DE19924501A1 - Switched transmission for automobile has single switched coupling and at least 2 partial drive trains respectively coupled to engine drive shaft via switched coupling and directly - Google Patents

Abstract

The switched transmission has a single switched coupling (22) and at least 2 partial drive trains (10,12) with individual couplings (SK1-SK4, 60-62,64-67), for connecting the engine drive shaft (16) to one or other partial drive train via the switched clutch, the other partial drive train coupled directly to the engine drive shaft. An Independent claim for a switching method for a switched transmission is also included.

Description

The invention relates to a power shift Multi-step change gearbox with a powershift clutch according to the preamble of claim 1.

A power shift stage change gear of this type is known from DE-C-196 31 983. It shows one Double clutch transmission with a synchronizer. The dual clutch transmission has two input shafts, alternatively via one of the two friction clutches Double clutch can be connected to a motor shaft. Here are the gears of the straight gears on the one hand and the gears of the odd gears on the other hand on different countershafts. Hereby becomes a quick and comfortable gear change between reached two adjacent courses. However, it is considered considered disadvantageous that when switching with Gait jumps, e.g. B. when switching from second gear to fourth gear, the traction is interrupted. A Interruption-free switching under load is thus only possible between two gears, in which the power flow not on the same transmission input shaft.

To avoid this disadvantage, EP-A-0 827 861 a method for switching a dual clutch transmission suggested which also involves switching between two Gears arranged on the same transmission input shaft are allowed without interruption of tractive power. For this, a Auxiliary gear, which is on a different wave than the two  Gears is arranged to generate a filling moment used, the transmission ratio is greater than that Gear ratios of the source passage and the Finish line. The expression "filling moment" means the Generation of an interruption in traction in the drive train preventive torque transmission by an alternative used gear during the switching process of the originally switched source passage and the new target gear to be switched on. A disadvantage of this State of the art is that by means of the auxiliary gear sufficient filling torque is always provided and also the shifting time for changing gears normally is significantly extended. The torque curve shows especially with upshifts under train in the lower Gears, at the transmission output during the switching process strong fluctuations, so that the overall comfort Gear jumps across a gear compared to direct circuits - such as in Automatic transmission - by far not achieved due to the principle can be. Longer switching times have an additional effect negative on the driving comfort of the vehicle in which such a transmission is used. These are in today's automated series production Manual transmissions, which are sequential without Traction bridging are switchable, by the customer or by Driver of the vehicle very badly criticized. In particular in downshifts under load - such as, for example occur when overtaking - the driver misses the Spontaneity of the switching process.

Other types are also mentioned in DE-C-196 31 983 described for gearboxes for motor vehicles. Manual transmission, which usually with single-cone Synchronizers based on the Borg-Warner system are equipped; Synchronizers with  Synchronizer rings for gears; Automatic transmission with Torque converter; Engine control concepts, in which a speed adjustment of the transmission shafts by appropriate regulation of the speed of the internal combustion engine is carried out.

All known embodiments have the disadvantage that they are very expensive and complicated to manufacture need heavy parts.

In EP-A-0 797 025 and in DE-C-33 09 869 Transmission, especially for agricultural machinery, described in which two input shaft gears with identical Wear number of teeth through which each gear double is available. This will change gear under load in any order possible. Each of the two Input shafts is via a separate powershift clutch alternatively in the form of a friction clutch with a motor shaft connectable. These gears have the disadvantage that the Number of components, especially in gearboxes with one Variety of courses, which is very large, especially in Automotive at unacceptable cost and Loss of efficiency and too high Gearbox weight leads. They also need gearboxes an enlarged installation space, what their use, especially in passenger cars, almost impossible.

The object of the invention is to solve a problem Spur gear change gear of the type mentioned above train that it is a simple structure and a small one Has weight and requires a small space, and also its gears in almost without interruption of traction can be switched in any order.  

A gearbox is to be created, which is in terms of manufacturing costs and costs on the "Add-on" principle of automated manual transmissions oriented.

This object is achieved according to the invention by the characterizing features of claim 1 solved.

Furthermore, this object is achieved by the characteristic features of the method claims solved.

The invention provides for several (at least two) Partial transmission only a single power shift clutch (under Switchable clutch) required. You can choose each with one of at least two sub-transmissions be connected (integrated) to either one or the other other of these sub-transmissions with a drive part to connect in terms of drive. Are preferably for at least two gearbox clutches are provided, via which each of these sub-transmissions with the drive side or alternatively the output side of the powershift clutch is drivably connectable.

Accordingly, it is an essential feature of the invention instead of one of the number of partial transmissions as before corresponding number of power shift clutches - for example in the form of a double clutch - only one to use only powershift clutch. According to the Invention it is possible to use conventional synchronizer rings - at least in individual gears - to forego Saving space and components and reducing inertia and reduce costs.

By means of the invention, each partial transmission can optionally be used the drive side or the output side of the  Powershift clutch alternatively "drive connected" become. The phrase used here "drive-wise connected "includes the possibilities of a direct Connection or an indirect connection via other Rotational elements, especially gears and Gear transmission stages.

According to a particular embodiment of the invention it is provided that at least one gear step exists twice is, so that with defined circuits a direct Gear change from a source gear to a target gear possible is, without the need for another gear in between must be switched to an interruption of the traction Avoid drive train. By the additional Arrangement of selected gear levels in two It is possible to arrange directly into a desired one To switch target gear without the traction by means of a Aid to have to bridge to a Avoid traction interruption. This will make a faster and more comfortable gear change similar to in the double clutch transmissions mentioned at the beginning reached. One way is to use both third and fourth gear double. Of course, other gears can double be carried out. So there is the possibility at Shifting across two gears, i. H. at Circuits with skipping one in between Ganges, without a drop in the transmissible torque directly to switch to the desired target gear. This is especially important when overtaking, where often Circuits, for example from the fifth to the third or occur from sixth to fourth gear. Here should the intermediate course, i.e. the fourth or the fifth gear to be skipped. It is of course conceivable also to make the gearbox so that only one or more  be carried out twice as two gears. Compared to the preferred embodiment described above embodiments are also possible in which less or more gears between two different gears load switching, d. H. without torque interruption, can be executed. According to another Embodiment of the invention provides that first a change from one gearbox to another Partial gearbox and then feasible again if a source walk and a desired finish walk are in the same Partial gearboxes.

According to a method according to the invention for switching the powershift stage change gear according to the invention it is provided that preferably the load-carrying Partial transmission, d. H. the partial transmission, which is the source gear contains, directly with the drive side and thus with the Motor shaft is connected, while the partial transmission, which to take the load, d. H. the partial transmission, which contains the target gear or the auxiliary gear with which as Starting clutch connected power shift clutch connected becomes. In certain situations it can be beneficial no change after the load has been taken over by the target gear between the output side of the powershift clutch and the Drive side of the power shift clutch, d. H. the motor shaft to be carried out, especially if after a Downshifting in train operation of the motor vehicle already Driver's request for another one Downshift exists (double downshift). This will achieved an even faster gear change can be.

According to one embodiment of the invention Clutches, which are used to switch the lowest Gear stage of the partial transmission are provided as  Synchronizing clutches designed, preferably as Friction clutches of the cone type, through which the speeds of two shafts to be coupled together for the Gear shifting process are adaptable to each other, in particular with downshifts in overrun mode.

