Planar polarographic probe for determining the .lambda. value of gas mixtures
First Claim
1. Planar polarographic probe for determining the lambda value of gas mixtures, particularly of exhaust gases of internal combustion engines, having at least the following units:
- a pumping cell (A),a diffusion unit (B) with a diffusion resistance preceding a pumping electrode (6) of the pumping cell (A) anda heater unit (C),made of at least three solid electrolyte foils, namely,a first solid electrolyte foil (1) forming the pumping cell (A) and havingan outer and an inner pumping electrode (6),of which the inner pumping electrode is arrangedon the solid electrolyte foil (1)in a diffusion zone (10) for the gas being measured andconductive tracks for the pump electrodes;
a second solid electrolyte foil (9) having a diffusion zone and forming the diffusion unit (B); and
a third solid electrolyte foil (14) forming heater unit (C);
the diffusion zone (10) being defined exclusively by an aperture, formed near the inner pumping electrode, in the second solid electrolyte foil (9) laminated together with the first solid electrolyte foil (1) and the third solid electrolyte foil (14),anda porous sintered body (11) filling said aperture,made by the steps of sintering a ceramic foil to render the same porous, andembedding the resulting porous sintered body (11) in said aperture, thereby protecting said body against damage during any subsequent lamination step.
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Accused Products
Abstract
A planar polarographic probe for determining the λ value of gas mixtures, in particular of exhaust gases of internal combustion engines, having at least the following units: a pumping cell (A), a diffusion unit (B) with a diffusion resistance preceding a pumping electrode of the pumping cell (A) and, if necessary, a heating unit (C) is proposed in which the diffusion resistance of the diffusion unit (B) is formed by a preshaped body which becomes porous on sintering and which is inserted into the unsintered probe.
Such a polarographic probe enables a sensor to be constructed in a simple manner which is particularly suitable for production, with increased reproducibility of the diffusion resistance.
128 Citations
11 Claims
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1. Planar polarographic probe for determining the lambda value of gas mixtures, particularly of exhaust gases of internal combustion engines, having at least the following units:
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a pumping cell (A), a diffusion unit (B) with a diffusion resistance preceding a pumping electrode (6) of the pumping cell (A) and a heater unit (C), made of at least three solid electrolyte foils, namely, a first solid electrolyte foil (1) forming the pumping cell (A) and having an outer and an inner pumping electrode (6), of which the inner pumping electrode is arranged on the solid electrolyte foil (1) in a diffusion zone (10) for the gas being measured and conductive tracks for the pump electrodes; a second solid electrolyte foil (9) having a diffusion zone and forming the diffusion unit (B); and a third solid electrolyte foil (14) forming heater unit (C); the diffusion zone (10) being defined exclusively by an aperture, formed near the inner pumping electrode, in the second solid electrolyte foil (9) laminated together with the first solid electrolyte foil (1) and the third solid electrolyte foil (14), and a porous sintered body (11) filling said aperture, made by the steps of sintering a ceramic foil to render the same porous, and embedding the resulting porous sintered body (11) in said aperture, thereby protecting said body against damage during any subsequent lamination step. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. Planar polarographic probe for determining the lambda value of gas mixtures, particularly of exhaust gases of internal combustion engines, comprising
a pumping cell (A), a diffusion unit (B) with a diffusion resistance preceding a pumping electrode (6) of the pumping cell (A) and a heater unit (C), made of at least three solid electrolyte foils, namely, a first solid electrolyte foil(1) forming the pumping cell (A) and having an outer and an inner pumping electrode (6), of which the inner pumping electrode is arranged on the solid electrolyte foil (1) in a diffusion zone (10) for the gas being measured and conductive tracks for the pump electrodes; -
a second solid electrolyte foil (9) having a diffusion zone and forming the diffusion unit (B); and a third solid electrolyte foil (14) forming said heater unit (C); the diffusion zone (10) being defined exclusively by an aperture, formed near the inner pumping electrode, in the second solid electrolyte foil (9) laminated together with the first solid electrolyte foil (1) and the third solid electrolyte foil (14), into which aperture a porous sintered body (11), formed during a probe sintering process, is embedded; and further comprising a Nernst cell (N) having first and second electrodes, said first electrode being exposed to exhaust gas by being located adjacent the pumping electrode behind the preshaped bodies (11) which becomes porous on sintering and forms the diffusion resistance, said second electrode being exposed to a reference medium.
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Specification