Abstract: A sensor element of a gas sensor is used for determining the concentration of hydrogen or a hydrogen-containing gas component, preferably ammonia or hydrocarbons, present in a gas mixture. It has a measuring electrode (13) exposed to the gas mixture and at least one reference electrode (14), both electrodes being applied to a proton-conducting solid electrolyte (11a), the solid electrolyte (11a) being made of a purely ceramic material.

Abstract: An electrochemical measuring sensor for selectively determining nitrogen oxides in a gas mixture including oxygen and nitrogen oxides, includes a solid electrolyte layer; a cover layer; and a diffusion channel which is defined between the solid electrolyte layer and the cover layer, and through which the gas mixture diffuses in a diffusion direction. The solid electrolyte layer has provided on a surface thereof a first cathode and a second cathode disposed one after the other in the diffusion direction of the gas mixture within the diffusion channel and exposed to the gas mixture in the order recited, and has provided on an opposite surface thereof at least one anode. The diffusion channel forms a diffusion barrier for the second cathode. The first and second cathodes and the at least one anode are gas permeable and consist of one of a precious metal or a precious metal alloy. The first cathode is provided with a coating which completely covers same, which is impermeable to nitrogen oxides (NO.sub.

Abstract: The invention relates to a method and a circuit arrangement for actuating a measuring sensor for determining an oxygen concentration in a gas mixture, particularly in exhaust gases of internal combustion engines, wherein a detector voltage corresponding to the oxygen concentration and supplied by a reference probe is transferred into a pump voltage for a measuring probe by a circuit arrangement.It is provided that a curve of the detector voltage (U.sub.D) is used directly for determining the curve of the pump voltage (U.sub.P), with a first input (38) of the circuit arrangement (36) being connected to a first input (46) of an adder (48) at whose second input (50) an add voltage is applied and whose output (54) is connected to the second input (40) of the circuit arrangement (36) via an amplifier (58).

Abstract: A measuring sensor for determining oxygen content in a gas mixture including exhaust gases of internal combustion engines, includes a base substrate which is comprised of a base material and which is electrically insulating; and an electrochemical measuring probe and an electrochemical reference probe arranged separate from each other on the base substrate. The measuring probe includes at least one internal electrode; at least one solid electrolyte island; and at least one external electrode. The measuring probe additionally includes a diffusion barrier. Further base material layers composed of the base material are provided so as to embed at least the diffusion barrier, the at least one internal electrodes for the measuring probe and the internal electrode for the reference probe. A diffusion hole is defined between the measuring probe and the reference probe which extends from the base substrate through the diffusion barrier and respective base material layers, and out to the gas mixture to be measured.

Abstract: A polarographic sensor for determining concentration of certain components including oxygen or combustible fractions, such as hydrocarbons, hydrogen and carbon monoxide, in the exhaust gas of an internal combustion engine, includes a pump cell having an anode, a cathode, and an oxygen ion-conducting solid electrolyte provided between the anode and the cathode, wherein the cathode is provided with a diffusion barrier, wherein the anode is provided with a diffusion barrier, and wherein the concentration of the certain components is determined by measurement of a limiting current through the electrolyte and across one of the diffusion barriers to the corresponding anode or cathode.

Abstract: A sensor arrangement for determining at least one of gas components and gas concentrations of gas mixtures including CO, NO.sub.x and HC in exhaust gases of internal combustion engines, includes a measuring element which has a sensitive region; and a pump cell that includes a solid electrolyte and inner and outer pump electrodes which are opposingly disposed at least on the solid electrolyte and which effect an oxygen transfer to the measuring element, wherein the pump cell and the measuring element are spatially separated from one another, are located in different temperature zones during operation of the sensor arrangement, and are connected to one another by a diffusion segment through which oxygen can diffuse from the pump cell to the measuring element.

Abstract: The invention relates to a measuring sensor having pump reference for measuring the oxygen content of gas mixtures, particularly exhaust gases of internal combustion engines. The sensor includes a measuring cell (A) and a reference cell (B) each having a pair of electrodes, with one of each respective pairs of electrodes being common to the two cells, and having a fixed electrolyte. Reference cell (B) has defined therein an internal oxygen reference zone which is hermetically sealed from the gas mixture and which is connected to the atmosphere by way of a pressure-equalization line. The measuring cell (A) and the reference cell (B) can be heated by heating apparatus to a temperature at which the fixed electrolyte has an ionic conductivity which is sufficiently high.