According to another embodiment of the invention provided that at least some of the clutches Claw clutches are and that to synchronize the drive-side and output-side parts of these Claw clutches a central synchronizing device for all dog clutches are provided. This is one Cost reduction, weight reduction and one Reduction of the installation space possible. The Synchronizer can be a motor and / or other additional facility for active synchronization exhibit. For example, it is possible, as in DE-A- 42 36 515 described, the couplings of the lowest Gear stage of the individual sub-transmission with synchron form clutches so as to increase the speed in particular To be able to adjust downshifts in overrun mode. The for changing from one gearbox to the other Gearboxes and vice versa used clutches between these sub-transmissions and the powershift clutch on the one hand and the motor shaft on the other preferably also with a synchronization device be provided or such a synchronizer contain. This ensures that a change of Part gear can be carried out automatically without that the driver of the motor vehicle driving the transmission contains, notices something of this.

According to another preferred embodiment of the Invention are for switching the individual gears Partial transmission in the closing direction and / or in  Preselected switching element provided in the opening direction, biased in particular by spring elements Shifting elements through which the times for engagement and / or disengagement of the gears can be shortened considerably. This also allows the design of the actuator system be influenced favorably.

According to a particular embodiment of the invention an electronic control device is provided by which is the synchronization of at least one gear corresponding speed setting of the internal combustion engine is feasible or at least supportable.

Method according to the invention for operating the powershift stage change gear of the invention described in the claims, which by Reference is hereby incorporated into the description.

Advantage of the invention over the aforementioned DE-C-33 09 869 and the mentioned EP-A-0 827 861: only one only power shift clutch required; as start-up and Powershift clutch is preferably a dry clutch intended; technical effort, weight and costs as well required space is smaller; for circuits in A gear already in the gearbox becomes overrun used as an auxiliary gear to bridge the thrust, the gear ratio of the auxiliary gear is larger than the gear ratios of source gear and of Finish gear, which creates additional friction wheel stages, as in the DE-C-196 31 983 are not required. When using double gear steps result the other advantages: higher driving comfort, because especially in cross-gear shifts, i.e. H. when skipping a corridor, for example from fourth gear to second gear, also a change from  one sub-transmission take place on the other sub-transmission and thus directly without the use of an auxiliary gear can be switched; the switching times are extremely short; the driver of the vehicle has more driving pleasure since the Circuit has a greater spontaneity.

Other advantages: there will be only one Powershift clutch required; as a powershift clutch preferably a dry clutch is provided; it won't Clutch overlap control device needed but for example only a slip-controlled or speed-controlled power shift clutch. By waiving conventional synchronizer rings results in a compact Construction, weight reduction, and shorter Switching times due to lower inertia. By Use of frictional synchronizing clutches for is the lowest gear level of the individual sub-transmissions no other synchronization facility and none Engine synchronization necessary. When using Synchronous couplings for connecting the partial transmissions of the Powershift clutch and / or the motor shaft is the Gear change process for a driver of the vehicle is not noticeable. There are several options for that Switching method. All parts can be conventional Be gear parts.

The invention is described below with reference to the Drawings based on preferred embodiments as Examples described. Show in the drawings

Fig. 1 shows schematically a powershift change gear transmission according to the invention with two countershafts, a coaxial to a motor shaft and a driven shaft with the two lowest gear steps structurally combined, central synchronization,

Fig. 2 shows another embodiment of a power shift stage change transmission according to the invention with two coaxial input shafts, a counter shaft and with dualized gear stages, wherein a likewise provided synchronizer is not shown,

Fig. 3, the step variable transmission of Fig. 2 in the switching position for a starting in first gear,

Fig. 4, the step variable transmission of FIG. 2 after completion of starting operation in the first gear,

Fig. 5, the change gear transmission of FIG. 2 in the switching position for an upshift from first gear to second gear, wherein the first phase is shown in which the source gear is still engaged and the power-shift clutch torque incorporates by clutch slip operation,

FIG. 6 shows the step change transmission from FIG. 2 in the shift position for an upshift from first gear to second gear in the second phase, in which the powershift clutch and the target gear completely transmit the torque and thus the source gear, ie the first gear; disengaged without load,

Fig. 7 shows the step change transmission of Fig. 2 in the shift position for an upshift from first gear to second gear, the shifting process being ended by the target gear, ie the second gear, no longer via the powershift clutch, but directly with the motor shaft connected is,

Fig. 8 schematically shows a further embodiment of a power shift stage change transmission according to the invention.

In all embodiments of a power shift Step change gear according to the invention can Power shift clutch at the same time as a starting clutch for the concerned vehicle can be used. According to others Embodiment can of course also a additional starting clutch may be provided.

. The power shift variable-speed transmission according to Figure 1 includes a gear train 10 with a countershaft V1; a partial transmission 12 with a countershaft V2; a first input shaft 14 which is connected or connectable directly or via further rotation element to a motor shaft 16 of a vehicle drive motor 18 ; a second input shaft 20 which is connected or connectable to the motor shaft 16 directly via a powershift clutch 22 or via further rotary elements; and an output shaft 24 for driving vehicle wheels. The second input shaft 20 is a hollow shaft through which the first input shaft 14 extends axially. The side of the powershift clutch 22 connected or connectable to the motor shaft 16 is also referred to below as the “drive side”. The other side of the powershift clutch 22 connected or connectable to the second input shaft 20 is hereinafter referred to as the “output side” of the powershift clutch 22 . The powershift clutch 22 is a friction clutch, preferably a dry friction clutch. The powershift clutch 22 can be used as a vehicle starting clutch and as a synchronizing element for synchronizing during gear shifting operations and can be controlled for this purpose as a function of an electronic control device 28 . The control by the control device 28 can take place as a function of the wishes of a driver of the vehicle in question and / or as a function of other vehicle operating states.

The first sub-transmission 10 can alternatively be connected to the first input shaft 14 by a first clutch SK1 and to the second input shaft 20 by a second clutch SK2. The second sub-transmission 12 can alternatively be connected to the first input shaft 14 via a fourth clutch SK4 and to the second input shaft 20 via a third clutch SK3. Each of the two sub-transmissions 10 and 12 can thus be connected either to the driven side of the clutch 22 or to the drive side of the clutch 22 and thus directly to the motor shaft 16 .

This results in the possibility of using the powershift clutch 22 not only as a starting clutch, but also as a synchronizing element for speed synchronization in the partial transmissions 10 and 12 when changing gears. This also makes it possible for the clutches SK1, SK2, Sk3 and SK4 and also for further clutches described below, form-fitting clutches, for. B. claw clutches, instead of non-positive clutches, such as friction clutches. Furthermore, there is the advantage over the prior art that only a single powershift clutch 22 is required.

In the drawings, the switchable gears are 1st, 2nd, 3rd, 4th, 5th and 6th for six different forward gears and a reverse gear "R" on the gear trains of these gears specified.

In the embodiment of Fig. 1 of the first partial transmission 33, 34, 35 and 36 loosely rotatably (idler gears) and a gear are on the first countershaft 10 V1 gears 32, 37 arranged in a rotationally fixed. The countershaft V1 of the first sub-transmission 10 is drivably connected via the first clutch SK1 and the gear 33 and a gear 38 to the first input shaft 14 and / or via the second clutch SK2, the gear 32 and a gear 39 to the second input shaft 20 . The two shift clutches SK1 and SK2 can be closed at the same time if, by closing the powershift clutch 22, speed equality is achieved on both sides of the two shift clutches SK1 and SK2. In this operating state, the torque can also be transmitted from the second clutch SK2 to the first clutch SK1 and then the second clutch SK2 can be opened.

