DE19853824A1 - Automated motor vehicle drive train has parallel force transfer paths; second force transfer path transfers torque to drive shaft during force transfer interruption in first transfer path - Google Patents

Abstract

The motor vehicle drive train has a discrete gearbox (14) with a number of gears and parallel force transfer paths (16,18) with associated main couplings (K1,K2) and a control arrangement (15) that controls the gearbox and couplings for a first type of gear change so that the torque to be transferred to a drive shaft (25) under load from one of the force transfer paths is fully transferred to the other path. For a second type of change the torque is transferred from one gear in the first path to one in the second path; during the interruption of traction force in the first path (16), the second path (18) transfers a torque to the drive shaft. An Independent claim is also included for a method of controlling a motor vehicle drive train.

Description

The present invention relates to an automatable motor vehicle drive train with

• - A step transmission with a plurality N of gears, the a first and a second parallel force has branch of support,  
• - A first and a second main clutch that the assigned to the first or the second power transmission branch are and
• - Control means, the main clutches and the steps gearboxes in a first type of gear change control that to be transmitted to an output shaft Torque under load from one of the two Power transmission branches completely on the other Power transmission branch is passed.

The invention further relates to a method for controlling a drive train of a motor vehicle, the drive train having:

• - A step transmission with a plurality N of forward gears, a first and a second parallel Power transmission branch includes, and
• - A first and a second main clutch that the first or are assigned to the second power transmission branch,

the main clutches and the stepped transmission at one first type of gear change can be controlled so that the torque to be transmitted to an output shaft under load from one of the two power transmission branches completely to the other power transmission branch is passed.

Such a motor vehicle drive train and such Control methods are known from DE-C-38 12 327.  

A distinction is made between so-called Powershift transmissions on the one hand and transmissions with train power interruption on the other hand. Powershift transmissions are usually as a planetary gear with upstream hydro dynamic converter trained. By operating clutches and brakes for the individual elements of the planetary gear the gears are shifted in time overlap, so that there is no interruption in traction during a gear change occurs from the engine to the wheels of the motor vehicle.

In the case of gearboxes with traction interruption, for example conventional motor vehicle gearboxes in countershaft construction, on the other hand, the flow of force becomes greater with every gear change first separated in the old gear and then again in the new gear closed, so that a sub during gear change breaking of the tensile force occurs. This interruption is over noticeable in train operation as a shift jerk, especially when Upshifting from low to higher gears can be annoying when the vehicle "nods" as a result of the traction interruption.

As part of the automation of such gearboxes An attempt was made to interrupt the tractive force, thereby causing the shift jolt to reduce that you have two parallel disconnect clutches (Main couplings) provides that with a first or a second group of courses are connectable. In such, Ge usually referred to as a dual clutch transmission Can drive gear changes in train operation without any tractive effort interruption can be carried out because in time over cutting a corridor of a first group using, for example one of the two separating clutches designed and simultaneously another gear from the second clutch  second group is inserted, such as from the initially mentioned DE-C-38 12 327 is known.

Due to the parallelism of their construction, double clutch transmissions generally require that at least the shaft connected to one of the two clutches is designed as a hollow shaft. In order to ensure that there is no interruption in tractive power in all gearshifts, at least two wheel sets must be mounted on the hollow shaft, for example gears 2 and 4 , whereas gears 1 , 3 , 5 are assigned to a central shaft extending through the hollow shaft. Such hollow shaft designs are comparatively expensive. In addition, such dual clutch transmissions are relatively large.

Another step transmission is known from DE-A-44 01 812. This also has two structurally united on the input side Friction clutches. One of the two friction clutches is one with a conventional transmission input shaft also essentially conventional step transmission in front connected construction. The other clutch is over a short hollow shaft section with one on the gearbox input shaft mounted idler gear for the highest gear ver bound.

The highest, in the proposed transmission, the sixth Ge gear, is thus leads out as a selectable gear stage in order to be able to perform gear changes with a reduced shift jerk. It is therefore not a "real" dual clutch transmission in the sense described above, although here too two clutches are structurally combined in a compact design. One of the two clutches is only connected to the highest gear of this multi-stage transmission. It is explained in this document that this highest gear should be able to be engaged via the assigned clutch. In other words, for example, when changing gear 1-2 , 2-3 etc., which all take place on the power transmission branch assigned to the other clutch, the highest gear is switched to the output shaft of the transmission via the second clutch in the period of the interruption of tractive power. Here, however, the shift jerk otherwise occurring due to the interruption of the tractive force in the first power transmission branch is not completely avoided, but is alleviated at best.

Another transmission with bridging traction is out of the EP-B-0 173 117 is known. There is no separator on this gear clutch between the motor vehicle engine and the step transmission switched. The highest gear is one for bridging the tractive force assigned fluid-operated friction clutch.

Finally, from DE-C-195 48 622 a traction under gear change gearbox for power vehicles known. This gearbox is a Triple clutch transmission. In addition to a friction clutch, the is arranged between the engine output shaft and the transmission a dog clutch and a synchronizer clutch are provided. The Construction is extremely complex, especially on due to the three different couplings. The fact that the engine output shaft in certain operating states a claw coupling that is difficult to open under load lets, is connected to the transmission input shaft, provides a The required installation space of this Ge drive is also extremely high.  

Against this background of the invention on gift is a motor vehicle powertrain type mentioned above or an associated method to that effect to further develop that with the least possible design effort minimal loss of comfort due to switching jolts occur.

