Abstract: A gas sensor is described for detecting a physical property of a measuring gas, including detecting the oxygen concentration in the measuring gas. The gas sensor includes a sensor element having a diffusion barrier, which is arranged between a first solid electrolyte layer and a second solid electrolyte layer. The diffusion barrier has a necked-down portion, i.e., a concave profile, between the first and the second solid electrolyte layer. Accordingly, a first area, which the diffusion barrier occupies in a plane which lies between the side of the first solid electrolyte layer (facing the diffusion barrier) and the side of the second solid electrolyte layer (facing the diffusion barrier), is smaller than a second area on which the diffusion barrier covers the first or the second solid electrolyte.

Abstract: A sensor element for a sensor for determining the concentration of a gas component in a gas mixture, in particular the oxygen concentration in the exhaust gas of internal combustion engines, has two electrodes which, together with a solid electrolyte, form a pump cell, and one of these electrodes is exposed to the gas mixture via a porous protective layer. The sensor element also has a reference electrode which is situated on the solid electrolyte and is exposed to a reference gas. One of the two electrodes, with a reference electrode and the solid electrolyte, forms a concentration cell or a Nernst cell. To make the measured values produced by the sensor element insensitive to pressure fluctuations in the gas mixture, the electrode surface of the second electrode facing away from the solid electrolyte is coated with a finely porous diffusion layer, which is directly exposed to the gas mixture, and the second electrode is used as the reference electrode of the Nernst cell.

Abstract: For achieving a highest possible measuring accuracy of a circuit for measuring the internal resistance of an exhaust-gas sensor, a method and a circuit for measuring the internal resistance R1 (10) of an electrochemical cell (12) are provided for determining the temperature of an exhaust-gas sensor, especially of a motor vehicle. The circuit is provided with the objective to improve the control to a constant temperature to therefore also improve the performance of the exhaust-gas sensor. A measurement current I_Mess (20) is applied to the internal resistance R1 (10) of the electrochemical cell (12) and a resulting first voltage is detected. A switchover to a reference resistor R2 takes place from time to time or at regular time intervals. With a switchover to the reference resistor R2, the resulting second voltage is stored and thereafter is applied as a reference value for the measurement of the internal resistance R1 (10).

Abstract: A method is presented for determining the fuel/air ratio in the individual cylinders (single cylinder lambda) of an internal combustion engine having a plurality of cylinders, whose exhaust gases mix together in a common exhaust gas pipe system, from the signal of an exhaust gas probe, whose mounting location lies in the common exhaust gas pipe system, with the aid of an invertible model for the intermixing of the exhaust gases at the mounting location of the exhaust gas probe. The method is distinguished in that, in the determination of the single cylinder lambda from the signal of the one exhaust gas probe evaluated with the aid of the inverted model, the rotational angle position of the exhaust gas probe at its mounting position is taken into consideration.

Abstract: A probe is described for determining an oxygen concentration in a gas mixture, in particular in the exhaust gas of internal combustion engines, having a Nernst measuring cell, which has a first electrode (Nernst electrode) which is exposed to the gas mixture to be measured via a diffusion barrier, a second electrode (reference electrode) which is exposed to a reference gas, and a solid electrolyte body arranged between the first and the second electrode, and having a pump cell, which has a first electrode (inner pump electrode) which is exposed to the gas mixture via the diffusion barrier, a second electrode (outer pump electrode) which is exposed to the gas mixture, and a solid electrolyte body arranged between the first and the second electrode. The Nernst electrode and the inner pump electrode are connected at least in some sections via a joint supply conductor to a circuit arrangement for controlling and evaluating the probe.

Abstract: A lambda sensor for motor vehicles which permanently displays an at least temporary thermal overload by means of an indicator which, for fast reliable and unambiguous diagnosis without major additional measurement effort or expense, includes an indication material having at least one limit temperature adapted to the maximum allowable operating temperature of the component, and when this limit temperature is exceeded in at least one material component, a microstructural change ensues.