Gears 40 , 41 , 42 , 43 , 44 and 45 are loosely arranged on the countershaft V2 of the second partial transmission 12 (idler gears) and a gear 46 is arranged in a rotationally fixed manner. The shift clutches SK3 and SK4 are also arranged on this countershaft V2. The countershaft V2 can be connected in terms of drive via the fourth clutch SK4 and the gearwheels 41 and 38 to the first input shaft 14 and / or via the third clutch SK3 and the gearwheels 40 and 39 to the second input shaft 20 .

Gears 50 , 51 , 52 and 53 are rotatably fixed on the output shaft 24 and two further gears 55 and 56 can be rotated loosely (idler gears) and a synchronizing device 58 is arranged between the two loose gears 55 and 56 . Synchronizing devices for speed adjustment of two rotating elements are state of the art, so that the synchronizing device 58 need not be described in detail. The gear 50 of the output shaft 24 is engaged with the gears 34 and 42 , and the gear 53 of the output shaft 24 is engaged with the two gears 36 and 44 , so that the third gear and the fourth gear are duplicated.

For shifting the third, fourth and fifth gear in the first sub-transmission 10 , further clutches 60 , 61 and 62 are arranged on the countershaft V1 in order to alternatively connect the countershaft V1 to the gearwheels 36 , 34 or 35 .

For shifting the third, fourth and sixth gears as well as the reverse gear in the second partial transmission 12 , further clutch clutches 64 , 65 , 66 and 67 are arranged on its countershaft V2 in order to connect these countershafts V2 to the gearwheels 44 , 42 , 43 and 45 , respectively. No additional clutches are required to shift the first gear and the second gear. In first gear, the connection of the motor shaft 16 to the output shaft 24 takes place via the powershift clutch 22 , the two shift clutches SK1 and SK2 and the synchronizing device 58 . When shifting the second gear, the torque is transmitted from the motor shaft 16 to the output shaft 24 via the powershift clutch 22 , the two shift clutches SK3 and SK4 and the synchronizing device 58 .

All clutches SK1, SK2, SK3, SK4, 60 , 61 , 62 , 64 , 65 , 66 , 67 can be friction clutches, but are preferably form-locking clutches, e.g. B. claw clutches, since in all gears the synchronization or adjustment of the speeds of the rotating elements to be connected to each other can be effected by slip operation in the powershift clutch 22 and / or the synchronizing device 58 .

A detailed description of the mode of operation of the powershift stage change gear according to the invention will now be given with reference to FIG. 1.

In the neutral position of a gear selector element manually adjustable by a driver of a vehicle, which is known in the prior art and is not shown, the powershift clutch 22 serving as the starting clutch and the shifting clutches SK1 and SK4 of the two partial transmissions 10 and 12 are opened, so that both countershafts V1 and V2 are separated from the motor shaft 16 . The embodiment according to FIG. 1 enables two operating modes which can be alternatively selected manually by a driver, for example a summer operating mode for starting in first gear and a winter operating mode for starting in second gear. In the summer operating mode for starting in first gear, the clutch SK2, which connects the countershaft V1 of the first sub-transmission 10 to the output side of the powershift clutch 22 , ie the second input shaft 20 , can already be closed while the other clutch SK1 is open in the neutral position. For the winter operating mode for starting in second gear, the clutch SK3, which connects the output side, ie the second input shaft 20 , of the powershift clutch 22 with the countershaft V2 of the second partial transmission 12 , can already be closed in a corresponding manner in the neutral position, whereas the other one Clutch SK4 of this second sub-transmission 12 must be open.

In stationary driving, i.e. when driving the vehicle with an engaged gear without performing a gear change, both the powershift clutch 22 and those clutches that open the load-bearing countershaft (e.g. V1 when driving in first gear or V2 when driving in second gear) are open ) with the output side of the powershift clutch 22 and the non-load-bearing countershaft (V2 when driving in first gear or V1 when driving in second gear) with motor shaft 16 . The clutch SK1 or SK4, which connects the load-bearing countershaft V1 or V2 with the motor shaft 16 , is closed. The clutch SK2 or SK3, which connects the non-load-bearing countershaft with the output side 20 of the power shift clutch 22 , can either be open or closed, preferably a closed one, particularly when using dual gear stages (e.g. third gear and fourth gear) State of these clutches is proposed to shorten the switching times.

To describe the starting process, a starting process using the first gear is described below, which in the embodiment according to FIG. 1 is located on the countershaft V1 of the first partial transmission 10 :
With the help of the clutch SK2, the operative connection between the powershift clutch 22 serving as the starting clutch and the countershaft V1, on which the first gear is located.

• 1. The clutch of the starting gear, which is contained in FIG. 1 in the synchronizing device 58 , is brought into operative connection with the relevant idler gear 56 .
• 2. The powershift clutch is closed or closed until speed equality between the drive side (motor shaft 16 ) and the driven side (input shaft 20 ) of the powershift clutch 22 is approximately reached. A small speed difference is necessary to switch the clutch SK1, which is designed as a claw clutch, so that the claws can find their associated gaps in the clutch, so that there is a small frictional slip operation in the power shift clutch 22 .
• 3. With the help of the clutch SK1, the operative connection between the countershaft V1 and the motor shaft 16 is established on the drive side of the powershift clutch 22 . Subsequently, the power shift clutch 22 is controlled or fully opened. The originally closed SK2 clutch is now torque-free and is disengaged, ie opened.

Shifting processes between two gear stages are described below as examples, the source gear being on the countershaft V2 of the second sub-transmission 12 as in FIG. 1 and the target gear being arranged on the countershaft V1 of the first sub-transmission 10 . The elements V1, SK1, SK2 and V2, SK4, SK3 are used for this gear change. The description of reverse gear changes would look the same, only the elements or the names of the elements would have to be exchanged, so that the elements V2, SK4, SK3 and V1, SK1, SK2 are then used. The specified numbering of the individual steps should not say anything about the chronological sequence, but should only clarify a logical sequence. It is namely advantageous to carry out individual steps in parallel, if possible, in order to limit the total switching time to a minimum.

The "method A" described below presupposes that a change in the partial transmission 10 or 12 takes place simultaneously with each gear change.

If the source gear, for example the third or fourth gear in FIG. 1, and the desired target gear are in the same partial transmission, then a change in the partial transmission that is not noticeable to the driver takes place.

Switching operation

• 1. With the help of the clutch SK2, the operative connection between the powershift clutch 22 and the countershaft V1 of the first sub-transmission 10 , on which the target gear is located, is already established.
• 2. The clutch of the target gear ( 58 , 60 , 61 or 62 ) is brought into operative connection with the relevant idler gear ( 56 , 36 , 35 , 34 ).
• 3. The powershift clutch 22 is closed or closed until the target gear has taken over the full torque. The shaft on which the source duct is located is thus free of load.
• 4. The clutch of the source gear is disengaged after it is now load-free.
• 5. The speed of the motor 18 is adjusted by controlled or regulated actuation of the power shift clutch 22 .
• 6. With the help of the clutch SK1, the operative connection between the countershaft V1 and the motor shaft 16 is established. Then the clutch SK2 is opened.