This object is achieved in the drive train according to the invention mentioned in that the second power transmission branch is assigned to one or more of the gears 2 to N-1 of the N-speed step transmission, the control means the main clutches and the step transmission in a second Control type of gear change further such that the torque to be transmitted is transferred from one gear of the first power transmission branch to another gear of the first power transmission branch and that for the period of an interruption in traction in the first power transmission branch, the second power transmission branch transmits a torque to the output shaft .

In the control method mentioned at the outset, this object is further achieved according to the invention in that the main clutches and the step transmission are also controlled in a second type of gear change in such a way that the torque to be transmitted is transferred from one gear of the first power transmission branch to another gear of the first power transmission branch and that for the period of a traction interruption in the first power transmission branch, the second power transmission branch transmits a torque to the output shaft by means of one of the gears 2 to N-1.

The object underlying the invention is based on this Way completely solved.

By the measure that gearboxes of the motor vehicle drive train to be interpreted so that not all gear changes are made in the manner of a "real" double clutch transmission, the design effort is considerably reduced. In particular, a hollow shaft can be made extremely short. The idea of not bridging traction in the second type of gear change not with the highest (Nth gear) of the multi-speed transmission, but with at least one of the gears 2 to N-1, will result in a noticeably greater alleviation when changing gears in the gears below Shift jerk it is sufficient as a bridging traction by means of the highest gear. Because in the highest gear the slightest moment is transmitted.

With a shift change, for example from first to second gear, the torque drops relatively strongly despite a tractive force lock-up with only the highest gear, whereas with a tractive force lock-up by means of one of the gears 2 to N-1, a larger torque is applied to the output shaft of the gearbox and thus the wheels of the motor vehicle can be directed.

The inventors have recognized that through this Measure according to the invention has the disadvantage that at a Gear change above the highest gear of the second power transmission no bridging force can, is in no way serious in practice. Because with one Gear change from, for example, fifth to sixth gear  the jump in torque to be bridged is comparative anyway as low, so that the driver does not have the essential comfort impairing shift jerk senses. One becomes subjective Driver of the motor vehicle the disadvantage of the lack of train power bridging in the higher gears therefore hardly felt, the advantage of better traction bridging in lower gears on the other hand, felt enormous.

In addition, if not only the highest gear is assigned to the second power transmission branch, but one of the gears 2 to N-1, at least two different gear changes can be carried out in accordance with the first type. If, for example, the N-1 th gear is assigned to the second power transmission branch, both the gear change from N-2 to N-1 and the gear change from N-1 to N can be carried out according to the first gear change type, in which the torque to be transmitted is fully transferred under load from one of the two power transmission branches to the other power transmission branch.

It is understood that currently a transmission with N gears usual 5-speed and 6-speed gearboxes can be understood, but of course also 3-speed or 4-speed gearbox as well 7-speed, 8-speed and transmission with even more gears.

There are only comparatively few clutches during one automatic control of the transmission can be switched. It comparatively little space is required, both in axial as well as radial.  

The parallel main clutches are connected to the motor vehicle the powertrain for the first type of gear change too Thrust circuits can be carried out under load. The start is also possible with two clutches at the same time.

Removing or laying out a gear when changing gears is not critical and not relevant to time; it's not necessary, provide a separate freewheel for this purpose.

Furthermore, the diameters of the two main clutches can be very run great.

The drive train is preferably also characterized thereby from that over a third type of gear change bearing torque from a gear of the first force transmission branch to another gear of the same force is transferred and that for the period of one Traction power interruption in the first power transmission branch of the other power transmission branch no torque on the output wave transmits.

This measure allows the drive train to continue constructionally be simplified. Understands based on the above themselves that such gear changes of the third kind with traction interruption preferably take place in the upper corridors, especially when changing gears to the highest (Nth) gear. Because with such gear changes the leader of the Motor vehicle almost not notice an interruption in traction bar.  

According to a further preferred embodiment, the assigned a single gear to the second power transmission branch.

With this measure, one can be featured in the multi-step transmission see hollow shaft are particularly short.

It is particularly preferred if the only gear is the N-1. Gear is.

In this embodiment there are at least two on the one hand Switching operations of the first type possible, namely from N-2 to N-1 and from N-1 to N. Furthermore, there is none when shifting up Gear change in the area of forward gears, the one without a train bridging must take place.

According to an alternative preferred embodiment, the only gear of the N-2. Gear.

In this embodiment, it is not possible to pull a train power bridging from the N-1. To reach gear in the Nth gear. For that it is with bridging traction in the course of gear change of the second type by means of the N-2. Ganges delivered Torque greater due to the higher ratio of the N-2. Ganges compared to the N-1. Gear.

According to an alternative preferred embodiment, the assigned two gears to the second power transmission branch.

Advantageously, there are more gears in this embodiment change of the first type. Especially if the stepped transmission is provided with three shafts and the two  Gears of the second power transmission branch on two output waves are distributed, is also a short hollow shaft construction possible.

It is particularly preferred if one of the two courses of the second power transmission branch of the N-1. Gear of N gear Stepped transmission is.

This ensures that this alternative too Embodiment when shifting up, no gear change without train bridging must take place.

It is also particularly preferred if the two courses of the second power transmission branch do not follow one another.

This ensures that at least four gear changes the applied torque completely from one Power transmission branch to the other power transmission branch is handed over, i.e. four gear changes of the first kind can take place.

According to a further preferred embodiment, the aisle or the gears of the second power transmission branch a wheel Assigned set that is adjacent to one of the main coupling lungs.

