Circuit configuration for controlling a pump current of an exhaust probe in a motor vehicle

A circuit configuration for controlling a pump current includes a microcontroller, an analog circuit and a read-only memory. A pulse-width modulated signal, which is output by the micro-controller, is converted, by using the analog circuit, into the pump current for a pump cell of an exhaust probe which operates according to the principle of the galvanic oxygen concentration cell with a solid electrolyte. A pump current actual value is determined from a voltage drop across a measuring resistor, and a pump current setpoint value is determined from a voltage difference between an actual value of a Nernst voltage in the corresponding measuring cell and a predefined setpoint value. An exhaust probe configuration is also provided.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagrammatic sectional view of a NO

x sensor;

FIG. 2 is a block circuit diagram of the circuit configuration according to the invention for controlling a pump current; and

FIG. 3 is a diagrammatic plan view of a NO

x probe.

1. In combination with an exhaust probe having a solid electrolyte, a pump cell and a measuring cell, and operating according to a principle of a galvanic oxygen concentration cell, a circuit configuration for controlling a pump current for the pump cell, comprising:

2. The circuit configuration according to claim 1, wherein said read-only memory is a programmable read-only memory.

3. The circuit configuration according to claim 1, wherein said read-only memory is integrated into said microcontroller.

4. The circuit configuration according to claim 1, including:

5. The circuit configuration according to claim 1, wherein:

6. The circuit configuration according to claim 5, wherein:

7. The circuit configuration according to claim 6, wherein:

8. The circuit configuration according to claim 5, wherein:

9. The circuit configuration according to claim 1, wherein:

10. The circuit configuration according to claim 1, including:

11. An exhaust probe configuration, comprising:

12. The exhaust probe configuration according to claim 11, wherein said read-only memory is a programmable read-only memory.

13. The exhaust probe configuration according to claim 11, wherein said read-only memory i s integrated into said microcontroller.

14. The exhaust probe configuration according to claim 11, including:

15. The exhaust probe configuration according to claim 11, wherein:

16. The exhaust probe configuration according to claim 15, wherein:

17. The exhaust probe configuration according to claim 16, wherein:

18. The exhaust probe configuration according to claim 15, wherein:

19. The exhaust probe configuration according to claim 11, wherein:

20. The exhaust probe configuration according to claim 11, including: