being assigned to at least a second gear of the transmission;
a multiple clutch device, possibly double clutch device ( 10 ), arranged between the drive unit and the transmission, for torque transmission between the drive unit and the transmission, the first clutch arrangement ( 10 a) assigned to the first transmission input shaft and a second clutch arrangement assigned to the second transmission input shaft (b 10), wherein the two coupling assemblies are independently operable;
characterized,
that in an operating state in which i) a gear from the first and second gear is engaged, ii) a drive torque from the drive unit ( 30 ) via the clutch arrangement assigned to the engaged gear from the first and the second clutch arrangement to the relevant transmission input shaft and from this the transmission ( 12 ) is transmitted to the driven wheels of the motor vehicle, iii) any shifting of the transmission between two or more gears, including a coordinated actuation of the clutch device, and iv) currently no shifting of the transmission between two or more gears, including one there is a coordinated actuation of the clutch device ( 10 ), the other clutch arrangement is actuated slightly in the engagement direction by the first and the second clutch arrangement or is held in an actuation state corresponding to a slight actuation in the engagement direction , such that the clutch arrangement assumes a preparatory state which can be converted into a torque transmission state by slightly more actuation in the engagement direction, in which the clutch arrangement can transmit a not insignificant torque between the drive unit ( 30 ) and the transmission ( 12 ). 8. The method according to claim 6 or 7, characterized in that the other clutch assembly near a grinding point on the release side of the same or near a point of the Use of disruptive drag torque on the release side the same is held. 9. The method according to claim 8, characterized in that the other coupling arrangement according to a compromise between a occurring on the clutch assembly, per se minimizing friction or drag torque and a remaining, Response times when actuating the clutch with determining and therefore air gap to be minimized is actuated. 10. The method according to any one of claims 6 to 9, characterized characterized in that the other clutch arrangement depending on at least one operating parameter and / or at least one Driving parameters is operated. 11. The method according to claim 10, characterized in that the Strength of actuation of the other clutch arrangement in Direction of engagement depends on whether a gear is assigned to the Transmission input shaft is inserted, being in the case of an inserted Gangs a stronger actuation than in the case of no gear engaged is provided. 12. The method according to any one of claims 6 to 11, characterized characterized in that the other clutch assembly in a state in the on the assigned to the other clutch assembly Gearbox input shaft is in gear to prepare a gear Redistribution of the drive torque between the two Gearbox input shafts by operating the opposite direction Clutch arrangements, more in advance in the direction of engagement is operated. 13. The method according to any one of claims 1 to 12, characterized in that it is used in relation to a clutch arrangement or to clutch arrangements ( 10 a, 10 b) of the NORMALERWEISE-OPEN type. 14. The method according to any one of claims 1 to 13, characterized in that it is used in relation to a coupling device ( 10 ) with at least one integrated therein, the coupling arrangement or the coupling arrangements ( 10 a, 10 b) for their actuation and in operation with this / these rotating hydraulic slave cylinder, which is connected via a rotary feedthrough to an associated hydraulic pressure source arranged in the vehicle. 15. The method according to any one of claims 1 to 14, characterized in that it is applied in relation to a clutch arrangement or to clutch arrangements ( 10 a, 10 b) of the preferably wet-running multi-plate clutch type. 16. The method according to any one of claims 1 to 14, characterized characterized in that it is related to a clutch assembly or Coupling arrangements of preferably dry-running Friction disc type is applied. 17. Drive train, possibly in a motor vehicle, comprising:
a drive unit ( 30 ), possibly in the form of an internal combustion engine ( 30 );
a transmission ( 12 ) with at least one transmission input shaft ( 38 , 40 ) and at least one transmission output shaft ( 46 );
a coupling device, possibly a multiple coupling device or a double coupling device ( 10 ), arranged between the drive unit ( 30 ) and the transmission ( 12 ), for torque transmission between the drive unit and the transmission, which in the case of a multiple or double coupling device is a first transmission input shaft has assigned first clutch arrangement ( 10 a) and a second transmission input shaft assigned second clutch arrangement ( 10 b), which clutch arrangements ( 10 a, 10 b) can be actuated independently of one another;
characterized by a control unit ( 16 ) assigned to the drive train or at least to the clutch device ( 10 ), which is set up to actuate the clutch device according to the method according to one of the preceding claims. 18. Drive train according to claim 17, characterized by a clutch arrangement or clutch arrangements ( 10 a, 10 b) of the NORMALERWEISE-OPEN type. 19. The drive train according to claim 17 or 18, characterized by a coupling device ( 10 ) with at least one integrated therein, the coupling arrangement or the coupling arrangements ( 10 a, 10 b) associated with their actuation and in operation with this / these rotating hydraulic slave cylinder , which is connected via a rotary feedthrough to an associated hydraulic pressure source arranged in the vehicle. 20. Drive train according to one of claims 17 to 19, characterized by a clutch arrangement or clutch arrangements ( 10 a, 10 b) of the preferably wet-running multi-plate clutch type. 21. Drive train according to one of claims 17 to 20, characterized by a coupling arrangement or coupling arrangements of the preferably dry-running type of friction disc.