Abstract: A gas sensor is described for detecting a physical property of a measuring gas, including detecting the oxygen concentration in the measuring gas. The gas sensor includes a sensor element having a diffusion barrier, which is arranged between a first solid electrolyte layer and a second solid electrolyte layer. The diffusion barrier has a necked-down portion, i.e., a concave profile, between the first and the second solid electrolyte layer. Accordingly, a first area, which the diffusion barrier occupies in a plane which lies between the side of the first solid electrolyte layer (facing the diffusion barrier) and the side of the second solid electrolyte layer (facing the diffusion barrier), is smaller than a second area on which the diffusion barrier covers the first or the second solid electrolyte.

Abstract: A gas sensor has improved electrical properties. In the top view of the layer planes of the body of the sensor, printed circuit traces for electrodes are arranged outside of cavities in the body, e.g., outside of the reference air duct. Furthermore, the electrodes are enlarged in the direction of the exhaust-side end of the sensor. Also, the printed circuit traces have an increased layer thickness or are formed as a double layer.

Abstract: For achieving a highest possible measuring accuracy of a circuit for measuring the internal resistance of an exhaust-gas sensor, a method and a circuit for measuring the internal resistance R1 (10) of an electrochemical cell (12) are provided for determining the temperature of an exhaust-gas sensor, especially of a motor vehicle. The circuit is provided with the objective to improve the control to a constant temperature to therefore also improve the performance of the exhaust-gas sensor. A measurement current I_Mess (20) is applied to the internal resistance R1 (10) of the electrochemical cell (12) and a resulting first voltage is detected. A switchover to a reference resistor R2 takes place from time to time or at regular time intervals. With a switchover to the reference resistor R2, the resulting second voltage is stored and thereafter is applied as a reference value for the measurement of the internal resistance R1 (10).

Abstract: A method is presented for determining the fuel/air ratio in the individual cylinders (single cylinder lambda) of an internal combustion engine having a plurality of cylinders, whose exhaust gases mix together in a common exhaust gas pipe system, from the signal of an exhaust gas probe, whose mounting location lies in the common exhaust gas pipe system, with the aid of an invertible model for the intermixing of the exhaust gases at the mounting location of the exhaust gas probe. The method is distinguished in that, in the determination of the single cylinder lambda from the signal of the one exhaust gas probe evaluated with the aid of the inverted model, the rotational angle position of the exhaust gas probe at its mounting position is taken into consideration.

Abstract: The invention describes a sensor element for determining the concentration of gas components in gas mixtures, in particular in exhaust gases of combustion engines, comprising at least one measured gas space (13) and at least one gas inlet opening (17) through which the gas mixture is conveyable to the measured gas space (13), and at least one diffusion barrier (12) arranged between the gas inlet opening (17) and measured gas space (13). The diffusion barrier (12) has at least one region (14, 14a, 16) that contains a catalytically active material for establishing equilibrium in the gas mixture, and is divided into a coarse-pore and a fine-pore portion.

Abstract: The invention describes a sensor element for determining the concentration of gas components in gas mixtures, in particular in exhaust gases of combustion engines. It includes at least one measured gas space (13) and at least one gas inlet opening (17) through which the gas mixture is conveyable to the measured gas space (13), and at least one diffusion barrier (12) arranged between the gas inlet opening (17) and measured gas space (13). The diffusion barrier (12) includes at least one layer (14, 14a, 14b) of catalytically active material for establishing equilibrium in the gas mixture.

Abstract: To improve the electrical properties of the gas sensor, the following measures may be used:

Abstract: An electrochemical sensor for ascertaining a gas concentration of a measuring gas includes an electrochemical element, including a first solid electrolyte body having an electrochemical pump cell and a first and a second electrode, and having a gas compartment which is connected via a gas access opening to the measuring-gas compartment, and in which one of the two electrodes is arranged. The electrochemical element further includes a second solid electrolyte body having an electrochemical sensor cell (Nernst cell) and a third and a fourth electrode. The surface of the first solid electrolyte body faces the measuring-gas compartment, and the gas access opening is covered by a porous protective layer. The electrochemical sensor includes a layer that exhibits a higher density or a lower porosity compared to the protective layer and that is allocated to the porous protective layer.

