Measuring and testing – Gas analysis – Gas of combustion
Reexamination Certificate
1999-07-19
2001-08-21
Larkin, Daniel S. (Department: 2856)
Measuring and testing
Gas analysis
Gas of combustion
C073S023320, C073S031050, C422S090000, C422S094000, C204S426000
Reexamination Certificate
active
06276191
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an oxygen sensor for determining the oxygen concentration in the exhaust gas flow of an internal combustion engine, in which the sensor includes an outer electrode exposed to the exhaust side and a reference electrode exposed to a reference atmosphere or to the ambient air.
BACKGROUND INFORMATION
An oxygen sensor is described, by way of example, in U.S. Pat. No. 5,531,879. In an oxygen sensor of this type, used as a &lgr;-probe, there exists the problem that, when the oxygen sensor heats up, the sensor characteristic curve shifts due to humidity, penetrating exhaust, or residues in or on the housing or mounting parts on the reference side. This phenomenon, known as CSD behavior (Characteristic Shift Down), is treated in the oxygen sensor proposed in the above-referenced U.S. patent by employing for the reference electrode a metal, e.g., gold or a gold-platinum alloy, that is not catalytically active.
In other oxygen sensors of the related art, the CSD behavior is avoided either by the reference side being completely sealed off from the exhaust side, or by an active Pt or Pt/Pd electrode or component parts on the reference side being heated. All of the known measures in the related art for avoiding the CSD problem are either complicated or expensive.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an oxygen sensor that is suitable for use as a &lgr;-probe in a motor vehicle, in which the CSD problem is solved by a simple and cost-effective means.
The above object is achieved in accordance with a first preferred aspect of the present invention in that a space surrounding the reference electrode or a space adjacent to the reference electrode has an adsorbing agent and/or an absorbing agent. The adsorbing/absorbing agent that is used can be applied either in the form of a loose powder packing, in the form of pellets, as rings or as an intermediate layer in a packing or on other suitable mounting locations on the reference side.
An adsorbing/absorbing material of this type, given sufficient temperature stability, is able to take up and to bind H
2
O, CO, hydrocarbons, etc., penetrating on the reference side.
Zeolites are particularly suited as an adsorbing/absorbing material. Zeolites have proven to be particularly suited technically, in many respects, as adsorption/absorption agents based on their particularly large interior hollow spaces, which are accessible via pore openings that are of equal size.
The advantage of an oxygen sensor according to the present invention that is realized by the introduction of zeolite material is particularly to be found in the fact that the reference electrode can also be made of a catalytically active metal.
A second oxygen sensor realized in accordance with the present invention is characterized in that the reference electrode or the reference-side mounting parts have at least one material that supplies on the reference side additional oxygen for the combustion of exhaust that has penetrated or of residues from the manufacturing process.
Preferred examples of such materials are Mn-oxide, Ba-oxide, or Ce-oxide, which, e.g., can be employed as a solution, as pellets, or as paste components. The measure proposed in accordance with the second preferred aspect, to provide the reference electrode or reference-side mounting parts with at least one material that supplies on the reference side additional oxygen for the combustion of exhaust that has penetrated or residues from the manufacturing process, can be combined particularly usefully with the proposed introduction or building up of an absorber/adsorber material. Thus an oxygen sensor realized according to the present invention avoids CSD effects that are caused by the manufacturing process and/or the operation or design.
REFERENCES:
patent: 4911892 (1990-03-01), Grace et al.
patent: 5512882 (1996-04-01), Stetter et al.
patent: 5531879 (1996-07-01), Zanini-Fisher et al.
patent: 5635627 (1997-06-01), Bytyn
patent: 5635628 (1997-06-01), Fleischer et al.
patent: 5668301 (1997-09-01), Hunter
patent: 5698771 (1997-12-01), Shields et al.
patent: 5747669 (1998-05-01), Suzuki
patent: 5814281 (1998-09-01), Williams et al.
patent: 5824271 (1998-10-01), Frank et al.
patent: 5827415 (1998-10-01), Gür et al.
patent: 5969231 (1999-10-01), Qu et al.
patent: 5970780 (1999-10-01), Mori
patent: 29 35 196 (1981-03-01), None
Moser Thomas
Neumann Harald
Schneider Jens Stefan
Schumann Bernd
Stanglmeier Frank
Kenyon & Kenyon
Larkin Daniel S.
Robert & Bosch GmbH
Wiggins David J.
LandOfFree
Oxygen sensor does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Oxygen sensor, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Oxygen sensor will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2548990