Seven-gear gearbox for a motorcar double clutch transmission

1. Seven-gear gearbox for a motorcar double clutch transmission, comprising:

a gear case;

a first inner input shaft ( 10 ) and a second outer input shaft ( 12 ) arranged coaxial to the first, said first and second input shafts ( 10 , 12 ) being supported on the gear case ( 52 );

first and second output shafts ( 14 , 16 );

a first group of driving gearwheels ( 21 , 23 , 27 ) carried by the first input shaft ( 10 ) so as to-be drivingly connected for rotation therewith, said first group of driving gearwheels being associated to a first gear (I), to a third gear (III), to a fifth gear (V) and to a seventh gear (VII);

a second group of driving gearwheels ( 22 , 24 ) carried by the second input shaft ( 12 ) so as to be drivingly connected for rotation therewith, said second group of driving gearwheels being associated to a second gear (II), to a fourth gear (IV), to a sixth gear (VI) and to a reverse gear (R);

a first group of driven gearwheels ( 32 , 35 , 36 , 37 ) idly mounted on the first output shaft ( 14 );

a second group of driven gearwheels ( 31 , 33 , 34 , 38 ) idly mounted on the second output shaft ( 16 ); and

a first end support ( 54 ), a second end support ( 56 ) and a third intermediate support ( 58 , 60 ) arranged to support the first and second input shafts ( 10 , 12 ) on the gear case ( 52 ), wherein the first end support comprises a bearing ( 54 ) fitted between the gear case ( 52 ) and an end portion of the first input shaft ( 10 ) opposite a first side of the gearbox, wherein the second end support comprises a bearing ( 56 ) fitted between the gear case ( 52 ) and a portion of the second input shaft ( 12 ) facing the first side of the gearbox, and wherein the third intermediate support comprises a first bearing ( 58 ) radially interposed between the first and second input shafts ( 10 , 12 ) and a second bearing ( 60 ) fitted between the second input shaft ( 12 ) and the gear case ( 52 ) so as to be axially aligned or superimposed with the first bearing ( 58 ).

2. The gearbox of claim 1 , wherein the third intermediate support ( 58 , 60 ) is placed essentially equally spaced from the first and second end supports ( 54 , 56 , 57 ).

3. The gearbox of claim 1 , wherein the first and second end supports comprise each a ball bearing ( 54 , 56 ) or a tapered roller bearing.

4. The gearbox of claim 1 , wherein the bearings ( 58 , 60 ) forming the third intermediate support are ball bearings or roller bearings.

5. The gearbox of claim 1 , further comprising a roller cage ( 57 ) radially interposed between the first and second input shafts ( 10 , 12 ) in axially aligned or superimposed arrangement relative to the bearing ( 56 ) of the second end support.

6. The gearbox of claim 1 , wherein the first and second output shafts ( 14 , 16 ) are supported on the gear case ( 52 ) each by means of a pair of end supports ( 64 , 66 , 70 , 72 ).

7. The gearbox of claim 6 , wherein the end supports ( 64 , 66 , 70 , 72 ) of the first and second output shafts ( 14 , 16 ) are axially aligned or superimposed each with a respective end support ( 54 , 56 ) of the first and second input shafts ( 10 , 12 ).

8. The gearbox of claim 6 , wherein the end supports ( 64 , 66 , 70 , 72 ) of the first and second output shafts ( 14 , 16 ) are tapered roller bearings.

9. The gearbox of claim 6 , wherein the first and second output shafts ( 14 , 16 ) are also supported on the gear case ( 52 ) by means of a third intermediate support ( 68 , 74 ).

10. The gearbox of claim 9 , wherein the third intermediate support ( 68 , 74 ) of the first and second output shafts ( 14 , 16 ) is axially aligned or superimposed with the third intermediate support of the first and second input shafts ( 10 , 12 ).

