Fluid sensor including substantially linear flow resistor
AssigneeHewlett-Packard Company
InventorHans-Georg Haertl
Life of this patent
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Abstract
The volumetric flow rate of a fluid is determined essentially independently of the properties of the fluid by guiding the volumetric fluid flow to be measured through an essentially linear flow resistor. An alternating flow of the fluid is superimposed on the volumetric fluid flow to be measured. Steady and alternating components of a pressure drop across the flow resistor are detected. A quantity representative of a property of the fluid is determined in response to the determined alternating component. The volumetric flow rate is calculated on the basis of the determined steady component and the quantity representing fluid property.
Claims19
A fluid sensor comprising:
- an essentially linear flow resistor arranged in a fluid flow;
- a differential pressure sensor arranged in parallel to the flow resistor and which produces a differential pressure signal (.DELTA.p);
- and
- a pump means arranged in parallel to the flow resistor and the differential pressure sensor for superimposing an alternating flow on the flow to be measured.
A device for determining the viscosity of a fluid, comprising:
- a fluid sensor including:
- an essentially linear flow resistor arranged in a fluid flow;
- a differential pressure sensor arranged in parallel to the flow resistor for deriving a differential pressure signal;
- and
- a pump means arranged in parallel to the flow resistor and the differential pressure sensor and constructed so it is capable of superimposing an alternating flow on the flow to be measured;
- and
- a signal evaluation means for determining a viscosity representative value on the basis of the alternating differential pressure signal generated by the differential pressure sensor and which is essentially proportional to the alternating flow.
A device for determining the volumetric flow rate of a fluid, comprising:
- a fluid sensor including:
- an essentially linear flow resistor arranged in a fluid flow;
- a differential pressure sensor arranged in parallel to the flow resistor for producing a differential pressure signal;
- a pump means arranged in parallel to the flow resistor and the differential pressure sensor for superimposing an alternating flow on the flow to be measured;
- and
- a volumetric flow rate determination means for deriving a quantity representative of a fluid property from the alternating differential pressure signal which is generated by the differential pressure sensor and which is essentially proportional to the alternating flow, and which derives the volumetric flow rate from the steady component of the differential pressure signal generated by the differential pressure sensor as well as from the quantity representative of the fluid property.
A method of determining the volumetric flow rate of a fluid, comprising the steps of:
- guiding the volumetric flow rate to be measured through an essentially linear flow resistor;
- generating an alternating fluid flow and superimposing the same on the volumetric fluid flow to be measured;
- detecting the pressure drop across the flow resistor;
- determining the steady component and the alternating component of the detected pressure drop;
- determining a quantity representative of a fluid property of the fluid on the basis of the determined alternating component;
- and
- calculating the volumetric flow rate on the basis of the determined steady component and on the basis of the quantity representative of the fluid property.
A method of determining the viscosity of a fluid, comprising the steps of:
- inserting an essentially linear flow resistor in the fluid whose viscosity is to be determined;
- imposing an alternating flow of the fluid in the flow resistor;
- detecting the alternating component of the pressure drop across the flow resistor;
- and
- determining the viscosity of the fluid on the basis of the detected alternating component.
Dependencies are inferred from the claim text.