This embodiment ensures that one of the second Hollow shaft assigned to the transmission branch is extraordinary can be made short or the drive train at structural union of the wheelset with the associated one Main clutch can be designed without a hollow shaft.  

Furthermore, according to a further embodiment, it is preferred if the step transmission for engaging and disengaging at least one of the gears that have a higher gear ratio sit as the lowest, the second power transmission branch assigned gear, a non-synchronized positive Has clutch.

Such clutches, in the following short claw clutch tion are much cheaper and be require less space than clutches with one Synchronizer unit. The speed adjustment for switching such Unsynchronized dog clutches can be used with the Drive train through suitable control measures of the main clutch lungs take place. With some gear changes it can turn number adjustment also influences the downforce Torque of the motor vehicle engine desired or even not be agile.

It is further preferred if the two main clutches are adjacent are arranged to each other.

Due to the adjacent arrangement, in particular in the form of a structural union, the two main couplings of the An drive train can be realized comparatively inexpensively. Furthermore, the control of the two main clutches is easier.

In the method according to the invention, it is particularly preferred if in the second type of gear change when shifting up in Train operation first the first main clutch is opened, while at about the same time the second main coupling to rotate moment transfer is closed, and if after laying out  of the previous gear of the first power transmission branch second main clutch as long and / or as far as closed remains in sync until in the first power transmission branch speed of the gear to be engaged has been reached.

Through this preferred embodiment of the invention The procedure can be carried out for the gears that follow the second type of Gear changes are switched, synchro units dispensed with be tested.

This is especially true if the procedure is also so stalten is that in the second type of gear change when Downshift first opened the first main clutch becomes, while at the same time the second main clutch for Torque transfer is closed, and that after laying out the previous gear of the first power transmission branch next the first main clutch is closed again and the second main clutch as long and / or as far as closed remains in sync until in the first power transmission branch speed of the gear to be engaged has been reached.

Overall, the motor vehicle Drive train and the inventive method still note the following. If in the present context of the closing of a clutch, in particular one of the two Main Couplings is spoken, this can vary depending on Context, a grinding or a rotationally entraining Mean activity. It is particularly understood that at Gear change of the second type the respective main clutch is typically operated by grinding.  

Furthermore, gear changes of the third type when shifting up with Double clutch or when switching down with intermediate gas. These types of actuation of the main clutches should also be of the terms used here to close or open the Main clutches may be included. It goes without saying that The automation components not only influence this the drive train but also on the motor vehicle engine have to take. Therefore, it is also understood that the in the Use gears to shift gears in and out interlocking clutches of any type can, because with suitable control of the drive train at least when changing gears of the second and third types all synchronization processes via the main clutches and if necessary, the vehicle engine can take place. Gear change the first Kind preferably affect the upper corridors. With these are separate synchronous units not assigned to the idler gears indispensable.

Further advantages result from the description and the at added drawing.

It is understood that the above and the following standing features to be explained not only in each specified combination, but also in other combinations or can be used alone, without the scope of to leave the present invention.

Embodiments of the invention are in the drawing are shown and are described in more detail in the following description explained. Show it:

Fig. 1 to 7 different embodiments of he inventive motor vehicle drive strands;

FIG. 1a to 7a state tables of the respective clutches of the drive trains of Figures 1 to 7.

8 is a diagram of output torque of the drive train over time during a gear change of the first type. and

Fig. 9 is a diagram of the output torque of the drive train over time in a gear change of the second type.

In Fig. 1, a first embodiment of a motor vehicle drive train according to the Invention is shown generally at 10 .

The drive train 10 comprises a disconnect clutch arrangement 12 , a step transmission 14 and control means 15 .

The control means 15 are used to control the clutch assembly 12 and the step transmission 14 and can be designed as a separate control unit or as part of a superordinate control unit of the motor vehicle.

The step transmission 14 comprises a first power transmission branch 16 and a second power transmission branch 18th

The clutch assembly 12 includes two main or clutch clutches K1, K2. The main clutch K1 connects an output shaft 22 of a motor vehicle engine with an input shaft of the step transmission 14 , which is designed as a hollow shaft 24 . The main clutch K2 is arranged parallel to the main clutch K1 and connects the output shaft 22 to a central transmission input shaft 20 running through the hollow shaft 24 .

The transmission input shaft 20 represents the start of the second power transmission branch 18. The hollow shaft 24 represents the start of the first power transmission branch 16 .

The two parallel power transmission branches 16 , 18 run parallel to one another in the step transmission 14 and are finally coupled to an output shaft 25 of the step transmission 14 . The transmission input shaft 20 is integrally formed with the output shaft 25 and extends through the entire multi-stage transmission 14th The power flow runs in the first power transmission branch 16 from the hollow shaft 24 to a gear set 26 formed as a constant via a countershaft 28 of the step transmission 14 to one of a plurality of gear sets 30-36 , 38 , 40 . The wheel sets 30-36 , 38 , 40 can each be coupled to the central shaft 20 of the multi-stage transmission 14 and thus to the output shaft 25 by means of non-synchronized clutches KK1, KK2, KK3 and KK4.

The wheel set 26 is arranged directly adjacent to the main clutch K1 assigned to the hollow shaft 24 , so that the hollow shaft 24 can be made comparatively short.

On the gear set 26 follow in the output direction of the step transmission 14, the gear set 38 for the sixth gear, the gear set 36 for the fourth gear, the gear set 34 for the third gear, the gear set 32 for the second gear, the gear set 30 for the first gear and finally the gear set 40 for the reverse gear of the step transmission 14 . In this six-speed gearbox 14 , the fifth gear is formed as a direct gear with a gear ratio of i ₅ = 1 and by means of the main clutch K2 directly on the output shaft 25 of the gearbox 14 .