To engage (close) the clutch SK1 and the clutch ( 58 , 60 , 61 , 62 ) for the target gear, a speed adjustment must first be made. This can be achieved, for example, with the aid of individual known synchronous clutches, as are used today in manual transmissions, or with the aid of at least one device for synchronizing several shifting elements. This device can be arranged on the respective countershaft V1 or V2 or centrally on the input shaft and / or the output shaft 24 and can have an operative connection to the two countershafts V1 and V2 in order to be able to generate any speed. Purely mechanical solutions for synchronization are possible, as are servo-energetically supported embodiments. A further alternative is the speed adjustment with the help of the drive motor 18 or another auxiliary motor. The power shift clutch 22 can also be used to support the speed adjustment of the rotary elements to be coupled. A synchronization in all operating states only with the aid of the power shift clutch 22 is not possible, however, because the required synchronous speed cannot be established in downshifts in overrun mode.

Some alternative options for shifting under different load conditions are described below, in which no additional central synchronizing unit or the motor 18 are required to synchronize the individual gear stages, and nevertheless claw clutches can be used as shifting clutches for shifting the gears. There is a change of the partial transmission 10 or 12 simultaneously with each gear change. The source gear is arranged on the countershaft V2 and the target process on the countershaft V1. Downshifts in train operation and upshifts in pushing operation place special demands on the powershift clutch 22 , since in slipping operation before engaging (closing) the dog clutch for the target gear the torque capacity of the powershift clutch must still be very large, otherwise the target gear suddenly when engaging (closing) the dog clutch transmits the torque, which would have a negative impact on the driving comfort of the vehicle in question.

The upshift in train mode (engine pulls) a) synchronization

• 1. With the help of the clutch SK2, the operative connection between the output side (input shaft 20 ) of the powershift clutch 22 and the countershaft V1 of the first partial transmission 10 , on which the target gear (3rd, 4th or 5th) is located, is already established .
• 2. The powershift clutch 22 is closed or closed closed.
• 3. As soon as the countershaft V1 has approximately reached the speed of the desired target gear, the powershift clutch 22 is opened again.

b) switching operation

• 1. The clutch ( 60 , 61 or 62 ) of the target gear (3rd, 4th or 5th) is brought into operative connection with the relevant idler gear ( 36 , 34 or 35 ).
• 2. The powershift clutch 22 is closed or closed until the target gear has taken over the full torque.
• 3. The clutch of the source gear is disengaged without load.
• 4. In train operation, the speed of the engine 18 is reduced by a further controlled or regulated closing of the power shift clutch 22 .
• 5. When the synchronous speed is approximately reached, the operative connection between the countershaft V1 and the motor shaft 16 is established with the aid of the clutch SK1. Then the clutch SK2 is opened.

Downshifting process in train operation and upshifting in Push operation a) synchronization

• 1. With the help of the clutch SK3, the operative connection between the powershift clutch 22 and the countershaft V2 of the second sub-transmission 12 , on which the source gear (2nd, 3rd, 4th or 6th) is located, is already established. Between the motor shaft 16 and the countershaft V1 of the one partial transmission 10 , a drive connection is or will be established with the aid of the clutch SK1.
• 2. The powershift clutch 22 is opened in a controlled or regulated manner. In traction mode, the rpm of the motor 18 increases, while in the overrun mode, the speed of the motor 18 in this case is reduced (at constant throttle position).

b) switching operation

• 1. When the motor 18 and thus the countershaft V1 of the one partial transmission 10 approximately reaches the speed of the desired target gear, then the clutch ( 58 , 60 , 61 and 62 ) of the target gear (1st, 3rd, 4th or 5th Gear) in drive connection (operative connection) with the corresponding idler gear ( 56 , 36 , 34 or 35 ).
• 2. The powershift clutch 22 is opened or closed until the target gear (1st, 3rd, 4th or 5th gear) on the countershaft V1 of the partial transmission 10 transmits the full torque.
• 3. The clutch ( 64 , 65 or 66 ) of the source gear (2nd, 3rd, 4th or 6th gear) is disengaged without load.

A load change between the partial transmissions 10 and 12 is described below. A load change from the countershaft V2 to the countershaft V1 with the same gear ratio is described as an example. For a reverse change, only the names of the elements V1, SK1, SK2 and V2, SK4, SK3 have to be exchanged in V2, SK4, SK3 and V1, SK1, SK2.

• 1. With the help of the clutch SK2, the operative connection between the powershift clutch 22 and the non-load-bearing countershaft V1 of the one sub-transmission 10 is already established.
• 2. The powershift clutch 22 is controlled or regulated closed up to the sliding limit.
• 3. When the countershaft V2 of the other sub-transmission 12 approximately reaches the speed of the desired target gear, the powershift clutch 22 is opened again.
• 4. The clutch of the gear to be engaged is in Active connection brought with the idler gear concerned.
• 5. The powershift clutch 22 is closed or closed until the target gear has taken over the full torque.
• 6. The clutch of the source gear becomes load-free disengaged.

Different possibility

• 1. With the help of the clutch SK3, the operative connection between the closed power shift clutch 22 and the load-bearing countershaft V2 is established. The SK4 clutch is then opened. In order to engage the shift clutches, which are preferably designed as dog clutches, a brief sliding movement of the power shift clutch 22 may be necessary.
• 2. The clutch SK1 is brought into operative connection with the countershaft V1, ie the countershaft V1 and the motor shaft 16 are connected directly to one another. The SK2 clutch may have been opened beforehand.
• 3. The powershift clutch 22 serving as a starting clutch is controlled or regulated opened up to the sliding limit.
• 4. The clutch of the new gear or target gear is now at a small speed difference between their Indented input side and its output side.
• 5. The powershift clutch 22 is opened or closed until the countershaft V1 transmits the full torque.
• 6. The clutch of the source gear becomes load-free disengaged.

In the switching operations described so far, only the powershift clutch 22 was used for synchronization. Additional tools for speed adjustment of the speeds on the drive side and the output side of the clutch, such as synchronizer rings, central synchronization units or interventions in the engine management to adjust the engine speed are not absolutely necessary. In downshifts in overrun mode, the powershift clutch 22 alone is no longer sufficient for speed adjustment. In such operating conditions, other or additional elements are necessary. As already mentioned, a possible advantageous embodiment of the powershift transmission is to provide the clutches of the lowest gear stage of the partial transmissions 10 and 12 with synchronous clutches or friction clutches. These can additionally or exclusively be used to generate any required speed.

This means that the steps for Synchronization is just one of many options represent and no claim to exclusivity have. The following is an example of the Downshifting operation described in overrun mode, whereby Speed adjustment synchronizer clutches can be used.

Downshift in overrun a) synchronization

• 1. With the help of the clutch SK2, the operative connection between the powershift clutch 22 (on its output side) and the countershaft V1, on which the target gear is located, is already established.
• 2. The synchronous clutch ( 58 ) of the first gear is controlled or closed closed.
• 3. If the countershaft V1 the speed of the desired Has almost reached the finish line Synchronous clutch opened again.

b) switching operation

• 1. The clutch of the target gear is with the brought into active connection concerned idler gear.
• 2. The powershift clutch 22 is closed or closed until the target gear has taken over the full torque.
• 3. The clutch of the source gear becomes load-free disengaged.
• 4. In overrun mode, the speed of the motor 18 is increased by a further controlled or regulated closing of the powershift clutch 22 .
• 5. When the synchronous speed is approximately reached, the operative connection between the countershaft V1 and the motor shaft 16 is established with the aid of the clutch SK1. Then the clutch SK2 is opened.

