Gas viscosity sensor
AssigneeEcole Polytechnique Federale de Lausanne
InventorsPeter Ryser, Sigfrid Straessler
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Abstract
A gas viscosity sensor comprises a signal processing circuit and a sensor element, including a gas pressure generating system and a differential pressure measuring system in fluid communication therewith, the differential pressure measuring system comprising a measuring chamber (14) bounded by a thin membrane (28), an inlet-outlet channel or orifice interconnecting the measuring chamber to a source of gas for which the viscosity is to be determined, the inlet-outlet channel or orifice having dimensions adapted to provide resistance to the outflow and inflow of gas in the measuring chamber, and a membrane displacement sensor (32) adapted to measure a time dependent displacement of the membrane due to pressure variations in the measuring cavity.
Claims22
Gas viscosity sensor comprising:
- a signal processing circuit and a sensor element including a gas pressure generating system and a differential pressure measuring system in fluid communication therewith, the differential pressure measuring system comprising;
- a measuring chamber bounded by a thin membrane,
- a displacement sensor adapted to measure a time dependent displacement of the membrane due to pressure variations in the measuring cavity, and
- an inlet-outlet channel or orifice interconnecting the measuring chamber to a source of gas for which viscosity is to be determined,
- wherein the inlet-outlet channel or orifice is dimensioned to provide resistance to outflow and inflow of gas in the measuring chamber,
- the membrane displacement sensor comprises a heat sensitive sensor positioned on the thin membrane, and opposed thereto a heat sink, and
- the signal processing circuit is adapted to process the measured time-dependent displacement in order to obtain a parameter dependent on the viscosity of the gas.
Gas viscosity sensor comprising
- a signal processing circuit and a sensor element including a gas pressure generating system and a differential pressure measuring system in fluid communication therewith, the differential pressure measuring system comprising
- a measuring chamber bounded by a thin membrane,
- a displacement sensor adapted to measure a time dependent displacement of the membrane due to pressure variations in the measuring cavity, and
- an inlet-outlet channel or orifice interconnecting the measuring chamber to a source of gas for which viscosity is to be determined,
- wherein the inlet-outlet channel or orifice having dimensions adapted to provide resistance to an outflow and inflow of gas in the measuring chamber,
- the pressure generating system includes an expansion chamber separate from the measurement chamber;
- and
- the signal processing circuit is adapted to process the measured time-dependent displacement to obtain a parameter dependent on the viscosity of the gas.
Dependencies are inferred from the claim text.