Abstract: A gas sensor and a method for its manufacture are described. The gas sensor has a solid electrolyte having at least one measuring electrode and one porous protective coating. The measuring electrode has an electrically conductive base layer and a further layer, the further layer god being deposited in the pores of the porous protective coating adjacent to the base layer via galvanic deposition. In order to deposit the further layer via galvanic deposition, the basic body, which has been fused with the base layer and the protective coating via vitrification, is immersed in a galvanizing bath, the base layer being connected as the cathode.

Abstract: A gas sensor and a method for its manufacture are described. The gas sensor has a solid electrolyte (11) having at least one measuring electrode (15) and one porous protective coating (16). The measuring electrode (15) has an electrically conductive base layer (25) and a further layer (27), the further layer (27) being deposited in the pores of the porous protective coating (16) adjacent to the base layer (25) via galvanic deposition. In order to deposit the further layer (27) via galvanic deposition, the basic body (10), which has been fused with the base layer (25) and the protective coating (16) via vitrification, is immersed in a galvanizing bath, the base layer (25) being connected as the cathode.

Abstract: An electrochemical sensor for ascertaining a gas concentration of a measuring gas includes an electrochemical element, including a first solid electrolyte body having an electrochemical pump cell and a first and a second electrode, and having a gas compartment which is connected via a gas access opening to the measuring-gas compartment, and in which one of the two electrodes is arranged. The electrochemical element further includes a second solid electrolyte body having an electrochemical sensor cell (Nernst cell) and a third and a fourth electrode. The surface of the first solid electrolyte body faces the measuring-gas compartment, and the gas access opening is covered by a porous protective layer. The electrochemical sensor includes a layer that exhibits a higher density or a lower porosity compared to the protective layer and that is allocated to the porous protective layer.

Abstract: An electrochemical sensor measures a gas concentration of a measured gas with an electrochemical element. The electrochemical sensor includes an electrochemical pump cell with a first solid electrolyte body, a first and a second electrode, and a gas chamber, which is connected to a measured gas chamber via a gas inlet opening and in which one of the two electrodes is located. The electrochemical sensor also includes a second solid electrolyte body with an electrochemical sensor cell (e.g., a Nernst cell), which has a third electrode and a reference gas chamber in which a fourth electrode is located, with the electrodes having a supply conductor for electrical contacting. A supply conductor of the fourth electrode is provided with an electrically insulating layer to insulate it against the second solid electrolyte body.

Abstract: An electrochemical sensor determining a gas concentration of the measuring gas. The sensor has an electrochemical element including a first solid electrolyte body having an electrochemical pump cell and a first (external pump) and a second (internal pump) electrode and having a gas chamber which is connected to the measuring gas chamber via a gas supply opening and in which the second electrode is arranged. The electrochemical element also includes a second solid electrolyte body having an electrochemical sensor cell (e.g., a Nernst cell) and a third and fourth electrode, each electrode having a lead for the electrical contacting. The leads of the first and second electrodes are decoupled capacitively from the lead of at least the fourth electrode by a device.

Abstract: In order to provide a method and arrangement for analytical determination of the relative amounts of exhaust gas components, except for water, but including hydrogen in the rich range or oxygen in the lean range, and for determining a &lgr; value, in which the exhaust gas sample can be taken at any arbitrary location, an arrangement is provided in which at least one portion of the exhaust gas is passed through a catalytic reactor (2, 22), a condenser (3,23) connected to the catalytic reactor to receive the gas passed through it, and, after passing through the condenser, the gas passes through an IR spectrometer and by a &lgr;-sensor. The oxidizable and reducible components of the exhaust gas are reacted with each other in the catalytic reactor which is heated to temperatures greater than 450° C.