In the following, a "method B" is described with the requirement that the source gear and the target gear lie in the same sub-transmission 10 or 12 .

For the implementation of the invention, it is of course not absolutely necessary to use double gears (gears), since gear shifts can also be carried out under load, ie with traction force bridging, without duplicating gears. If the source gear and target gear are not in the same sub-transmission 10 or 12 , the gear change can be carried out in one of the aforementioned ways. If, on the other hand, the source gear and the target gear are in the same sub-transmission 10 or 12 , then one of the gears can be used as an auxiliary gear for bridging the tractive force, which is arranged in the other sub-transmission in question, and its transmission ratio for gear shift operations smaller, but at Switching in overrun is larger than that of the source gear and the target gear.

All of the possible variations mentioned in EP-A-0 827 861 and in the other prior art documents are also possible with the present invention, with the decisive advantage that no double clutch, but only a single powershift clutch 22 is required.

The following shift processes between two gear stages or gears are described as examples, the source gear and the target gear being located on the countershaft V2 of the second sub-transmission 12 , as shown in FIG. 1, and a gear on the countershaft V1 of the one sub-transmission 10 being used as an auxiliary gear becomes. For the description of a reverse arrangement of the gears, only the designations V1, SK1, SK2 and V2, SK4, SK3 have to be exchanged in V2, SK4, SK3 and V1, SK1, SK2.

In the following exemplary switching operations, synchronization in gear shift operations takes place exclusively with the aid of the powershift clutch 22 ; in gear shift operations, the synchronizing clutch 58 of the lowest gear stage of the sub-transmission 10 or 12 concerned is used.

The following is an upshift in train operation described.

a) synchronization

• 1. With the help of the clutch SK2, the operative connection between the powershift clutch 22 and the countershaft V1, on which the auxiliary gear is located, is already established.
• 2. The powershift clutch 22 is closed or closed closed.
• 3. When the countershaft V1 has approximately reached the speed of the desired auxiliary gear, the powershift clutch 22 is opened again.

b) switching operation

• 1. The clutch of the auxiliary gear is in Active connection brought with the relevant idler gear.
• 2. The powershift clutch 22 is controlled or closed until it has taken over the full torque. The shaft on which the source duct is located is thus free of load.
• 3. The source passage is now disengaged.
• 4. By further closing the powershift clutch 22 in slip mode, the engine speed of the engine 18 is reduced, but the vehicle containing the multi-step transmission only accelerates imperceptibly due to its much higher inertia. The powershift clutch 22 is controlled or closed until the synchronous speed for the target process is approximately reached.
• 5. The clutch of the target gear is in Active connection brought with the relevant idler gear.
• 6. The powershift clutch 22 is opened or closed until the target gear directly connected to the engine 18 transmits the full torque.
• 7. The auxiliary gear is now disengaged without load.

The following is a downshift in train mode described.

a) synchronization

• 1. With the help of the clutch SK2, the operative connection between the powershift clutch 22 and the countershaft V1 of the one sub-transmission 10 is already established, on which the auxiliary gear is located.
• 2. The powershift clutch 22 is closed or closed closed.
• 3. When the countershaft V1 has approximately reached the speed of the auxiliary gear, the powershift clutch 22 is opened again.

b) switching operation

• 1. The clutch of the auxiliary gear is in Active connection brought with the corresponding idler gear.
• 2. The powershift clutch 22 is controlled or closed until it has taken over the full torque. The shaft on which the source duct is located is thus load-free.
• 3. The source corridor is disengaged without load.
• 4. By opening the powershift clutch 22 , the speed of the drive motor 18 is increased. The powershift clutch 22 is opened or closed until the synchronous speed for the target gear is approximately reached.
• 5. The clutch of the target gear is in Active connection brought with the corresponding idler gear.
• 6. The powershift clutch 22 is opened or closed until the target gear directly connected to the engine 18 transmits the full torque.
• 7. The finish gear is now disengaged.

The power flow to the traction drive motor 18 occurs in overrun mode. This means that in order to disengage the source gear without load, the torque acting on the transmission output 24 must be bridged by an auxiliary gear, the gear ratio of which must be greater than the gear ratio of the source gear and the target gear.

The following is an upshift in overrun described.

a) synchronization

• 1. With the help of the clutch SK2, the operative connection between the powershift clutch 22 and the countershaft V1 of the one sub-transmission 10 is already established, on which the auxiliary gear is located.
• 2. The synchronizer clutch of the synchronizer 58 for the first gear is closed or closed.
• 3. When the countershaft V1 has approximately reached the speed of the desired auxiliary gear, the synchronizer clutch of the synchronizing device 58 is opened again.

b) switching operation

• 1. The clutch of the auxiliary gear is in Active connection brought with the relevant idler gear.
• 2. The powershift clutch 22 is controlled or closed until it has taken over the full torque. The shaft on which the source duct is located is thus load-free.
• 3. The source corridor is now released without load.
• 4. By opening the powershift clutch 22 , the speed of the drive motor 18 is reduced. The powershift clutch 22 is controlled or regulated until the synchronous speed for the target gear is approximately reached.
• 5. The clutch of the target gear is in Active connection brought with the relevant idler gear.
• 6. The powershift clutch 22 is opened or closed until the target gear directly connected to the drive motor 18 transmits the full torque.
• 7. The auxiliary gear is now disengaged without load.

The following is a downshift in overrun described.

a) synchronization

• 1. With the help of the shift clutch SK2, the operative connection between the powershift clutch 22 and the countershaft V1 of the one partial transmission 10 is already established, on which the gear used in the alternative is located.
• 2. The synchronizer clutch of the synchronizer 58 for the first gear is closed or closed.
• 3. If the countershaft V1 the speed of the has almost reached the desired auxiliary course the synchronizer clutch opened again.

b) switching operation

• 1. The clutch of the auxiliary gear is in Active connection brought with the relevant idler gear.
• 2. The powershift clutch 22 is controlled or closed until it has taken over the full torque. The shaft on which the source duct is located is thus load-free.
• 3. The source corridor is now released without load.
• 4. By further closing the power shift clutch 22 , the speed of the drive motor 18 is increased. In this case, the powershift clutch 22 is controlled or regulated until the synchronous speed for the target gear is approximately reached.
• 5. The clutch of the target gear is in Active connection brought with the corresponding idler gear.
• 6. The powershift clutch 22 is opened or closed until the target gear directly connected to the drive motor 18 transmits the full torque.
• 7. The auxiliary gear is now disengaged without load.

To bridge the tractive force, a gear is generally required, the translation of which in the power flow direction translates more into "fast" than the translation of the source gear and the translation of the target gear. This means that a gear with a reduction in gear ratio is required in traction mode, while a gear with a higher gear ratio is required in overrun mode. This results in two special cases:

• 1. Downshift from the highest gear in train operation;
• 2. Upshift from first gear in overrun mode.

When shifting using an auxiliary gear, but should be done without duplicate gears, then gear steps are required for this  Gear ratio is less than that of the highest Ganges or larger than that of the smallest aisle. Out auxiliary devices are known from the prior art which work either positively or frictionally.

