Group transmission device

1. A group transmission device for a motor vehicle, comprising:

a main group ( 11 ) with a central synchronizing unit ( 12 ) assigned to several shifting units ( 13 , 14 , 15 ) for synchronizing at least two main group shifting units ( 13 , 14 , 15 ) for changing a main group transmission ratio,

at least one auxiliary group ( 16 ) with at least one auxiliary group shifting unit ( 17 ) for changing an auxiliary group transmission ratio, and a control unit ( 18 ) which is provided to actuate in a shifting operation the auxiliary group shifting unit ( 17 ) and the central synchronizing unit ( 12 ) in order to change an overall gear ratio,

the (open and/or closed-loop) control unit ( 18 ) being provided to actuate the auxiliary group shifting unit ( 17 ) the central synchronizing unit ( 12 ) in parallel at least intermittently, the central synchronizing unit ( 12 ) permitting a synchronizing action independent of an actuation of the shifting with units ( 13 , 14 , 15 ).

2. The group transmission device according to claim 1 , wherein the auxiliary group shifting unit ( 17 ) comprises a synchronizer and the control unit ( 18 ) is adapted to actuate the central synchronizing unit ( 12 ) of the main group ( 11 ) during a synchronization phase of the auxiliary group shifting unit ( 17 ).

3. The group transmission device according to claim 1 , wherein the control unit ( 18 ) is an open- and/or closed-loop unit provided to synchronize the auxiliary group shifting unit ( 17 ) at least partially by means of the central synchronizing unit ( 12 ).

4. The group transmission arrangement according to claim 1 , wherein the central synchronizing unit ( 12 ) comprises at least one active synchronizing actuator with a countershaft-mounted stator which is provided for changing a speed of a countershaft ( 19 ).

5. The group transmission device according to claim 1 , wherein the central synchronizing unit ( 12 ) is pressure-controlled and the control unit ( 18 ) is provided to apply an actuating pressure to the central synchronizing unit ( 12 ) in an actuation phase of the auxiliary group shifting unit ( 17 ).

6. The group transmission device according to claim 5 , wherein the auxiliary group shifting unit ( 17 ) is pressure-controlled and the control unit ( 18 ) is provided to apply an actuating pressure to the auxiliary group shifting unit ( 17 ) before the actuating pressure is applied to the central synchronizing unit ( 12 ).

7. The group transmission device according to claim 5 , wherein the control unit ( 18 ) is provided to apply the actuating pressure to the central synchronizing unit ( 12 ) in a synchronization phase of the auxiliary group shifting unit ( 17 ).

8. The group transmission device according to claim 5 , wherein the control unit ( 18 ) is provided to reduce the actuating pressure of the central synchronizing unit ( 12 ) essentially to zero during the actuation phase of the auxiliary group shifting unit ( 17 ).

9. The group transmission device according to claim 7 , wherein the control unit ( 18 ) is in at least one operating state provided to reduce the actuating pressure of the central synchronizing unit ( 12 ) essentially to zero before the synchronization phase of the auxiliary group shifting unit ( 17 ) is completed.

10. A method for operating a group transmission device of a motor vehicle, the group transmission device comprising at least one main group ( 11 ) with at least one central synchronizing unit ( 12 ) for synchronizing at least two main group shifting units ( 13 , 14 , 15 ) for changing a main group transmission ratio, and at least one auxiliary group ( 16 ) with at least one auxiliary group shifting unit ( 17 ) for changing an auxiliary group transmission ratio, the method comprising the step of actuating the auxiliary group shifting unit ( 17 ) and the central synchronizing unit ( 12 ) in parallel at least intermittently in a shifting operation for changing an overall gear ratio.