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Planar polarographic probe for determining the .lambda. value of gas mixtures

  • US 5,169,512 A
  • Filed: 09/18/1990
  • Issued: 12/08/1992
  • Est. Priority Date: 04/08/1988
  • Status: Expired due to Fees
First Claim
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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:

  • 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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