The wheel set 26 comprises a fixed gear 42 connected to the hollow shaft 24 in a rotationally fixed manner and a fixed gear 44 connected to the countershaft 28 in a rotationally fixed manner. The wheel set 30 for the first gear comprises a fixed gear 46 fixed in rotation on the countershaft 28 and an idler gear 48 rotatably mounted on the central shaft 20 . The wheel sets 32 , 34 , 36 , 38 , 40 each comprise accordingly fixed wheels 50 , 54 , 58 , 66 , 70 , which are rotatably connected to the countershaft 28 , and idler wheels 52 , 56 , 60 , 68 , 72 , which are rotatable the central shaft 20 are mounted.

The dog clutch KK1 is arranged between the gear sets 30 and 40 on the central shaft 20 and serves to connect the idler gear 72 of the reverse gear to the central shaft 20 or to separate it. The dog clutch KK2 is arranged between the wheel sets 30 and 32 and can be coupled to the idler wheels 48 and 52 in order to be able to engage and disengage gears 1 and 2 . The dog clutch KK3 is arranged between the wheel sets 34 and 36 and can be coupled to the idler wheels 56 , 60 in order to be able to engage and disengage the gears 3 and 4 . The claw clutch KK4 is arranged between the gear sets 38 and 26 and can be coupled to the idler gear 68 in order to be able to engage and disengage the sixth gear.

The drive train 10 is suitable for installation in vehicles with a standard drive, ie engine at the front, drive axle at the rear.

A corresponding drive train 10 a for transverse installation in a front-wheel drive vehicle is shown in Fig. 2.

In this drive train 10 a extends with the main clutch K1 connected hollow shaft 24 a through almost the entire GE gear 14 a. Fixed wheels 46 a, 50 a, 54 a, 58 a, 66 a and 70 a of the wheel sets 30 a to 36 a, 38 a, 40 a are arranged on the hollow shaft 24 a in a rotationally fixed manner. The corresponding idler wheels 48 a, 52 a, 56 a, 60 a, 68 a, 72 a are rotatably arranged on a countershaft 28 a. The order of the wheel sets is based on the separating clutch arrangement 12 : 40 a, 30 a, 32 a, 34 a, 36 a, 38 a. Claw clutches KK1 to KK4 are arranged correspondingly as in the drive train 10 of FIG. 1. A central gear shaft 20 a connected to the main clutch K2 extends through the hollow shaft 24 a. A wheel set 37 a for the fifth gear comprises a fixed gear 42 a, which is arranged in a rotationally fixed manner on the central shaft 20 a, namely behind the wheel set 38 a for the sixth gear. The wheel set 37 a comprises a second fixed gear 44 a, which is arranged in a rotationally fixed manner on the countershaft 28 a. The wheelset 37 a is thus designed as a constant.

At the fixed gear 44 a opposite end of the countershaft 28 a is also an output gear 76 rotatably angeord net. The output gear 76 is coupled to a differential 78 ge, which can be of conventional design and delivers the force to a left and a right output shaft 25 l, 25 r, which can be connected, for example, to the left and right front wheels of the motor vehicle.

The operation of the drive train 10 a is identical to that of the drive train 10 .

Another alternative drive train 10 b is shown in Fig. 3 ge. The drive train 10 b includes the clutch assembly 12 and a step transmission 14 b. The step transmission 14 b is structurally similar to the drive train 10 of FIG. 1, in contrast to this, however, only requires three clutch couplings, namely two dog clutches KK1 and KK2 and a synchronized clutch SK1.

In this embodiment, the 4th gear is designed as the direct gear with a gear ratio i ₄ = 1. Accordingly, the 4th gear directly via the main clutch K2, an associated central transmission shaft 20 b with a one piece hereby formed transmission output shaft 25 b ver bindable. The main clutch K1 is connected to a short hollow shaft 24 b. On the hollow shaft 24 b, a fixed gear 42 b of a gear set 26 b is rotatably arranged. The wheel set 26 b is formed as a constant and comprises a further fixed gear 44 b, which is arranged on a countershaft 28 b. Starting from the gear set 26 b, the gear sets 38 b, 37 b, 34 b, 32 b, 30 b and 40 b for the gears 6 , 5 , 3 , 2 , 1 , R follow in the output direction. The idler gears of these gear sets are in each case on the central gear shaft 20 b rotatably mounted. Correspondingly, the fixed gears are fixed on the lay shaft 28 b.

The dog clutch KK1 is arranged between the gear sets 40 b and 30 b and can be connected to the idler gears 48 b or 72 b for the first or reverse gear. The dog clutch KK2 is arranged between the gear sets 32 b and 34 b and can be connected to the idler gears 52 b, 56 b for the second and the third gear. The synchronized clutch SK1 is arranged between the gear sets 37 b and 38 b and can be connected to the idler gears 64 b and 68 b for the fifth and the sixth gear.

The step transmission 14 b is thus shorter overall than the step transmission 14 shown in FIG. 1.

FIG. 4 shows a further drive train 10 c, the mode of operation of which corresponds to that of drive train 10 b, but is designed analogously to drive train 10 a of FIG. 2 for transverse installation in front-wheel drive motor vehicles.

In the drive train 10 c, the second main clutch K2 is connected via a short hollow shaft 24 c to a wheel set 36 c for the fourth gear.

Behind the wheel set 36 c, the wheel sets 38 c, 37 c, 34 c, 32 c, 30 c and 40 c are arranged in this order for gears 6 , 5 , 3 , 2 , 1 and R.

