Method of operating a hybrid drive system and hybrid drive system with two partial drives

1. A method of operating a hybrid drive system with a main driving machine ( 11 ) and a supplementary driving machine ( 12 ) for a motor vehicle, comprising:

a first gear changing partial drive ( 15 ) with an input shaft ( 17 ) and an output shaft ( 23 ) and a first group of gear changing pairs of gearwheels each having a gearwheel connected in a rotationally fast way to its shaft and a switching gearwheel which can be switchably coupled to its shaft and whose input shaft ( 17 ) can be coupled to the main driving machine ( 11 );

a second gear changing partial drive ( 16 ) with an input shaft ( 18 ) and an output shaft ( 24 ) and a second group of gear changing pairs of gearwheels each having a gearwheel connected in a rotationally fast way to its shaft and a switching gearwheel which can be switchably coupled to its shaft and whose input shaft ( 18 ) is connectable in respect of drive to the supplementary driving machine ( 12 );

wherein the two input shafts ( 17 , 18 ) can be connected to one another in a rotationally fast way via a coupling unit ( 29 ),

characterised in

that, during operation by means of the main driving machine ( 11 ) only there is effected a gear change between two gears adjoining one another in the gear changing sequence by changing the torque flow from one gear changing partial drive to the other gear changing partial drive.

2. A method according to claim 1 ,

characterised in

that during operation by means of the supplementary driving machine only there is effected a gear change between two gears adjoining one another in the gear changing sequence by changing the torque flow from one gear changing partial drive to the other gear changing partial drive.

3. A hybrid drive system with a main driving machine ( 11 ) and a supplementary driving machine ( 12 ) for a motor vehicle, comprising:

a first gear changing partial drive ( 15 ) with an input shaft ( 17 ) and an output shaft ( 23 ) and a first group of gear changing pairs of gearwheels each having a gearwheel connected in a rotationally fast way to its shaft and a switching gearwheel which can be switchably coupled to its shaft and whose input shaft ( 17 ) can be coupled to the main driving machine ( 11 );

a second gear changing partial drive ( 16 ) with an input shaft ( 18 ) and an output shaft ( 24 ) and a second group of gear changing pairs of gearwheels each having a gearwheel connected in a rotationally fast way to its shaft and a switching gearwheel which can be switchably coupled to its shaft and whose input shaft ( 18 ) is connectable in respect of drive to the supplementary driving machine ( 12 );

wherein the pairs of gear changing gearwheels, in the gear changing sequence, are alternately associated with one of the gear changing partial drives ( 15 , 16 ) and wherein the two input shafts ( 17 , 18 ) can be connected to one another in a rotationally fast way via a coupling unit ( 29 ).

4. A hybrid drive system according to claim 3 ,

characterised in

that the main driving machine ( 11 ) can be coupled via a friction coupling ( 14 ) to the first input shaft ( 17 ).

5. A hybrid drive system according to claim 3 ,

characterised in

that the supplementary driving machine ( 12 ) is coupled via a gearwheel ( 20 ) to a gearwheel ( 19 ) firmly arranged on the second input shaft ( 18 ), wherein the gearwheels ( 20 , 19 ) form a transmission stage.

6. A hybrid drive system according to claim 3 ,

characterised in

that an auxiliary driven machine ( 13 ) is coupled via a gearwheel ( 21 ) to a gearwheel ( 19 ) firmly arranged on the second input shaft ( 18 ), wherein the gearwheels ( 21 , 19 ) form a transmission stage.

7. A hybrid drive system according to claim 3 ,

characterised in

that the two input shafts ( 17 , 18 ) are arranged coaxially and can be coupled to one another via a coaxially arranged coupling unit ( 29 ).

8. A hybrid drive system according to claim 7 ,

characterised in

that the two output shafts ( 23 , 24 ) are integrally connected to one another.

9. A hybrid drive system according to claim 3 ,

characterised in

that the two input shafts ( 17 , 18 ) are arranged in parallel relative to one another and that the coupling unit ( 29 ) is arranged on one of the input shafts and acts on a switching gearwheel ( 50 ) which is arranged on said input shaft and which forms a pair of gearwheels with a gearwheel ( 45 ) firmly arranged on the other input shaft.

10. A hybrid drive system according to claim 9 ,

characterised in

that the two output shafts ( 23 , 24 ) are arranged in parallel relative to their input shaft ( 17 , 18 ) and are coupled via fixed gearwheels ( 22 1 , 22 2 ) to an individual output gearwheel ( 28 ).

11. A hybrid drive system according to claim 3 ,

characterised in

that the two input shafts ( 17 , 18 ) are arranged in parallel relative to one another and that the coupling unit ( 29 ) is arranged on one of the input shafts and acts on a switching gearwheel ( 50 ) which is arranged on said input shaft and which forms a gear train with a gearwheel ( 20 ) firmly arranged on the other input shaft, especially via an intermediate gearwheel ( 19 ) connected to the supplementary driving machine ( 12 ).

12. A hybrid drive system according to claim 11 ,

characterised in

that the two output shafts ( 23 , 24 ) form one integral shaft member.

13. A hybrid drive system according to claim 3 ,

characterised in

that the first gear changing partial drive ( 15 ) comprises at least a first gear and a third gear, and that the second gear changing partial drive ( 16 ) comprises at least a second gear and a fourth gear.

14. A hybrid drive system according to claim 13 ,

characterised in

that the first gear changing partial drive ( 15 ) comprises a fifth gear and a reverse gear and that the second gear changing partial drive ( 16 ) comprises a sixth gear.