Abstract: Sensor element for limiting current sensors to determine the lambda value of gas mixtures, in particular of exhaust gases of internal combustion engines, having inner and outer pump electrodes disposed on a ceramic substrate, the inner pump electrode of which is accessible for the measurement gas supplied through a diffusion layer acting as a diffusion barrier; having a gas-tight cover layer above the diffusion layer and having conductor tracks for the pump electrodes is described, in which the diffusion layer is adjustable, to calibrate the sensor element. This adjustability is advantageously attained by embodying the side of the diffusion layer 5 oriented toward the measurement gas inlet opening as a zigzag-shaped adjustment zone 8, from which parts can be separated mechanically or by laser cuts. The invention makes comparatively simple calibration of sensor elements possible.

Abstract: A sensor element is proposed for an oxygen limiting current probe for the determination of the .lambda. value of gas mixtures, particularly the exhaust gases of internal-combustion engines, whose oxygen supply is provided by a short-circuit cell disposed upstream of the pumping cell of the sensor element. In this way the CO.sub.2 and H.sub.2 O transverse sensitivity of the sensor element is made ineffective. In order to obtain at the pumping cell a limiting current that is a linear function of the O.sub.2 partial pressure, a diffusion barrier must additionally be disposed between the short-circuit cell and the pumping cell.

Abstract: To permit calibrating and testing a current-limiting sensor in situ, the sensor is exposed, from time to time, to ambient air forming a standard gas, and the output thereof compared with a standard, for example by connecting a resistor (4) of standard value in circuit therewith or for recalling from a memory (23) in a microcomputer (22) standard conditions; upon determination of a deviation between output from the sensor (2) when exposed to the standard gas--typically air--and the theoretical value as stored, the theoretical or reference value is reset if the deviation is within a predetermined limit or, otherwise, an alarm output is provided. The tolerance limits can be set in such a way that a first alarm output is provided in a narrow tolerance, thus indicating drift of the sensor toward eventual malfunction, and permitting utilization of the sensor for long lifetime, while providing advance warning of imminent failure.

Abstract: To permit simultaneous evaluation of the light as a consequence of combustion in the combustion chamber of an internal combustion (IC) engine, and evaluation of the oxygen content of the combustion gas resulting from the combustion, a tubular housing of generally spark-plug shape is closed off at the end facing the combustion chamber by a solid electrolyte body in form of a disk (6), closed tube or thimble (6c) or the like, which is made of transparent zirconium dioxide. The interior of the housing has a light guide (7) extending therein. The solid electrolyte body has electrodes (11, 11'; 11c, 11'c) applied thereto, electrically connected to an electrical evaluation stage (EE) to determine oxygen concentration in the combustion gases, while the light due to combustion is transmitted through the solid electrolyte to the light guide for evaluation in an optical evaluation stage (EO).

Abstract: To provide for temperature measurement of a solid electrolyte polarographic gas composition sensor, an ac signal is superimposed from an ac voltage source (2) on the applied voltage from a voltage source (1) if the sensor is a polarographic sensor, the ac signal being separated from the output by a filter combination (6, 7), the dc output being evaluated as usual, and the ac output being rectified in a rectifier (9) to obtain a measure of the temperature since the ac resistance (R.sub.alt) is highly temperature dependent (see FIG. 3). The ac preferably is about 10% of the applied dc voltage, so that the voltage swing of the ac potential falls well within the linear range of output current with respect to voltage (see FIG. 2). The output from the ac channel (7, 9) to evaluate the temperature signal can be connected to a control loop circuit (10, 11), including a heater (11) to heat the sensor to maintain a uniform temperature thereof.

Abstract: A method and apparatus is proposed for obtaining a control variable for the closed-loop control of the fuel-air ratio of the operating mixture of internal combustion engines, in which a threshold-current sensor of known structure is used. By means of varying the measurement voltage present at the threshold-current sensor by voltage amounts which correspond to a change in oxygen concentration to be expected in association with a change in operational state, the time behavior of the threshold-current sensor, which is essentially sluggish, is compensated for and it becomes possible to use it for rapidly-functioning closed-loop control systems in internal combustion engines.