The wheel set 36 c is designed as a constant. The idler wheels 48 c, 52 c, 56 c and 72 c of the gears 1-3 , R are rotatably mounted on the countershaft 28 c. The idler gears 64 c, 68 c for fifth and sixth gear are rotatably mounted on the central shaft 20 c. Correspondingly, the fixed gears 46 c, 50 c, 54 c, 70 c are arranged in a rotationally fixed manner on the central shaft 20 c, the fixed gears 62 c, 66 c, however, on the countershaft 28 c. Before the lay shaft 28 c also carries in the vicinity of the fixed gear 44 c of the gear set 36 c an output gear 76 c, which, like the gear 76 of the transmission 10 a, can be coupled with a differential (not shown) (as in FIG. 2), such as it is indicated schematically at 25 c.

The dog clutches KK1 and KK2 are arranged on the countershaft between the wheel sets 30 c, 40 c and 32 c, 34 c. The claw clutch KK1 can be connected to the idler gears 48 c, 72 c in order to shift the first or the reverse gear. The claw clutch KK2 can be connected to the idler gears 52 c, 56 c to shift the second or the third gear.

The synchronized clutch SK1 is arranged between the gear sets 37 c, 38 c on the central shaft 20 c and can be connected to the idler gears 64 c, 68 c to shift gears 5 or 6 .

In contrast to the embodiment of FIG. 2, the drive train 10 c builds shorter due to the only three clutches of the step transmission 14 c. Furthermore, the hollow shaft 24 c can be made shorter, since the only fixed gear 42 c connected to the hollow shaft 24 c is arranged in the direct vicinity of the second main clutch K2.

During the first power transmission branch 16, 16 a in from Fig. 1 and 2 EMBODIMENTS respective gears 1, 2, 3, 4, 6, R comprises and the second power transmission branch 18, 18 a fifth gear, are in the drive trains 10 b, 10 c each contain the gears 1 , 2 , 3 , 5 , 6 , R in the first power transmission branch 16 b, 16 c, the fourth gear is transmitted via the second power transmission branch 18 b or 18 c.

The drive trains 10 , 10 a, 10 b, 10 c discussed above each comprise - apart from the hollow shaft 24 - two parallel shafts, namely a central transmission shaft 20 and a countershaft 28 . In the following three further embodiments are described, in which two further parallel shafts are provided in addition to a central shaft.

A fifth embodiment of the invention is generally designated 10 d in FIG. 5.

The drive train 10 d includes a separating clutch arrangement 12 , which can be constructed identically to the previous embodiments, and a step transmission 14 d.

A hollow shaft 24 d of the step transmission 14 d is connected to the second main clutch K2. On the hollow shaft 24 d, a fixed gear 42 d (= 58 d, 66 d) is fixed for gears 4 and 6 , which is arranged in the direct vicinity of the second main clutch K2. The central shaft 20 d extends through the hollow shaft 24 d. The following are arranged in this order behind the fixed gear 42 d: a further fixed gear 54 d (= 62 d) for gears 3 and 5 , a fixed gear 50 d for the second gear and a fixed gear 46 d (= 70 d) for the Gears 1 and R.

Parallel to the central shaft 20 d, the step transmission 14 d comprises two countershafts 28 d 'and 28 d''. Arranged on the countershaft 28 d 'are an idler gear 68 d of a gear set 38 d for sixth gear, an idler gear 64 d of a gear set 37 d for fifth gear, an idler gear 52 d of a gear set 32 d for second gear and an idler gear 48 d of a 30 d wheel set for first gear. The idler gears 68 d, 64 d, 52 d, 48 d mesh with the corresponding fixed gears 66 d (= 42 d), 62 d (= 54 d), 50 d, 46 d (= 70 d).

A claw clutch KK1 is arranged on the first countershaft 28 d 'for connection to the idler gears 52 d and 48 d. D 'synchronized clutch SK2 is further arranged that the idler gears 68 d 64 d d, with the countershaft 28' of the countershaft 28 can connect.

Arranged on the second countershaft 28 d ″ are: an idler gear 60 d of a gear set 36 d for fourth gear, an idler gear 56 d of a gear set 34 d for third gear and an idler gear 72 d of a gear set 40 d for reverse gear. The idler gears 60 d, 56 d, 72 d mesh with the respective fixed gears 58 d (= 42 d), 54 d (= 62 d), 70 d (= 46 d) arranged on the central shaft 20 d, but with the latter an intermediate gear, not shown, for reversing the direction of rotation.

On the second countershaft 28 d '' a claw coupling KK2 is also arranged, which can connect the idler gears 72 d or 56 d to the pre-lay shaft 28 d ''. Furthermore, a synchronized clutch SK1 can connect the idler gear 60 d to the countershaft 28 d '' or separate from it.

On the countershafts 28 d ', 28 d''each from a drive gear 76 d' and 76 d '' are also provided. Since this 5 is a schematic developed view in the representation of Fig., Both driven gears 76 may be d ', 76 d''mesh with a ring gear of a differential (as in Fig. 2), as schematically d at 25 is indicated.

A first power transmission branch 16 d comprises gears 1 , 2 , 3 , 5 , R. A second power transmission branch comprises gears 4 , 6 .

The drive train 10 d is particularly suitable for installation in the transverse direction in front-wheel drive vehicles. The drive train builds extremely short due to the three-shaft gear 14 d.

