Exhaust gas purification system for a motor vehicle having a reducing agent storage tank, and associated operating method

1. An exhaust gas purification system for a motor vehicle having a predetermined maintenance interval, comprising:

a reducing agent storage tank for storing a reducing agent intended for exhaust gas purification, wherein the reducing agent storage tank is configured to have a capacity that is at least equal to a level predetermined by an assumed reducing agent consumption during the maintenance interval, and

means for preventing a restarting of the vehicle after the vehicle has been switched off if the reducing agent storage tank is emptied.

2. The exhaust gas purification system of claim 1 , wherein the reducing agent storage tank has a closure apparatus which is openable for refilling purposes, the closure apparatus being configured to protect against being opened other than during a maintenance operation.

3. The exhaust gas purification system of claim 1 , wherein the reducing agent storage tank has a closure apparatus which is openable for refilling purposes, the closure apparatus being configured to protect against being opened other than by authorized persons.

4. The exhaust gas purification system of claim 1 , wherein the reducing agent storage tank has a closure apparatus which is openable for refilling purposes, the closure apparatus being configured to protect against being opened other than after the maintenance interval has elapsed.

5. The exhaust gas purification system of claim 1 , wherein said system is provided with components for level monitoring for the purpose of monitoring the quantity of reducing agent that is present in the reducing agent storage tank, so that a warning signal is sent when the quantity of reducing agent drops below a determined residual quantity.

6. The exhaust gas purification system of claim 5 , wherein said residual quantity is determined based on an assumed consumption rate and the remaining running time until the end of the maintenance interval.

7. The exhaust gas purification system of claim 5 , wherein said residual quantity is determined based on a measured consumption rate and the remaining running time until the end of the maintenance interval.

8. A method for maintaining a motor vehicle having an exhaust gas purification system and a reducing agent storage tank for storing a reducing agent intended for exhaust gas purification, comprising:

preventing a restarting of the vehicle after the vehicle has been switched off if the reducing agent storage tank is emptied;

unlocking a closure device for the reducing agent storage tank, wherein said closure device is configured to only be openable during a maintenance operation; and

filling the reducing agent storage tank.

9. The method of claim 8 , wherein the steps of unlocking a closure device for the reducing agent storage tank and refilling the reducing storage tank are conducted during a maintenance operation.

10. The method of claim 8 , wherein the steps of unlocking a closure device for the reducing agent storage tank and refilling the reducing storage tank are conducted after the end of the maintenance interval.

11. A method for operating a motor vehicle having an exhaust gas purification system and a reducing agent storage tank for storing a reducing agent intended for exhaust gas purification, comprising:

operating the motor vehicle;

switching the motor vehicle off;

preventing a restarting of the vehicle after the vehicle has been switched off if the reducing agent storage tank is emptied;

unlocking a closure device for the reducing agent storage tank, wherein said closure device is configured to only be openable during a maintenance operation; and

filling the reducing agent storage tank.

12. A method for operating a motor vehicle having an exhaust gas purification system and a reducing agent storage tank for storing a reducing agent intended for exhaust gas purification, comprising:

operating the motor vehicle;

determining the quantity of reducing agent in the reducing agent storage tank and sending a warning signal if this quantity drops below a predetermined minimum quantity; and

switching the motor vehicle off;

preventing a restarting of the vehicle after the vehicle has been switched off if the reducing agent storage tank is emptied; and

unlocking a closure device for the reducing agent storage tank, wherein said closure device is configured to only be openable during a maintenance operation.

13. The method of claim 12 , further comprising the steps of:

determining a consumption rate for the reducing agent,

determining a reducing agent consumption quantity which is to be expected by the end of the maintenance interval, and

sending a warning signal if the expected consumption quantity exceeds the quantity of reducing agent in the reducing agent storage tank.

14. The method of claim 12 , further comprising:

effecting intervention measures to reduce a consumption rate for the reducing agent after a predetermined motor vehicle running distance has been exceeded following a warning signal being sent.

15. The method of claim 13 , further comprising:

effecting intervention measures to reduce a consumption rate for the reducing agent after a predetermined motor vehicle running distance has been exceeded following a warning signal being sent.

16. The method of claim 12 , further comprising

restricting the driving speed of the motor vehicle or the rotational speed of the motor vehicle drive engine is restricted after a predetermined motor vehicle running distance has been exceeded following a warning signal being sent.

17. The method of claim 13 , further comprising

restricting the driving speed of the motor vehicle or the rotational speed of the motor vehicle drive engine is restricted after a predetermined motor vehicle running distance has been exceeded following a warning signal being sent.