Siemens Aktiengesellschaft

Michael Ludwig

Ludwig Kimmig

Peter Krause

Camiel Heffels

Ralf Bitter

Thomas Hörner

Florian Kirsammer

Peter Lindmuller

Günter Marcaux

Hans-Guenther Kleih

Martin Kionke

Dieter Huller

Guenter Marcaux

Hans-Günther Kleih

Karlheinz Schmidt

A gas analyzer for a gas mixture with at least three components includes a channel guiding the gas mixture, a thermoelement probe with a measuring point in the interior of the channel and a cold junction in thermal contact with the channel wall, a control device for pulsed activation of the thermoelement probe, a measuring device for measuring voltage at the cold junction in pauses between current pulses, and an evaluation device for determining temperature differences and calculating the ratio of the components of the gas mixture from temperature difference values determined at different time instant pauses, wherein the control device generates current pulses with at least two different energy contents and the temperature difference values at the first time instant in the pause after a current pulse with a higher energy content and used for the calculation is higher than with a current pulse with a lower energy content.

Thermal conductivity detector for gas mixtures having at least three components

A measuring device in which a non-electrical variable is converted into an electrical measurement signal via an electrical alternating current having a frequency, wherein the measurement signal contains a signal portion dependent on the non-electrical variable and is double the frequency, and a fault signal portion dependent on the alternating current and is at the frequency, where the measurement signal is pre-processed and digitized to generate a digital signal that is detected and processed to generate a measured value proportional to the non-electrical variable and to generate a fault signal value, wherein the fault signal value is utilized to normalize the measured value that is normalized in a normalizing stage, by forming the quotient using the square of the fault signal value, and is output as a normalized measured value.

Measuring device

A heatable flow-through measuring cell for a gas analyzer having an inner tube made of a corrosion-resistant material, such as stainless steel, and is terminated at each end with a respective end piece and a radiolucent window held therein. The measuring cell also includes an electrical heating apparatus for heating each end piece, an outer tube that coaxially surrounds the inner tube so as to form a narrow gap and is made of material with good thermal conductivity, such as aluminum, and includes thermal insulation that surrounds the outer tube.

Heatable flow-through measurement cell

A lock-in amplifier with an additional phase-sensitive detector is provided. A measurement signal is mixed in a multiplicative fashion with a reference signal, which is phase-shifted by 90 degrees, for a modulation frequency. In order to reliably filter out interference signal portions in a widest possible dynamic range and, at the same time, minimize unavoidable influence on the useful signal portion, a control device is connected downstream of the additional phase-sensitive detector. The control device determines a control variable corresponding to the strength of the interference signal from the measurement signal mixed with the reference signal phase shifted by 90 degrees and uses the control variable to change the integration duration of the integrator proportionally to the control variable, a corresponding cut-off frequency of an equivalent low pass being coordinated automatically.

Lock-in amplifier and method for filtering a measurement signal using such an amplifier

The invention relates to a NDIR-gas analyser comprising an infrared radiation source (), a measuring vessel () containing a gas mixture () having a measuring gas component () that is to be detected, and a detector device () that is arranged behind the measuring vessel that can detect the influence of ageing of the radiation source () and optionally dirt deposits in the optical radiation path without interrupting measuring. According to the invention, at least one optopneumatic detector () is arranged in the beam path of the radiation source (), said detector being filled with any gas () when arranged between the radiation source () and the measuring vessel (). The concentration of measuring gas components is lower in the detector () than in the measuring vessel () if filled with the measuring gas components, and said detector is filled with a gas when arranged between the measuring vessel () and the detector device (), the absorption spectrum of the detector being outside of the spectrum of the measuring gas components () and other transversal gases in the gas mixture (). The measuring signal () of the detector device () is corrected by the detector signal () generated by the detector ().

Non-dispersive infrared gas analyzer

The aim of the invention is to reduce the apparatus-related complexity and the mounting effort in a process absorption spectrometer taking in situ measurements. Said aim is achieved by providing the process absorption spectrometer with a unit comprising a source of radiation and at least one additional unit encompassing a detector, both units being embodied as pieces of field equipment and being connected to a field bus.

Process absorption spectrometer

An exhaust gas analysis is to be performed, in a manner that is largely automatic, on motor vehicles having an on-board engine control and diagnostic system (OBD ) and equipped with a diagnostic interface ( ). To this end, control commands ( ) are generated, preferably in an exhaust gas tester ( ), and are transmitted via the diagnostic interface ( ) to the engine control and diagnostic system ( ). The engine control and diagnostic system ( ), in accordance with the control commands ( ), adjusts the operating states of the motor vehicle ( ) that are prescribed for the exhaust gas analysis.

Method and arrangement for performing an exhaust gas analysis on motor vehicles having an on-board engine control and diagnostic system

A non-dispersive infrared gas analyzer for determining concentrations of carbon dioxide and/or carbon monoxide, hydrocarbons, and nitrogen oxides has two measuring cells 4, 6 consecutively traversed by a beam, with an optopneumatic detector 22 for carbon dioxide and an optopneumatic detector 23 for carbon monoxide arranged between them. Detectors 7, 8 for hydrocarbons and nitrogen oxides are arranged on the measuring cell 6 located downstream from detectors 22, 23 in the direction of the beam.

In a distance measurement to an object, the distance measurement operating according to the FMCW principle, a linear frequency-modulated signal is transmitted and mixed with the signal reflected back from the object, generating a demodulation signal with a frequency proportional to the distance. To determine the distance, at least one estimation signal with an assumed frequency and a variable phase is generated and an estimation error is determined by comparison of the transmitted signal and the estimation signal. The phase of the estimation signal is adaptively varied for the purpose of an error reduction and the frequency of the estimation signal is corrected corresponding to the variation of the phase over time, the distance being determined from the frequency corrected in this manner.

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Karlsruhe, Germany

Michael Ludwig