An alternative embodiment of a drive train 10 e with a three-shaft step transmission 14 e is shown in Fig. 6 Darge. The drive train 10 e includes a clutch assembly 12 with two main clutches K1, K2.

The second main clutch K2 is connected via a hollow shaft 24 e with a fixed gear 42 e (e = 54, 62 e) for the gears 3 and 5. FIG. A central shaft 20 e extending through the hollow shaft 24 e carries in this order behind the fixed gear 42 e a fixed gear 58 e (= 66 e) for gears 4 and 6 , a fixed gear 50 e and a fixed gear 46 e (= 70 e ) for gears 1 and R.

The following are provided on a first countershaft 28 e ': idler gears 64 e, 68 e, 52 e, 48 e for gears 5 , 6 , 2 and 1 , with the respective fixed gears 62 e, 66 e, 50 e and 46 e comb. Between the idler gears 48 e and 52 e, a claw clutch KK1 is arranged on the first countershaft 28 e 'in order to connect the corresponding idler gears 48 e, 52 e to the countershaft 28 e' for shifting the first or second gear. A synchronized clutch SK3 is arranged between the idler gears 64 e and 68 e for shifting gears 5 or 6 .

On the second countershaft 28 e ″ are arranged: idler gears 56 e, 60 e, 72 e for gears 3 , 4 and R, with fixed gears 54 e, 58 e, or via an idler gear to reverse the direction of rotation comb the fixed gear 70 e.

The idler gear 56 e is assigned a synchronized clutch SK1 for connecting to or detaching from the second countershaft 28 e ″. A synchronized clutch SK2 is arranged between the idler gears 60 e and 72 e. The clutch SK2 is used to connect either the idler gear 60 e or the idler gear 72 e with the second countershaft 28 e '' or to separate them. Towards the idler gear 72 e, the clutch SK2 is designed as a pure claw clutch. For the speed adjustment with the idler gear 60 e of the gear set 36 e for the fourth gear, the clutch SK2 is equipped with a synchronous unit.

As in the embodiment of FIG. 5, an output gear 76 e 'and 76 e''are provided on the countershafts 28 e' and 28 e '', respectively.

In the drive train 10 e, the gears 1 , 2 , 4 , 6 , R are assigned to the first power transmission branch 16 . The gears 3 and 5 are assigned to the second power transmission branch 18 e.

Due to the two countershafts, the power transmission branches 16 and 18 in the two forms 10 d, 10 e each share two first power transmission branches 16 d ', 16 d''(or 16 e', 16 e '') and two second power transmission branches 18 d ', 18 d''(or 18e ', 18 e '').

A seventh embodiment of a drive train according to the invention is shown in Fig. 7 generally at 10 f. The drive train 10 f includes a clutch assembly 12 which corresponds to that of the previous embodiments and a gears 14 f. The step transmission 14 f is - similar to the embodiment from FIGS . 5 and 6 - equipped with three shafts, of which only one is formed as an output shaft.

A hollow shaft 24 f is connected to the second main clutch K2 and to a fixed gear 42 f of a gear set 36 f for the fourth gear. A hollow gear shaft 20 f extends through the hollow shaft 24 f, which carries the wheels behind the fixed gear 42 f: a fixed gear 46 f (= 70 f) for the first and reverse gear, a fixed gear 50 f for the second gear , a fixed gear 54 f for third gear, an idler gear 64 f for fifth gear and an idler gear 68 f for sixth gear.

On an intermediate shaft 78 parallel to the central shaft 20 f, via which no output torque is output, are mounted: an idler gear 48 f of the gear set 30 f for the first gear, an idler gear 52 f of the gear set 32 f for the second gear and a transfer gear 79 , which meshes with the idler gear 64 f, which is mounted on the central shaft 20 f.

Between the idler gears 48 f, 52 f, a dog clutch KK1 is arranged to connect these idler gears to the intermediate shaft 78 .

The transfer gear 79 is used to transfer a torque transferred from the gear sets 30 f or 32 f to the intermediate shaft 78 by means of the gear set 37 f of the fifth gear on a countershaft 28 f, which has an output gear 76 f, which has a differential (as in Fig. 2) can be coupled, as is indicated schematically at 25 f.

On the countershaft 28 f are arranged: a fixed gear 60 f of the gear set 36 f for the fourth gear, an idler gear 72 f of the gear set 40 f for reverse gear, an idler gear 56 f of the gear set 34 f for third gear, a fixed gear 62 f of the gear set 37 f for the fifth gear and a fixed gear 66 f of the gear set 38 f for the sixth gear.

Between the idler gears 56 f, 72 f, a dog clutch KK2 is arranged on the countershaft 28 f for shifting gears 3 or 5 . A synchronized clutch SK1 is arranged on the central shaft 20 f between the idler gears 64 f and 68 f for shifting gears 5 or 6 .

A first power transmission branch 16 f includes gears 1-3 , 5 , 6 , R. A second power transmission branch 18 f includes 4th gear.

The embodiments of motor vehicle drive trains 10 of FIGS. 1-7 have in common that they add a coupling arrangement 12 with two parallel main clutches K1, K2, which can independently connect two parallel power transmission branches 16 , 18 to a motor output shaft 22 . In this respect, the drive trains 10 correspond to a "real" double clutch transmission. In contrast to such conventional double clutch transmissions, only one gear or two gears is assigned to the second power transmission train, which is connected to the main clutch K2, in the drive trains 10 . The second power transmission branch 18 assigned to parent gears or the second power transmission branch 18 gear are selected from the group of gears 2 - N-1, ie without the highest gear (all execution forms here the sixth gear).

