A flow sensor for determining the velocity and direction of a fluid flow including a substrate, a heat source located on the substrate, and a first and a second heat sensor located on the substrate to detect at least a portion of heat generated by the heat source. The first and second heat sensors and the heat source are arranged in a non-linear orientation.

Fluid flow sensor

A rugged microsensor assembly is disclosed that measures both the velocity and angular direction of an incoming air stream. The microsensor assembly includes at least two flow sensors, each orientated to measure a different velocity component of the incoming air stream. The velocity components are related by the geometry between the sensors, and the angular direction and velocity of the incoming air stream are determined by examining the measured velocity components. The preferred sensor is a fully passivated thermal differential microanemometer with back contacts, designed to operate in harsh environments.

Microsensor for measuring velocity and angular direction of an incoming air stream

Flow sensor assemblies having increased flow range capabilities are disclosed. In one illustrative embodiment, a flow sensor assembly includes a housing with an inlet flow port, an outlet flow port, a fluid channel extending between the inlet flow port and the outlet flow port, and a bypass channel having a pair of taps fluidly connected to the fluid channel at separate locations. A flow sensor for sensing a measure related to a flow rate of a fluid flowing through the fluid channel can positioned in the bypass channel. A pressure differential between the two taps of the bypass channel can drive a fraction of a fluid flowing through the fluid channel through the bypass channel. The flow sensor assembly may be configured to achieve, control, and/or balance a desired fraction of fluid flow through the bypass channel and past the flow sensor.

Flow sensor assembly with integral bypass channel

A thermal fluid flow or property sensor having no exposed contact wires or contact pads in the fluid flow path to obstruct measurements, flat fully passivated sensor surfaces and high corrosion resistance is implemented over a honeycombed thermal isolation chamber.

Rugged fluid flow and property microsensor

The present disclosure relates to methods and devices for reducing moisture, dust, particulate matter, and/or other contaminates entering a sensor. A sensor assembly may include a housing with an inlet flow port and an outlet flow port. The housing may define a fluid channel extending between the inlet flow port and the outlet flow port, with a sensor positioned in the housing and exposed to the fluid channel. The sensor may be configured to sense a measure related to the flow rate of a fluid flowing through the fluid channel. A hydrophobic filter may be situated in the fluid channel, sometimes upstream of the sensor. When so configured, and during operation of the sensor assembly, a fluid may pass through the inlet flow port, through the hydrophobic filter, across the sensor, and through the outlet flow port.

Sensor assembly with hydrophobic filter

A thermal mass flow meter includes a comb-shaped structure having a plurality closely spaced septa carried from a common spine and disposed within the flow stream to be measured for partitioning the flow therein into a plurality of generally parallel elongated ribbon-shaped flow stream portions. Temperature-dependent fluid flow sensing resistor means is coupled in heat-exchanging relation predominantly with the narrow face of at least one of said ribbon-shaped flow stream portions for measuring the fluid flow. In a preferred embodiment, the comb-shaped flow partitioning structure is fabricated by anisotropically etching the parallel flow channels through the (110) face of diamond cubic material such as silicon. In another embodiment, a thermal loading member is disposed in heat-exchanging relation with the temperature dependent fluid flow sensing resistor means for thermally loading same and pushing the critical flow rate up to a higher flow to allow operation of the flow sensor in one mode of operation over a wider range of flow rates.

Harry E. Aine

Papers

Thermal mass flow meter and method of making same