Testing and calibrating device for an evaluation circuit for a linear oxygen probe (lambda probe)

• US 20030080003A1
• Filed: 11/22/2002
• Published: 05/01/2003
• Est. Priority Date: 05/24/2000
• Status: Active Grant

• Current Assignee: Continental Automotive GmbH (Continental AG)
• Original Assignee: Siemens AG
• Inventors: Bolz, Stephan, Akhavan, Dariusch
• Granted Patent: US 6,960,290 B2
• Time in Patent Office: Days
• US Class Current: 205/784.5
• CPC Class Codes: G01N 27/4175 Calibrating or checking the analyser

Abstract

A testing and calibrating device for an evaluation circuit of a linear oxygen probe (S) of an internal combustion engine is disclosed. Said device comprises a probe equivalent circuit (SES) having the same terminals (Vs+, Vs−/Vp−, Vp+ and Rc) as the oxygen probe (S). The probe equivalent circuit can largely emulate the electrical and chemical behaviors of the oxygen probe (S) and simulate probe faults and, at least during a testing and calibrating process, is connected to the evaluation circuit in place of the oxygen probe (S) or is connected parallel to said oxygen probe.

Claims

1. A testing and calibrating device for an evaluation circuit for a linear oxygen probe in an internal combustion engine, comprising:

a probe equivalent circuit having the same connections as the oxygen probe, which largely emulates the electrical and chemical behaviour of the oxygen probe and can simulate probe faults, and which is connected to the evaluation circuit instead of the oxygen probe, or in parallel with it, at least during a testing and calibrating process.

2. The device as claimed in claim 1, wherein the probe equivalent circuit comprises an inverting integrator with integral-proportional-integral response,

whose non-inverting input is connected to the connection and is connected to the connection via a series circuit comprising a resistor and a resistor,

whose inverting input is connected firstly via a resistor to the junction point between the two resistors and to the connection, and secondly via a resistor to a further connection,

whose output is connected to its inverting input via a capacitor which has a series circuit comprising a capacitor and a resistor connected in parallel with it, and

wherein the inverting integrator has an inverter connected downstream of it,

whose inverting input is connected to the output of the integrator via a resistor,

whose non-inverting input is connected to the connection, and

whose output is connected to its inverting input via a resistor and to the connection via a resistor.

3. The device as claimed in claim 2, wherein a switch is arranged between the output of the inverter and the resistors.

4. The device as claimed in claim 2, wherein selected potentials can be applied to the connection.

5. The device as claimed in claim 4, wherein selected potentials are applied to the connection via an external switch.

6. The device as claimed in claim 2, wherein a switch is arranged between the output of the integrator

and the capacitor, on the one hand, and the resistor on the other.

7. The device as claimed in claim 2, wherein a switch is arranged between the first probe connection and the second probe connection.

8. The device as claimed in claim 1, wherein an external computer is provided which controls the testing and calibration processes and checks the response of the evaluation circuit under the various operating conditions at the end of production of the evaluation circuit (automated test system).

9. The device as claimed in claim 1, wherein during operation of the oxygen probe, the probe equivalent circuit is connected in parallel with the oxygen probe at a probe temperature of below 200°

C. during the probe'"'"'s heating phase.

10. The device as claimed in claim 9, wherein the measurement accuracy is checked and age-related tolerance discrepancies in the evaluation circuit are equalised by using the probe equivalent circuit in the heating phase of the oxygen probe to set various operating points and by storing the evaluation circuit'"'"'s pump-current measured values Ip measured in the process for the purpose of further processing.

11. A method for operating a testing and calibrating device for an evaluation circuit for a linear oxygen probe in an internal combustion engine, comprising the steps of:

coupling a probe equivalent circuit having the same connections as the oxygen probe, which largely emulates the electrical and chemical behaviour of the oxygen probe and can simulate probe faults, with the evaluation circuit instead of the oxygen probe during a testing and calibrating process.

12. The device as claimed in claim 11, further comprising the step of applying selected potentials to the connection.

13. The method as claimed in claim 11, further comprising the step of applying selected potentials to the connection via an external switch.

14. The method as claimed in claim 11, wherein an external computer is provided which controls the testing and calibration processes and checks the response of the evaluation circuit under the various operating conditions at the end of production of the evaluation circuit.

15. The method as claimed in claim 11, wherein during operation of the oxygen probe, the probe equivalent circuit is connected in parallel with the oxygen probe at a probe temperature of below 200°

C. during the probe'"'"'s heating phase.

16. The method as claimed in claim 15, wherein the measurement accuracy is checked and age-related tolerance discrepancies in the evaluation circuit are equalised by using the probe equivalent circuit in the heating phase of the oxygen probe to set various operating points and by storing the evaluation circuit'"'"'s pump-current measured values Ip measured in the process for the purpose of further processing.

17. A method for operating a testing and calibrating device for an evaluation circuit for a linear oxygen probe in an internal combustion engine, comprising the steps of:

coupling a probe equivalent circuit having the same connections as the oxygen probe, which largely emulates the electrical and chemical behaviour of the oxygen probe and can simulate probe faults, with the evaluation circuit instead of the oxygen probe in parallel with the oxygen probe, at least during a testing and calibrating process.

18. The device as claimed in claim 17, further comprising the step of applying selected potentials to the connection.

19. The method as claimed in claim 17, wherein an external computer is provided which controls the testing and calibration processes and checks the response of the evaluation circuit under the various operating conditions at the end of production of the evaluation circuit.

20. The method as claimed in claim 17, wherein the measurement accuracy is checked and age-related tolerance discrepancies in the evaluation circuit are equalised by using the probe equivalent circuit in the heating phase of the oxygen probe to set various operating points and by storing the evaluation circuit'"'"'s pump-current measured values Ip measured in the process for the purpose of further processing.