However, it is also possible to modify the transmission structure and the shifting method so that these additional auxiliary devices are only partially or not required at all. In a preferred embodiment of the transmission according to the invention, therefore, the highest gear and the second gear are arranged on one countershaft (countershaft V2 of the other sub-transmission 12 ), all further forward gears on the other countershaft (countershaft V1 of the one sub-transmission 10 ).

In downshifts from the highest gear, the source gear and the target gear are usually on different shafts (V1 and V2), with the exception of downshifts to second gear. This switching option is not available if the tensile force is to be bridged during the switching process. The shift strategy could provide for a change to a gear with a ratio between the second gear and the highest gear. Another option would be to interrupt the drive train as in a conventional automated step change transmission. For this purpose, the load-carrying path is connected to the output side of the powershift clutch 22 , the powershift clutch is opened or closed, the source gear is disengaged in the no-load state, the speed is adjusted with the aid of a synchronization device and / or engine synchronization, the target gear is engaged, the powershift clutch 22 is controlled or regulated closed and, if necessary, the load-carrying path is positively connected to the motor shaft 16 (for example with the aid of a claw coupling). In the case of upshifts from first gear, the shift strategy can provide that only one shift directly into second gear is permitted here. However, since only a small load acts on a desired shift from first gear to third gear, ie in a gear shift, in overrun mode, an interruption of the drive train is also easily possible here.

The circuit methods described above apply in a corresponding manner to the other embodiments of the invention, which are shown in FIGS. 2 to 8.

Furthermore, in all embodiments of the invention

• a) via the clutch SK1, the motor shaft 16 without the power shift clutch with the one partial transmission 10 ,
• b) via the clutch SK2, the output side of the powershift clutch 22 with this one partial transmission 10 ,
• c) via the clutch SK3, the output side of the powershift clutch 22 with the other sub-transmission 12 ,
• d) via the clutch SK4, the motor shaft 16 without the power shift clutch 22 with this other sub-transmission 12

each connectable in terms of drive. "Drive-like" means either connectable directly or via others Rotational elements, especially gears, clutches or Synchronizers connectable.

In all embodiments, they are functional, not necessarily constructive to each other corresponding parts with the same reference numbers.

The embodiment according to FIGS. 2 to 7 contains a powershift clutch 22 , preferably in the form of a friction clutch, the drive side of which is drivingly connected to a motor shaft 16 of a vehicle drive motor 18 and a first input shaft 14 . The output side of the powershift clutch 22 is connected to a second input shaft 20 , which is a hollow shaft through which the first input shaft 14 extends axially. The first input shaft 14 also extends through a hollow shaft V1 of a partial transmission 10 . This hollow shaft is referred to as countershaft V1 for easier comparison with FIG. 1.

The hollow countershaft V1 of the one sub-transmission 10 can be connected to the first input shaft 14 by a clutch SK1 and via this to the input side of the powershift clutch 22 and thus to the motor shaft 18 . Furthermore, this hollow countershaft V1 can be connected to the second input shaft 20 by a further clutch SK2 and by this to the output side of the powershift clutch 22 .

A further countershaft V2 of a further sub-transmission 12, which is arranged parallel to the above-mentioned shafts, can be connected by the clutch SK2 via a gear train to the gears 102 , 103 and 104 and the second input shaft 20 to the output side of the powershift clutch 22 . Furthermore, this countershaft V2 of the partial transmission 12 can be connected to the first input shaft 14 and thus to the motor shaft 18 by means of a clutch SK4 and a gear chain with the gear wheels 106 , 107 and 108 .

The reverse gear is labeled "R" and the six Forward gears are with 1st, 2nd, 3rd, 4th, 5th and 6th designated. The third gear and the fourth gear are available twice.

On the hollow countershaft V1, a gear 110 for the first gear is non-rotatably, another gear 112 for the third gear is non-rotatably and another gear 114 for the fifth gear is also non-rotatably arranged. Through the two clutches 116 and 118 , the countershaft V1 can be connected or disconnected either to the gear 112 of the third gear or the gear 114 of the fifth gear.

The gear 104 , which can be coupled to the second input shaft 20 by the clutch SK3, is arranged on this input shaft 20 so as to be freely rotatable.

The gear 102 for the fourth gear and a gear 120 for the second gear are each non-rotatably fastened on the countershaft V2 of the partial transmission 12 . Furthermore, gear 106 and gear 122 for third gear, 124 for sixth gear and 126 for reverse gear are each freely rotatable on countershaft V2. The gear 122 for the third gear can be connected to the countershaft V2 by means of a clutch 130 . The countershaft V2 can also alternatively be coupled to or separated from the gear 124 of the sixth gear or the gear 126 of the reverse gear R via one of the two clutches 132 , 133 . By means of the clutch SK4, the countershaft V2 can optionally be coupled to the gear 106 , which is freely rotatable on the countershaft V2.

On an output shaft 24 are gear 103 which meshes with gears 102 and 104 , gear 107 which meshes with gears 106 and 108 and gear 134 which meshes with second gear gear 120 is freely rotatable. Furthermore, a gear 136 , which is in engagement with the gear 124 , and a gear 138 , which is in engagement with the gear 114 , are each rotatably arranged on the output shaft 24 . A gearwheel 140 arranged on the output shaft 24 in a rotationally fixed manner engages with the two gearwheels 112 and 122 of the two third gears.

The output shaft 24 can be coupled or uncoupled by a clutch 142 with the gear 134 , by a further clutch 144 with the gear 103 , by a clutch 146 with the gear 107 or by a clutch 148 with a gear 150 , which is on the output shaft 124 is freely rotatable and is in engagement with the gear 110 of the first gear.

All clutches can be friction clutches, but are preferably positive clutches, for example dog clutches. All shift clutches, the power shift clutch 22 and the travel drive motor 18 are controlled or regulated by the electronic control device 28 .

FIGS. 3 to 7 show the power shift variable-speed transmission of FIG. 2 in different switching states.

In FIG. 3, the power flow between the motor shaft 16 and the output shaft 24 flows in the first gear through the powershift clutch 22 and the clutch 148 .

In FIG. 4, the power flow between the motor shaft 16 and the output shaft 24 does not flow through the powershift clutch 22 , but directly from the motor shaft 16 via the clutch 148 to the output shaft 24 .

FIG. 5 shows the change between the first gear and the second gear. Starting from FIG. 4, the clutch SK3 is closed in FIG. 5 and thus the output side of the powershift clutch 22 via the second input shaft 20 and the gear wheels 104 , 103 and 102 , the countershaft V2, the gears 120 and 134 drivingly connected. Thereafter, the rotational speed of the gear 134 is adapted to the rotational speed of the output shaft 24 by the slip operation of the powershift clutch 22 . When approximately synchronous operation is achieved, clutch 142 is closed.

Now the clutch SK1 can be opened. This results in the shift state of FIG. 6. Here, the torque between the motor shaft 16 and the output shaft 24 is transmitted via the powershift clutch 22 for the second gear. The drive side and the output side of the powershift clutch 22 have the same rotational speeds because they are closed. As a result, the SK4 clutch can now be closed and the SK3 clutch can then be opened. Thus, the switching state is transmitted in which for the second gear, the driving torque is not more than the power-shift clutch 22, but directly from the motor shaft 16 via the clutch SK4 and the clutch 142 to the output shaft 24 as shown in FIG. 7.

