Method and arrangement for detecting the oxygen content in a gas

• US 6,200,458 B1
• Filed: 12/31/1998
• Issued: 03/13/2001
• Est. Priority Date: 01/02/1998
• Status: Expired due to Term

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Brida, Peter, Graser, Theodor, Hoetzel, Gerhard
• Primary Examiner(s): Warden, Sr., Robert J.
• Assistant Examiner(s): Olsen, Kaj K.
• Application Number:
  US09/223,970
• Time in Patent Office: 803 Days
• Field of Search: 204/424, 204/425, 204/427, 204/426, 204/402, 204/400, 204/421, 204/406, 205/784.5, 205/775, 205/784
• US Class Current: 205/784
• CPC Class Codes: G01N 27/417 using cells , i.e. more than one cell and probes with solid electrolytes

Abstract

The invention is directed to a method for detecting the oxygen content in a gas to be measured. At least one concentration cell operating in accordance with the Nernst principle is provided. The concentration cell includes a measuring electrode communicating with the gas and a solid electrolyte and a reference electrode connected to the measuring electrode through the solid electrolyte. A pump-current pulse is applied between the reference electrode and the measuring electrode and, directly after the end of each pump-current pulse, the current flow between the reference electrode and the measuring electrode is reversed in a pulse-like manner.

Claims

1. A method for detecting the oxygen content in a gas to be measured, the method comprising the steps of:

providing at least one concentration cell operating in accordance with the Nernst principle to supply a signal indicative of said oxygen content in said gas with said concentration cell including;

a measuring electrode communicating with said gas;

a solid electrolyte; and

, a reference electrode connected to said measuring electrode through said solid electrolyte;

applying a periodic pump-current pulse between said reference electrode and said measuring electrode; and

,

directly after the end of each pump-current pulse, applying a counter-current pulse to said concentration cell to reverse the current flow between said reference electrode and said measuring electrode in a pulse-like manner whereby a depolarization of said concentration cell is obtained.

2. The method of claim 1, comprising the further step of applying a counter-current pulse of a pregiven duration and a pregiven current intensity between said reference electrode and said measuring electrode and said current pulse being in a direction opposite to said pump-current pulse.

3. The method of claim 2, comprising the further step of so selecting said duration and said current intensity that the charge generated by said counter-current pulse is markedly less than the charge generated by said pump-current pulse.

4. The method of claim 1, comprising establishing a short circuit of a pregiven duration between said reference electrode and said measuring electrode with said step of applying a counter-current pulse to reverse the current flow.

5. The method of claim 1, wherein said counter-current pulse is shorter than said pump-current pulse.

6. An arrangement for detecting the oxygen content in a gas to be measured, the arrangement comprising:

at least one concentration cell operating on the Nernst principle to supply a signal indicative of said oxygen content in said gas;

said concentration cell including;

a measuring electrode communicating with said gas;

a solid electrolyte; and

, a reference electrode connected to said measuring electrode through said solid electrolyte;

a pump-current source for supplying a periodic pump-current pulse;

first means for coupling in said pump-current pulse between said reference electrode and said measuring electrode;

at least one counter-current source for supplying a counter-current pulse of a pregiven duration and a pregiven current intensity; and

,

second means for coupling in said counter-current pulse between said reference electrode and said measuring electrode after said pump-current pulse in a direction opposite thereto to obtain a depolarization of said concentration cell.

7. The arrangement of claim 6, wherein said counter-current pulse is shorter than said pump-current pulse.

8. The arrangement of claim 7, wherein the duration of said counter-current pulse is approximately one-twentieth to one-tenth of the duration of said pump-current pulse.

9. The arrangement of claim 6, comprising the further step of adjusting said duration and said current intensity of said counter-current pulse so that the charge generated by said counter-current pulse is significantly less than the charge generated by said pump-current pulse.

10. An arrangement for detecting the oxygen content in a gas to be measured, the arrangement comprising:

at least one concentration cell operating on the Nernst principle to supply a signal indicative of said oxygen content in said gas;

said concentration cell including;

a measuring electrode communicating with said gas;

a solid electrolyte; and

, a reference electrode connected to said measuring electrode through said solid electrolyte;

a pump-current source for supplying a periodic pump-current pulse;

means for coupling in said pump-current pulse between said reference electrode and said measuring electrode; and

,

switching means for establishing a short circuit or a low ohmic connection between said reference electrode and said measuring electrode over a pregiven time span to obtain a depolarization of said concentration cell.

11. The arrangement of claim 10, wherein said short circuit corresponds to a short-circuit pulse shorter than said pump-current pulse.

12. The arrangement of claim 11, wherein the duration of said short-circuit pulse is approximately one-twentieth to one-tenth of the duration of said pump-current pulse.