US 7,922,884 B2Granted

Device for measuring the pressure in a gas mixture

AssigneeRobert Bosch GmbH

InventorsRainer Strohmaier, Martin Bauer, Bernhard Kamp

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Abstract

A device for measuring the pressure of a gas mixture composed of gas components has an amperometric sensor that works on the limiting current principle, having two electrodes connected to a direct voltage that are situated on a solid electrolyte, of which one electrode is covered by a diffusion barrier, and a measuring element for measuring the limiting current flowing via electrodes as a measure for the gas pressure. For the purpose of error-free measurement of the gas pressure in a gas mixture in which the concentration of the gas components fluctuates with time, means are provided which fix the mole fraction of a gas component, drawn upon for pressure measurement, that is present upstream of the diffusion barrier at a constant 100%, at least during the pressure measuring phase. In one preferred exemplary embodiment, these means include a storage volume that is adjacent to the diffusion barrier which is separated from the gas mixture by a diffusion path, and two electrodes, situated on the solid electrolyte, for pumping of the gas component into the storage volume.

Claims20

Dependent claims

A device for measuring pressure in a gas mixture, comprising:

an amperometric sensor that operates according to a limiting current principle, the sensor including two first electrodes mounted on a solid electrolyte, a direct voltage being applied to the first electrodes, wherein one of the first electrodes is shielded by a diffusion barrier;
a measuring element configured to measure the limiting current flowing via the first electrodes as a measure of the gas pressure;
and
an arrangement configured to fix, at least during a pressure measuring phase, a mole fraction of a gas component drawn upon for the pressure measurement upstream of the diffusion barrier to a constant 100%,
wherein the arrangement includes a storage volume for the gas component, the storage volume be arranged in front of the diffusion barrier in the solid electrolyte, a diffusion path closing off the storage volume in a direction of the gas mixture, the arrangement further including two second electrodes situated at the solid electrolyte to pump the gas component all the way through the solid electrolyte into the storage volume,
wherein the sensor includes a Nernst cell made up of a solid electrolyte and two second electrodes situated thereon, a first one of the second electrodes being a measuring electrode and being situated in a measuring chamber developed in the solid electrolyte, and a second one of the second electrodes being a reference electrode and being exposed to a pumped oxygen reference in a reference gas channel developed in the solid electrolyte;
and
a pump cell made up of a solid electrolyte and two pump electrodes situated thereon, an outer one of the pump electrodes situated thereon, an outer one of the pump electrodes being exposed to the exhaust gas and an inner one of the pump electrodes being situated in the measuring chamber;
wherein the reference gas channel is provided with an opening that is exposed to the exhaust gas, and wherein in the reference gas channel between the reference electrode and the opening, the diffusion path and the storage volume are developed, and an outer one of the pump electrodes and the reference electrode being used as intervals for pumping oxygen and for measuring gas pressure by switching over their voltage potentials.

6 more elements

A sensing element for determining oxygen concentration in exhaust gas of an internal combustion engine, comprising:

a Nernst cell made up of a solid electrolyte and two electrodes situated thereon, a first one of the electrodes being a measuring electrode and being situated in a measuring chamber developed in the solid electrolyte, and a second one of the electrodes being a reference electrode and being exposed to a pumped oxygen reference in a reference gas channel developed in the solid electrolyte;
a pump cell made up of the solid electrolyte and two pump electrodes situated thereon, an outer one of the two pump electrodes being exposed to the exhaust gas and an inner one of the pump electrodes being situated in the measuring chamber;
and
an integrated device for measuring pressure in the exhaust gas, the device configured as the sensing element, electrodes of the sensing element used as at least on of the two first electrodes of the amperometric sensor and to pump the gas component, the device including:
an amperometric sensor that operates according to a limiting current principle, the sensor including two first electrodes mounted on a solid electrolyte, a direct voltage being applied to the electrodes, wherein one of the first electrodes is shielded by a diffusion barrier;
a measuring element configures to measure the limiting current flowing via the first electrodes as a measure of the gas pressure;
and
an arrangement configured to fix, at least during a pressure measuring phase, a mole fraction of a gas component drawn upon for the pressure measurement upstream of the diffusion barrier to a constant 100%.

5 more elements

Dependencies are inferred from the claim text.

Facts

Application: 10/578,339Filed 8 Nov 2004
Priority: DE 103 52 79712 Nov 2003
Published: US 2007/0144904 A128 Jun 2007
Granted: 12 Apr 2011
Term ends: Not estimatedThe source records don’t support an estimate.

Classification4 codes

G01N 27/407
Cells and probes with solid electrolytes: for investigating or analysing gases
G01L 13/06
Devices or apparatus for measuring differences of two or more fluid pressure values: using electric or magnetic pressure-sensitive elements
G01N
Investigating or analysing materials by determining their chemical or physical properties
G01L
Measuring force, stress, torque, work, mechanical power, mechanical efficiency, or fluid pressure