In an analogous manner to that described here for gears 1 and 2, the other gears can also be shifted using the powershift clutch 22 as a synchronizing clutch, and after the synchronization process, the torque transmission from the drive shaft 16 to the first input shaft 14 bypassing the powershift clutch 22 respectively. The operating methods described for the embodiment of FIG. 1 also apply analogously to the powershift stage change gear according to FIGS. 2 to 7.

The powershift stage change gear of FIGS. 2 to 7 requires a particularly small number of gears and is therefore a compact, relatively small structural unit which can be used, for example, for front-wheel drive vehicles and can be arranged transversely in the motor vehicle. The advantage is achieved, inter alia, that the gear chains 108 , 107 , 106 and 104 , 103 , 102 have such a gear ratio that they not only serve to connect the partial transmissions 10 and 12 , but also form gear ratios, namely gear ratios 3 and 4th

According to the basic idea of the transmission of FIGS. 2 and 7, it contains: A powershift step change transmission, comprising at least one input shaft ( 14 ; 20 ), at least one partial transmission ( 12 , V2, 24), at least one gear chain ( 108 , 107 ; 106 ; 104 , 103 , 102 ) between the at least one input shaft ( 14 ; 20 ) and the at least one partial transmission, at least one clutch arrangement (146; SK3, 144), the transmission ratio of the gear chain ( 108 , 107 , 106 ; 104 , 103 , 102 ) is selected such that the gear chain forms a gear (4.) which can be engaged or disengaged by opening the at least one clutch arrangement ( 146 ; SK3, 144 ).

According to a special embodiment of the transmission of FIGS. 2 to 7, power shiftable multi-step transmission is characterized in that two input shafts ( 14 ; 20 ) are provided, each of which has a gear chain ( 108 , 107 , 106 ; 104 , 103 , 102 ) , the translation of which is selected such that it forms a gear (4.K _M , 4.K _K ) which can be engaged by engaging a clutch arrangement ( 146 ; SK3, 144 ) or disengaged by opening.

According to the particular embodiment shown in FIGS. 2 to 7, it is provided that one input shaft ( 14 ) extends through the other input shaft ( 20 ), which is designed as a hollow shaft, that a countershaft hollow shaft (V1) is provided, which is arranged axially to the hollow input shaft ( 20 ) and through which the one input shaft ( 14 ) also extends, that the countershaft hollow shaft (V1) through a clutch arrangement (SK1, SK2) with one and / or other of the two input shafts ( 14 ; 20 ) can be coupled that at least one countershaft gear chain ( 112 , 140 , 122 ) is provided between the countershaft hollow shaft (V1) and the at least one partial transmission ( 12 , V2, 24 ).

Further, FIGS. 2 is provided according to 7, wherein the translation of the countershaft gears chain (112, 140, 122) is chosen such that it (3) forms a transmission gear, which by closing of at least one clutch arrangement (116, 130 ) can be engaged or disengaged by opening.

In the embodiment of a powershift stage change transmission according to the invention shown in FIG. 8, parts already described have corresponding parts provided with the same reference numbers. It contains a powershift clutch 22 , preferably in the form of a friction clutch, the drive side of which is connected or connectable to the motor shaft 16 of a vehicle drive motor 18 and a first transmission input shaft 14 , and the driven side of which is connected or connectable in a rotationally fixed manner to a second hollow transmission input shaft 20 . A countershaft V1 of a partial transmission 10 can be connected to the first input shaft 14 and thus to the motor shaft 16 via a clutch SK1 and a gear train 201 , without the power shift clutch 22 . Furthermore, this countershaft V1 can be connected via a clutch SK2 and a gear train 202 to the hollow input shaft 20 and thus to the output side of the powershift clutch 22 . As a result, the countershaft V1 can optionally be connected to the drive side and / or the output side of the powershift clutch 22 via the two clutch clutches SK1 and SK2. The countershaft V1 is provided with a synchronizing device 204 for synchronizing the drive sides and output sides of the two clutch clutches SK1 and SK2, in the event that one wishes to avoid an annoying increase in engine speed (decelerating) when shifting down from higher to lower gears.

A transmission shaft 212 of a further sub-transmission 12 can be connected via a clutch SK3, a transmission path 213 with a countershaft V2 and the hollow transmission input shaft 20 to the output side of the powershift clutch 22 and alternatively via a further clutch SK4 with the first transmission input shaft 14 and thus connectable to the motor drive shaft 16 on the drive side of the power shift clutch 22 . The transmission shaft 212 of the second partial transmission 12 is provided with a synchronizing device 214 and can be connected directly to the output shaft 24 via a further clutch 216 .

The countershaft V1 of the one sub-transmission 10 is connected via gears 218 and 219 to a hollow shaft 220 through which the transmission shaft 212 of the other sub-transmission 12 extends. Gearwheels 222 , 223 , 224 and 225, which are connected in a rotationally fixed manner to the hollow shaft 220, mesh with gearwheels 226 , 227 , 228 and 229 , respectively, which are freely rotatable on a gear shaft 230 and each with a clutch 231 , 232 , 233 or 234 are connectable. This gear shaft 230 can also be connected via couplings 235 and 236 to gear wheels 240 and 241 , respectively, which mesh with gear wheels 242 and 243 , which are connected in a rotationally fixed manner to one gear shaft 212 . The gear shaft 230 is connected in a rotationally fixed manner to the output shaft 24 via gear wheels 246 and 248 . A reverse gear "R" can thus be shifted and the six gears 1st, 2nd, 3rd, 4th, 5th or 6th can be shifted under load without interrupting the flow of force between the motor shaft 16 and the output shaft 24 .

The shafts 16 , 14 , 212 and 24 are arranged axially one behind the other. The shafts V1, V2 and 230 are arranged in parallel.

By using the powershift clutch 22 as a synchronizing clutch and by using the synchronizing devices 204 and 214 , all the switching clutches can be designed as form-fitting clutches, preferably as dog clutches.

The shift clutches and the power shift clutch 22 and the vehicle drive motor are controlled by the electronic control device 28 .

The operating methods described with reference to FIG. 1 for shifting the powershiftable step change transmission also apply analogously to the powershiftable step change transmission of FIG. 8, with the countershaft V2 being replaced by the transmission shaft 212 in the description.

Claims (16)

