Robert Boschgmbh

Martin Lenfers

Lothar Diehl

Johann Riegel

Walter Strassner

Johannes Locher

Harald Neumann

Olaf Jach

Hannes Pflug

Josef Steiner

Werner Auth

Harry Braun

Hans-J Peter

Michel Friedbert

J&uuml;rgen Schwarz

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. A joint supply conductor resistor of the Nernst electrode and of the inner pump electrode is formed by a loaded voltage divider whose individual resistors are arranged so that the negative feedback of a Nernst voltage circuit and of a pump voltage circuit is optimized, in particular maximized.

Measurement sensor for determining an oxygen concentration in a gas mixture

A sensor element for determining the concentration of a gas component in a gas mixture, particularly for determining the oxygen concentration in exhaust gases of internal combustion engines. The sensor element includes at least one pump cell, which has at least one first pump electrode located in a measuring gas chamber and at least one second pump electrode, located on a surface of the sensor element facing the gas mixture, as well as at least one concentration cell, which has at least one reference electrode located in a reference gas chamber and at least one measuring electrode, located in the measuring gas chamber, which cooperates with the reference electrode. The measuring gas chamber and the reference gas chamber are essentially located in the same layer level (plane) of the sensor element which has a layered construction. At least one barrier layer is provided which, at least to a large extent, prevents ionic conduction between at least one electrode of the pump cell and at least one electrode of the concentration cell.

Electrochemical sensor element

In a method of controlling a sensor for determining an oxygen concentration in a gas mixture, in particular in the exhaust gas of internal combustion engines, a detection voltage supplied by a Nernst measurement cell and corresponding to the oxygen concentration is transformed by a circuit arrangement into a pump voltage for a pump cell, and an anodic or cathodic limit current flows over the pump cell, depending on the oxygen content of the gas mixture. In stable operation of the sensor, during which an anodic limit current flows for a selectable period of time, the pump cell and/or the Nernst measurement cell receives at least one voltage pulse supplied independently by the measured detection voltage or the pump current thus established, so that the sensor is depolarized.

Method of controlling a sensor for determining an oxygen concentration in a gas mixture

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.

Electrochemical sensor

A device for temperature measurement at an oxygen probe, in particular a lambda probe, having a solid electrolyte arranged between two electrodes. At least one of the electrodes is provided with two spaced terminals for measuring an electrical resistance of the electrodes.

Device for temperature measurement at an oxygen probe

The reaction heat sensor and control and analysis devices for measuring the concentration of reactive species in a medium includes a temperature dependent measuring resistor and a reference resistor connected in series. Both resistors, which are supplied with a constant alternating current by a constant current generator, are heated with a heating resistor. By analysis of the voltage drop at the reference resistor the heating resistor is regulated so that the temperature of the reference resistor and thus its reference resistance is kept constant. Thus it is guaranteed by control circuitry that the temperature of the measuring resistance is kept constant when no heat is generated by reaction on exposure to the medium. If a reaction occurs at the measuring resistor, the temperature of the measuring resistance changes and with it the voltage drop across the measuring resistor, which is analyzed and is a direct measure of the heat produced by the reaction.

Control and analysis circuit device for measuring reaction heat

A glow plug electrically heated during start-up to help bring the air-fuel mixture of an internal combustion engine to ignition temperature when the engine is cold, instead of being turned off as soon as the engine is running, has its heating current controlled so as to maintain the glow plug temperature within a desired range, as the result of which the engine can be made to run more quietly and more smoothly under many conditions. The current control unit which varies the glow plug current responds to the output signal of a computing unit responsive to various engine operation parameters, including especially a signal representative of the rate of feeding fuel to the engine.

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Aidlingen, Germany

Martin Lenfers