Abstract: A solid electrolyte is sandwiched between a measuring electrode exposed to the gas and a reference electrode exposed to a reference gas of known oxygen level, and a cover, for example in form of a layer or a cap, is applied over the measuring electrode.

Abstract: To permit a layer construction, which is inexpensive and lends itself to mass production manufacture, a solid electrolyte body, in plate-like construction, with electrodes at either thereof is positioned in a housing with a portion thereof extending in the region where it is exposed to gases to be sensed; a porous cover is applied on one of the electrodes, the porous cover having a predetermined diffusion resistance to oxygen molecules. A flat insulating plate of approximately the same dimension as the solid electrolyte plate is positioned flat thereagainst, and a flat layer-like electrical heating element is secured on the flat insulating plate or, in other embodiments, against another insulating covering on the other side of the heating element as well, close to the electrodes and adjacent the plane surfaces of the body.

Abstract: To facilitate manufacture of a sensor, particularly a polarographic sensor which has no sealing or heat expansion difficulties and only low heat capacity in the measuring range and electrical connections, a solid electrolyte (17) is formed as a plate extending transversely across a bottom opening (13) of a preferably ceramic tube (11), the plate having two electrodes (16,21) applied to its major sides. The side facing the opening (13) is covered with a ceramic layer (20) having a predetermined diffusion or migration resistance to oxygen molecules. The electrical connections are formed by a conductive track (15) extending on the inside of the ceramic tube, in contact with the sensing electrode on one side of the plate; and a counter head (23) connected to a conductive bolt or pin (24) and resiliently spring pressed against the electrode, and holding the plate (17) and the diffusion barrier (20) thereon in position in the sensor.

Abstract: To simplify manufacture and provide a polarographic sensor of high response speed, operating according to the current limiting principle, an oxygen molecule migration barrier is provided leading to the cathode by separating the cathode from the space where the gas to be tested exists by a wall through which a hole is provided which extends therethrough to a small space immediately above the cathode defined by support elements placed immediately on the cathode. The hole, or a plurality of holes, is so dimensioned that the diameter thereof, with respect to its length, is small, with diameters of between 0.01 to 0.06 mm and a length of at least about 1 mm being suitable.

Abstract: To measure partial oxygen pressure in gases, particularly exhaust gases of automotive-type combustion engines, a solid electrolyte plate of elongated rectangular configuration has at least one electrode pair applied to a single surface thereof, which is exposed to the measuring gas. Preferably, the gap between electrodes is elongated, by forming the electrodes in comb-interdigited form. A thermocouple - temperature sensor can be applied between connecting tracks for the electrodes which extend longitudinally of the electrolyte plate towards the other end thereof, through a sealing mass holding the plate within a housing, the other end forming, simultaneously, a connection terminal for connection to an electric connector or plug. A heating element can be placed on the obverse side of the plate, preferably in the position in the gap between the electrodes.

Abstract: Between 0.001 and 0.5% by weight of polytetrafluoroethylene powder is incorporated in the composite electrochemically active mass carried on the lead plates of a lead-acid storage battery. In the case of the positive electrodes, the result is to lengthen the service life in terms of cycles of charging and discharging. In the case of the negative electrodes, the effect is to raise the low-current yield and the low-temperature high-current yield. The density of the composite mass is reduced and its water-holding properties increased.

Abstract: A lightweight catalyst body bearing a finely divided metal of the platinum group is encased in a porous PTFE shell which is impermeable to the electrolyte because of its hydrophobic surface properties. Several small bodies of this kind, each containing about 1 mg of palladium are inserted in each cell of a vehicle storage battery and float on the electrolyte surface. They not only recombine hydrogen and oxygen to water and return the water to the electrolyte efficiently, even at high ambient temperatures, but the efficiency of the catalyst is not reduced under conditions causing considerable generation of stibine. The core material on which the catalyst is provided, with or without an additional carrier, may be activated charcoal, hollow glass spheres, a porous ceramic or a synthetic resin foam. The porous hydrophobic shell may be sintered or unsintered or may be made of superimposed sintered and unsintered layers.