1. Power shiftable multi-step transmission with a power shift clutch ( 22 ) and with at least two partial transmissions ( 10 , 12 ), with shift clutches (SK1, SK2, SK3, SK4; 60 , 61 , 62 , 64 , 65 , 66 , 67 ; 116 , 118 , 130 , 132 , 142 , 144 , 146 , 148 ; 216 , 231 , 232 , 233 , 234 , 235 , 236 ) are provided, characterized in that the powershift clutch ( 22 ) by switchable elements (SK1, SK2, SK3, SK4 ) alternatively into a drive connection between a drive part ( 16 ) and one of the sub-transmissions ( 10 , 12 ) or into a drive connection between the drive part ( 16 ) another of the sub-transmissions ( 10 , 12 ) and can thereby be alternately assigned to one of the sub-transmissions can, and that the partial transmission or the partial transmission, to which the power shift clutch ( 22 ) is not assigned at the present time, connected or ver with a drive connection, which does not include a power shift clutch, to the drive part ( 16 ) is or are binding. 2. Powershift step change transmission according to claim 1, characterized in that the partial transmissions ( 10 , 12 ) each via a clutch (SK1, SK4) with the drive side of the powershift clutch ( 22 ) and via another clutch (SK2, SK3) with the output side of the Powershift clutch can be connected in terms of drive. 3. powershift step change transmission according to claim 1 or 2, characterized in that on at least one of the clutches a synchronous operation between the rotating elements to be coupled by them by frictional operation of the powershift clutch ( 22 ) is adjustable. 4. powershift stage change transmission according to one of the preceding claims, characterized in that in at least two of the clutches the torque from one clutch (SK2, SK3) to the other clutch (SK1, SK4) is transferable and for this purpose the rotating elements of the other clutch to be coupled (SK1, SK4) can be brought into synchronous operation by frictional engagement of the powershift clutch ( 22 ). 5. Power shiftable multi-step transmission according to one of the previous claims, characterized, that at least one gear is double, so that a direct at defined circuits Changing gear from a source gear to a target gear is possible without, in between, alternatively in one another gear must be switched. 6. powershift stage change transmission according to one of the preceding claims, characterized in that first a change of the torque transmission from one sub-transmission ( 10 , 12 ) to another sub-transmission ( 10 , 12 ) and then back to the one sub-transmission can be carried out when a source gear and a desired target gear are in the same sub-transmission. 7. Power shiftable multi-speed transmission according to one of the preceding claims, characterized in that clutches ( 58 ; 142 , 148 ; 231 , 235 ), which are provided for switching the lowest gear stage of the partial transmission ( 10 , 12 ), are designed as synchronizing clutches which the speeds of two rotary elements to be coupled together can be matched to one another for the gear shifting process, in particular in downshifts in overrun mode. 8. powershift stage change transmission according to one of the preceding claims, characterized in that at least some of the clutches are dog clutches and that for synchronizing the drive-side and output-side parts of these dog clutches each have at least one central synchronizing device ( 22 ; 58 ; 142 , 148 ; 204 , 214 ; 231 , 235 ) is provided for several of these dog clutches. 9. A method for shifting a powershift stage change transmission according to one of claims 1 to 8, wherein source gear and target gear are arranged in different sub-transmissions ( 10 , 12 ) and in the initial state the one, load-carrying sub-transmission with a motor shaft ( 16 ) bypassing a powershift clutch ( 22 ) is connectable and another part gearbox ( 12 , 10 ) to be switched into the power flow can be connected to the output side of the powershift clutch ( 22 ), characterized in that the powershift clutch ( 22 ) is closed or closed until the desired target gear is fully Has taken over moment; the clutch of the source gear is then disengaged without load; and then by controlled or regulated actuation of the power shift clutch ( 22 ) the speed of the vehicle drive motor ( 18 ) is adjusted. 10. The method for switching a powershift stage change gearbox according to one of claims 1 to 8, wherein the source gear and the target gear are arranged in different sub-transmissions ( 10 , 12 ) and in the initial state the one, load-carrying sub-transmission can be connected to the output side of the powershift clutch ( 22 ) and another sub-transmission to be switched into the power flow can be connected directly to the motor shaft bypassing the powershift clutch, characterized in that the clutch of the target gear is brought into operative connection with the idler gear in question; by a controlled or regulated actuation of the power shift clutch ( 22 ), the torque is now completely transmitted from the target gear; the clutch of the source gear is then disengaged without load. 11. A method for shifting a powershift stage change transmission according to one of claims 1 to 8, wherein source gear and target gear are arranged in the same sub-transmission ( 10 , 12 ) and in the initial state the one, load-carrying sub-transmission ( 10 , 12 ) bypassing the powershift clutch ( 22 ) can be connected to the motor shaft ( 16 ) and another partial transmission ( 12 , 10 ) to be switched into the power flow can be connected to the output side of the powershift clutch ( 22 ), characterized in that an auxiliary gear arranged in said other partial transmission for generating a filling torque is used, whose gear ratio in the power flow direction is smaller than the gear ratio of source gear and target gear; the powershift clutch ( 22 ) is closed or closed until the auxiliary gear has completely taken over the torque; the clutch of the source gear is then disengaged without load; the speed of the travel drive motor ( 18 ) is adjusted by a controlled or regulated actuation of the power shift clutch ( 22 ); the clutch of the target gear is brought into operative connection with the corresponding idler gear; The torque is now completely transmitted from the target gear by a controlled or regulated actuation of the powershift clutch and the auxiliary gear is thus disengaged without load. 12. The method for shifting a powershift stage change transmission according to one of claims 1 to 8, wherein the source gear and the target gear are arranged in the same sub-transmission ( 10 , 12 ) and in the initial state the one, load-carrying sub-transmission can be connected to the output side of the powershift clutch ( 22 ) and another sub-transmission to be switched into the power flow can be connected directly to the motor shaft ( 16 ), characterized in that an auxiliary gear arranged in the other sub-transmission mentioned at the beginning is used to generate a filling torque, the transmission ratio of which in the power flow direction is smaller than the transmission ratio of Source gear and target gear; the powershift clutch ( 22 ) is opened or closed until the speed of the travel drive motor ( 18 ) is adapted to engage this auxiliary gear; the clutch of the auxiliary gear is brought into operative connection with the idler gear concerned; the torque is now completely transmitted from the auxiliary gear by a controlled or regulated actuation of the power shift clutch; the clutch of the source gear is thus disengaged without load; the clutch of the target gear is brought into operative connection with the idler gear in question; The torque is now completely transmitted from the target gear by a controlled or regulated actuation of the power shift clutch. 13. Power shiftable step change transmission, comprising at least one input shaft ( 14 ; 20 ), at least one partial transmission ( 12 , V2, 24 ), at least one gear chain ( 108 , 107 , 106 ; 104 , 103 , 102 ) between the at least one input shaft ( 14 ; 20 ) and the at least one partial transmission, at least one clutch arrangement ( 146 ; SK3, 144 ), the translation of the gear chain ( 108 , 107 , 106 ; 104 , 103 , 102 ) being selected such that the gear chain has a gear (4th) forms, which can be engaged or disengaged by opening the at least one coupling arrangement ( 146 ; SK3, 144 ). 14. powershift stage change gear according to claim 13, characterized in that two input shafts ( 14 ; 20 ) are provided, each of which has a gear chain ( 108 , 107 , 106 ; 104 , 103 , 102 ), the translation of which is selected such that it forms a gear (4.K _M , 4.K _K ) which can be engaged or disengaged by opening a clutch arrangement ( 146 ; SK3, 144 ). 15. powershift stage change gear according to claim 14, characterized in that the one input shaft ( 14 ) extends through the other input shaft ( 20 ), which is designed as a hollow shaft, that a countershaft hollow shaft (V1) is provided, which is axially to the hollow input shaft ( 20 ) is arranged and through which an input shaft ( 14 ) also extends, that the countershaft hollow shaft (V1) can be coupled to one and / or other of the two input shafts ( 14 ; 20 ) by a coupling arrangement (SK1, SK2) is that at least one countershaft gear chain ( 112 , 140 , 122 ) is provided between the countershaft hollow shaft (V1) and the at least one partial transmission ( 12 , V2, 24 ). 16. powershift stage change gear according to claim 15, characterized in that the translation of the countershaft gear chain ( 112 , 140 , 122 ) is selected such that it forms a gear (3rd) which by closing at least one clutch arrangement ( 116 , 130 ) can be engaged or disengaged by opening.