11. The gearbox of claim 1 , wherein

the first group of driving gearwheels includes a first driving gearwheel ( 21 ) associated to the first gear (I), a second driving gearwheel ( 23 ) associated both to the third gear (III) and to the fifth gear (V), and a third driving gearwheel ( 27 ) associated to the seventh gear (VII);

the second group of driving gearwheels includes a fourth driving gearwheel ( 22 ) associated both to the second gear (II) and to the reverse gear (R), and a fifth driving gearwheel ( 24 ) associated both to the fourth gear (IV) and to the sixth gear (VI);

the first group of driven gearwheels includes a first driven gearwheel ( 37 ) meshing with the third driving gearwheel ( 27 ) to realize the seventh gear (VII), a second driven gearwheel ( 35 ) meshing with the second driving gearwheel ( 23 ) to realize the fifth gear (V), a third driven gearwheel ( 36 ) meshing with the fifth driving gearwheel ( 24 ) to realize the sixth gear (VI), and a fourth driven gearwheel ( 32 ) meshing with the fourth driving gearwheel ( 22 ) to realize the second gear (II); and

the second group of driven gearwheels includes a fifth driven gearwheel ( 31 ) meshing with the first driving gearwheel ( 21 ) to realize the first gear (I), a sixth driven gearwheel ( 33 ) meshing with the second driving gearwheel ( 23 ) to realize the third gear (III), a seventh driven gearwheel ( 34 ) meshing with the fifth driving gearwheel ( 24 ) to realize the fourth gear (IV), and an eighth driven gearwheel ( 38 ) arranged to be driven to rotate by the fourth driving gearwheel ( 22 ) to realize the reverse gear (R).

12. The gearbox of claim 11 , wherein the eighth driven gearwheel ( 38 ) meshes with the fourth driven gearwheel ( 32 ) in such a manner that upon engagement 6 f the reverse gear (R) the driving torque is transmitted from the fourth driving gearwheel ( 22 ) to the fourth driven gearwheel ( 32 ) and from this one to the eighth driven gearwheel ( 38 ).

13. The gearbox of claim 11 , further comprising a lay shaft ( 84 ) on which are idly mounted first and second intermediate gearwheels of reverse gear ( 80 , 82 ), fast for rotation with each other, wherein the first intermediate gearwheel ( 80 ) permanently meshes with the fourth driving gearwheel ( 22 ) and the second intermediate gearwheel ( 82 ) permanently meshes with the eighth driven gearwheel ( 38 ).

14. The gearbox of claim 11 , further comprising an intermediate gearwheel of reverse gear ( 86 ) which is idly mounted on the first output shaft ( 14 ), is fast for rotation with the fourth driven gearwheel ( 32 ) and permanently meshes with the eighth driven gearwheel ( 38 ).

15. The gearbox according of claim 11 , further comprising:

a first coupling sleeve ( 44 ) of a synchroniser, arranged to couple selectively the first and second driven gearwheels ( 37 , 35 ) for rotation with the first output shaft ( 14 ) to engage the seventh gear (VII) or the fifth gear (V), respectively;

a second coupling sleeve ( 46 ) of a synchroniser, arranged to couple selectively the third and fourth driven gearwheels ( 36 , 32 ) for rotation with the first output shaft ( 14 ) to engage the sixth gear (VI) or the second gear (II), respectively;

a third coupling sleeve ( 48 ) of a synchroniser, arranged to couple selectively the fifth and sixth driven gearwheels ( 31 , 33 ) for rotation with the second output shaft ( 16 ) to engage the first gear (I) or the third gear (III), respectively; and

a fourth coupling sleeve ( 50 ) of a synchroniser, arranged to couple selectively the seventh and eighth driven gearwheels ( 34 , 38 ) for rotation with the second output shaft ( 16 ) to engage the fourth gear (IV) or the reverse gear (R), respectively.

16. The gearbox of claim 11 , wherein the first and third driving gearwheels ( 21 , 27 ) are arranged adjacently at an and of the first input shaft ( 10 ) opposite the first side of the gearbox.