In FIGS. 1a-7a, the state tables of the clutches are each of the drive lines 10-10 f of FIG. 1-7 Darge provides. In these tables, an X in columns K1, K2 means that the respective main clutch is closed. With regard to the clutches KK, SK, the number indicates which gear is currently selected. In the rows of this table not only the respective gears R, 1 are - 6, but also the respective gear shift, that is 1 - 2, 2 - 3, etc. In respect to the main clutches K1, K2 will be understood that in the tables Although it is indicated that either only the main clutch K1 or the main clutch K2 is switched ent. In practice, these two main clutches can of course advantageously be switched to overlap when changing gears.

In general, the tables show that there are three different types of gear changes exist.

In a first type of gear change, the torque is transferred from one gear that is shifted via one of the two clutch clutches to another gear that is shifted via the other of the two clutch clutches. The gear change 4-5 may be mentioned as an example in FIG. 1a. In fourth gear, the main clutch K1 is closed, the torque is transmitted to the output shaft 25 via the first power transmission branch 16 by means of the wheel set 36 . For this purpose, the claw clutch KK3 is connected to the idler gear 60 of the wheel set 36 for the fourth gear, which is also shown in FIG. 1a.

In fifth gear, however, the main clutch K1 is open and only the second main clutch K2 is closed, so that the motor output shaft 22 is directly connected to the central shaft 20 of the transmission and thus to the output shaft 25 of the transmission. In this first type of gear change, which is systematically shown in FIG. 8, the engine torque M _{M is transferred} from one of the two power transmission branches (in FIG. 8: 16 ) to the other power transmission branch (in FIG. 8: 18 ) . The two separating clutches K1, K2 are therefore overlap in the area between t _i and t _ii in such a way that the torques add up, so that the engine torque M _{M can be} transferred from one gear to the next gear without load interruption. This first type of gear change corresponds to that of a conventional double clutch transmission.

A second type of gear change is achieved in the drive trains 10 of FIGS. 1 to 7 in the following manner. In this regard, reference is made to FIG. 9.

In this second type of gear change (e.g. a gear change from first to second gear in FIG. 1a), the two gears involved are assigned to one of the two power transmission branches (here: 16 ). Thus, an interruption in traction must inevitably occur during a shift in the power transmission branch 16 concerned. In Fig. 1a, the first clutch K1 is closed both in the first gear and in the second gear. In order to avoid a drop in tractive force in the course of the shifting process from 1 to 2, the second main clutch K2 is closed - also overlapping in time - when the first gear is disengaged. Here, the torque on the shaft 22 is transmitted to the output shaft 25 . In FIG. 9, the main clutch K1 is opened and the main clutch K2 is closed in a time overlap in a range between t ₁ and t ₂ . Between t ₂ and t ₃ , the main clutch K2 alone transfers engine torque M _M to the output shaft 25 . In the period between t ₃ and t ₄ , the main clutch K2 is again opened and the main clutch K1 is closed, overlapping in time.

Due to the parallelism of the main clutches K1, K2 and the power transmission branches 16 , 18 , however, not only a pull-in force can be avoided during the switching operations; by suitable control of the two main clutches K1, K2 - and possibly the torque or the speed of the engine - in the drive trains shown, special synchronous units for the clutches can be dispensed with.

In the drive trains 10 , 10 a, it is so that the gear changes 4-5 and 5-6 are carried out according to the first type, all other gear changes on the second type. Therefore, all clutches can be designed as dog clutches KK1-KK4.

In the embodiments 10b and 10c, it is the case that they are somewhat shorter in comparison between the embodiments 10, 10a; however, in these drive trains the direct gear is the fourth gear and thus the only gear assigned to the second power transmission branch 18 . Therefore, only gear changes 3-4 and 4-5 can be carried out according to the first type and gear changes 1-2 , 2-3 according to the second type. However, gear change 5-6 must be interrupted. However, it has been shown that subjectively this is almost without disadvantage for the driver, since the absolute torque difference between the fifth and the sixth gear is relatively small.

On the other hand, the gear changes of the second type always take place with a traction force bridging by means of a torque that is higher than the torque in the highest gear, namely by means of one of the gears 3 - N-1.

In FIGS. 5 and 6 are two drive lines 10 d and 10 e ge shows, each having three shafts. The embodiment of FIG. 6 is particularly preferred, because with this, as can be seen in Table 6a, the gear changes 2-3 , 3-4 and 4-5 can be carried out according to the first type ( FIG. 8). Only the gear change 1-2 takes place according to the second type ( Fig. 9). The gear change 5-6 takes place, although here the torque is transferred from the power transmission branch 18 to the power transmission branch 16 , without bridging the tractive force, since the clutch SK3 must first be separated from the idler gear 64 e during this gear change and then be coupled to the idler gear 68 e . Da (to be assigned in the embodiments of FIGS. 5 and 6 are each two passages through a central fixed gear wheel which is coupled with the hollow shaft 24, the second power transmission branch 18 in Fig. 5, the gears 4 and 6, in Fig. 6, the gears 3 and 5 ), the respective idler gears ( 60 d, 68 d or 56 e, 64 e) must be separable from their respective countershafts 28 ; at least when the two countershafts 28 act on the same output shaft 25 .

The above statements refer to gear changes all on upshifts in train operations. It understands that with some gear changes also downshifts in the train operation under load are possible, as well as thrust and Thrust downshifts.

