Hydraulic control for a dual clutch transmission

1. A dual clutch transmission, comprising:

a first clutch which is actuated by a first hydraulic cylinder;

a second clutch which is actuated by a second hydraulic cylinder;

a plurality of shift devices for shifting gears, each of which are actuated by a hydraulically operated cylinder; and

a hydraulic energy source for supplying the first hydraulic cylinder, the second hydraulic cylinder and each hydraulically operated cylinder for the plurality of shifting devices with hydraulic energy,

wherein the hydraulic energy source has a first pump, a second pump and an electric drive driving only the second pump, and a line from the second pump is only connected to a line from the first pump, and

wherein a first check valve is arranged in the line directly downstream of the first pump and a second check valve is arranged in the line downstream of the second pump, directly before a connection of the line from the second pump and the line from the first pump.

2. The dual clutch transmission as claimed in claim 1 , wherein a safety valve block is provided, which, in a safety shifting position, cuts off the hydraulic energy source from the first hydraulic cylinder and the second hydraulic cylinder, such that the first hydraulic cylinder and the second hydraulic cylinder are unpressurized and shifts the first hydraulic cylinder and the second hydraulic cylinder, connecting the first hydraulic cylinder and the second hydraulic cylinder to a tank.

3. The dual clutch transmission as claimed in claim 1 , wherein the first hydraulic cylinder, the second hydraulic cylinder and a third hydraulic cylinder and the hydraulically operated cylinders have path sensors for detecting current cylinder position.

4. The dual clutch transmission as in claim 1 , wherein the plurality of shift devices is five shifting devices.

5. The dual clutch transmission as claimed in claim 1 , wherein the first pump is connected in parallel with the second pump.

6. The dual clutch transmission as claimed in claim 1 , wherein a cooling oil device is provided for cooling the first clutch and the second clutch.

7. The dual clutch transmission as claimed in claim 6 , wherein the cooling oil device has an oil cooler arranged downstream of the hydraulic energy source.

8. The dual clutch transmission as claimed in claim 7 , wherein, between the hydraulic energy source and the oil cooler, a branch is connected for diverting a cooling oil volume flow.

9. The dual clutch transmission as claimed in claim 7 , wherein the cooling oil device has a suction jet pump for increasing diverted cooling oil volume flow.

10. The dual clutch transmission as claimed in claim 9 , wherein the suction jet pump is arranged downstream of the oil cooler.

11. The dual clutch transmission as claimed in claim 1 , wherein a third clutch is actuated by a third hydraulic cylinder, and the hydraulic energy source supplies the third hydraulic cylinder with the hydraulic energy.

12. The dual clutch transmission as claimed in claim 11 , wherein a cooling oil device is provided for cooling the third clutch.

13. The dual clutch transmission as claimed in claim 1 , wherein, for hydraulic activation of the first hydraulic cylinder, a first pressure reduction unit is provided, for the hydraulic activation of the second hydraulic cylinder, a second pressure reduction unit is provided and for the hydraulic activation of the third hydraulic cylinder, a third pressure reduction unit is provided.

14. The dual clutch transmission as claimed in claim 13 , wherein, for the hydraulic activation, the first pressure reduction unit, the second pressure reduction unit and the third pressure reduction unit are each associated with a corresponding hydraulic control valve.

15. The dual clutch transmission as claimed in claim 13 , wherein, tor the hydraulic activation of the hydraulic cylinders, an on-off valve arrangement is provided.