Claims (15)

1. Automable motor vehicle drive train ( 10 ), with

• - A step transmission ( 14 ) with a plurality N of gears ( 1-6 , R), which has a first and a second parallel power transmission branch ( 16 , 18 ),
• - A first and a second main clutch (K1, K2), which are assigned to the first and the second power transmission branch ( 16 , 18 ), and
• - Control means ( 15 ) which control the main clutches (K1, K2) and the step transmission ( 14 ) in a first type of gear change in such a way that the drive shaft ( 25 ) to be transmitted from a torque (M _ab ) under load from one of the two power transmission branches (e.g. 16 ) are completely transferred to the other power transmission branch (e.g. 18 ),

characterized in that
the second power transmission branch ( 18 ) one or more of the gears 2 to N-1 of the N-speed step transmission ( 14 ) are assigned, the control means ( 15 ) the main couplings (K1, K2) and the step transmission ( 14 ) control a second type of gear change such that the torque to be transmitted (M _ab ) is transferred from one gear of the first power transmission branch ( 16 ) to another gear of the first power transmission branch ( 16 ) and that for the period (t ₃ -t ₂ ) a traction force interruption in the first power transmission branch ( 16 ) the second power transmission branch ( 18 ) transmits a torque (M _M ) to the output shaft ( 25 ). 2. Drive train according to claim 1, characterized in that in a third type of gear change, the torque to be transmitted (M _ab ) from one gear ( 5 ) of the first power transmission branch ( 16 ) to another gear ( 6 ) of the same power transmission branch ( 16 ) is transferred and that for the period of an interruption of traction in the first power transmission branch ( 16 ) the other power transmission branch ( 18 ) transmits no torque to the output shaft ( 25 ). 3. Drive train according to claim 1 or 2, characterized in that the second power transmission branch ( 18 ) is assigned a single gear ( 5 ; 4 ). 4. Drive train according to claim 3, characterized in that the single gear of the N-1. Gear ( 5 ) is. 5. Drive train according to claim 3, characterized in that the single gear of the N-2nd Gear ( 4 ) is. 6. Drive train according to claims 1 or 2, characterized in that the second power transmission branch are assigned two gears ( 3 , 5 ). 7. Drive train according to claim 6, characterized in that one of the two gears ( 3 , 5 ) of the second power transmission branch ( 18 ) of the N-1st Gear of the N-speed stage gearbox is. 8. Drive train according to claim 6 or 7, characterized in that the two gears ( 3 , 5 ) of the second power transmission branch ( 18 ) do not follow one another. 9. Drive train according to one of claims 1-8, characterized in that the gear ( 4 ; 5 ) or the gears ( 3 , 5 ) of the second power transmission branch ( 18 ) are assigned to a wheel set which is adjacent to one of the main clutch lungs (K1, K2). 10. Drive train according to one of claims 1 to 9, characterized in that the step transmission ( 14 ) for engaging and disengaging at least one of the gears which have a higher gear ratio than the lowest, the second power transmission branch ( 18 ) associated gear ( 5th ; 4 ; 3 ), a non-synchronized positive clutch (KK). 11. Drive train according to one of claims 1 to 10, characterized characterized in that the two main clutches (K1, K2) be are arranged adjacent to each other. 12. A method for controlling a drive train ( 10 ) of a motor vehicle, the drive train ( 10 ) comprising:

• - A step transmission ( 14 ) with a plurality N of forward gears ( 1-6 , R), which comprises a first and a second parallel power transmission branch ( 16 , 18 ), and
• a first and a second main clutch (K1, K2) which are assigned to the first and the second power transmission branch ( 16 , 18 ),

the main clutches (K1, K2) and the step transmission ( 14 ) being controlled in a first type of gear change in such a way that the torque (M _ab ) to be transmitted to an output shaft ( 25 ) under load from one of the two power transmission _branches (e.g. 16 ) is completely transferred to the other power transmission branch (for example 18 ), characterized in that
the main clutches (K1, K2) and the step transmission ( 14 ) are also controlled in such a way in a second type of gear change that the torque to be transmitted (M _ab ) from one gear of the first power transmission branch ( 16 ) to another gear of the first power transmission branch ( 16 ) and that for the period (t ₃ -t ₂ ) of an interruption in traction in the first power transmission branch ( 16 ), the second power transmission branch ( 18 ) by means of one of the gears 2 to N-1, a torque (M _M ) on the Output shaft ( 25 ) transmits. 13. The method according to claim 12, characterized in that in a third type of gear change, the torque to be transmitted (M _ab ) from one gear ( 5 ) of the first power transmission branch ( 16 ) to another gear ( 6 ) of the same power transmission branch ( 16 ) is transferred and that for the period of a traction force interruption in the first power transmission branch ( 16 ) the other power transmission branch ( 18 ) transmits no torque to the output shaft ( 25 ). 14. The method according to claim 12 or 13, characterized in that in the second type of gear change ( 1-2 , 2-3 ) when shifting up during train operation, the first main clutch (K1) is opened, while at about the same time the second main clutch (K2) for torque takeover is closed, and that after the design of the previous gear of the first power transmission branch ( 16 ), the second main clutch (K2) remains closed and / or until the first power transmission branch ( 16 ), the synchro speed of the gear to be engaged is reached. 15. The method according to any one of claims 12 to 14, characterized in that in the second type of gear change ( 1-2 , 2-3 ) when shifting down, the first main clutch (K1) is initially opened, while approximately the second main clutch ( K2) is closed for torque takeover, and that after disengaging the previous gear of the first power transmission branch ( 16 ), the first main clutch is closed again and the second main clutch (K2) remains closed and / or until the first power transmission branch ( 16 ) the synchronous speed of the gear to be engaged has been reached.