Flow sensing device

Patent metadata

Field	Value
Publication number	US-12044561-B2
Application number	US-202017090990-A
Country	US
Kind code	B2
Filing date	Nov 6, 2020
Priority date	Nov 6, 2020
Publication date	Jul 23, 2024
Grant date	Jul 23, 2024

Abstract

Methods and apparatuses associated with flow sensing devices are provided. An example flow sensing device includes a flow cap component and a sensor component. The flow cap component or sensor component may include a heating element. The flow cap component can at least partially define a flow channel configured for a media to flow therethrough. The heater element may be orthogonal or perpendicular to the flow channel. The sensor component may include at least one thermal sensing element disposed upstream of the heater element and at least one thermal sensing element disposed downstream of the heater element. The sensor component may include two or more thermal sensing elements disposed in either the upstream direction or downstream direction of the heater element. Thermal sensing elements may be spaced different distances from the heater element to increase the accuracy and precision of flow rate measurement at low flow rates.

First claim

The invention claimed is:

1. A flow sensor comprising:
a flow channel configured to transport a fluid therethrough, the flow channel being disposed along a first axis;
a heating element disposed nearby the flow channel, wherein the heating element is configured to release a predetermined amount of thermal energy, a center of the heating element being disposed along a second axis at least substantially perpendicular to the first axis; one or more first thermal sensing elements disposed along the first axis a first distance from the center of the heating element, wherein changes in a voltage differential between an inlet and an outlet of the one or more first thermal sensing elements are indicative of changes in a temperature at the one or more first thermal sensing elements; and
one or more second thermal sensing elements disposed along the first axis a second distance from the center of the heating element, the second distance being greater than the first distance, wherein changes in the voltage differential between an inlet and an outlet of the one or more second thermal sensing elements are indicative of changes in the temperature at the one or more second thermal sensing elements,
wherein the flow sensor is configured to determine a flow rate of the fluid through the flow channel based upon an association between a sum of the first and second voltage differential and the flow rate of fluids through the flow channel, and
wherein the first distance is between about 25 μm and about 75 μm, and wherein said second distance from the heating element is between about 125 μm and about 175 μm.

2. The flow sensor of claim 1 , wherein the one or more first thermal sensing elements and the one or more second thermal sensing elements are positioned upstream or downstream of the heating element.

3. The flow sensor of claim 2 , further comprising circuitry configured to at least:
determine a sum the first and second voltage differentials; and
compare said sum of the first and second voltage differentials to a calibration curve, said calibration curve relating a plurality of summed voltage differentials to said flow rate of the fluid.

4. The flow sensor of claim 1 , wherein said one or more first thermal sensing elements or said one or more second thermal sensing elements comprise at least one from among: a resistor, a resistive bridge, a diode, a resistive Wheatstone bridge, a thermocouple, or a thermopile.

5. The flow sensor of claim 1 , wherein said one or more first thermal sensing elements are disposed said first distance from the center of the heating element in an upstream direction relative to a flow direction of the fluid in the flow channel, wherein said one or more second thermal sensing elements are disposed said second distance from the center of the heating element in the upstream direction relative to the flow direction of the fluid in the flow channel, and wherein the flow sensor further comprises:
one or more third thermal sensing elements disposed the first distance from the center of the heating element in a downstream direction relative to the flow direction of the fluid in the flow channel; and
one or more fourth thermal sensing elements disposed the second distance from the center of the heating element in a downstream direction relative to the flow direction of the fluid in the flow channel.

6. The flow sensor of claim 1 , further comprising:
a sensor component comprising a top surface and defining an inner cavity; and
a membrane disposed on a portion of the top surface of the sensor component, wherein the one or more first thermal sensing elements and the one or more second thermal sensing elements are disposed on or within the membrane.

7. The flow sensor of claim 6 , wherein each thermal sensing element of said one or more first thermal sensing elements and said one or more second thermal sensing elements comprise a first thermocouple material operably coupled at a first end to a thermocouple contact, and a second thermocouple material operably coupled at a first end to the thermocouple contact.

8. The flow sensor of claim 7 , wherein the thermocouple contact is positioned said first distance from the center of the heating element, and wherein a second end of the first thermocouple material and a second end of the second thermocouple material extend beyond an edge of the membrane.

9. The flow sensor of claim 1 , wherein the flow channel has a height or a diameter that is between about 1 μm and about 500 μm.

10. The flow sensor of claim 1 , wherein the flow sensor is configured to measure flow rates between about 0.1 mL/hour and about 1,000 mL/hour.

11. The flow sensor of claim 1 , wherein said heating element has a width between about 5 μm and about 100 μm, and wherein the heating element has a length between about 50 μm and about 1,000 μm.

12. The flow sensor of claim 1 , wherein said one or more first thermal sensing elements are configured to be electrically coupled to said one or more second thermal sensing elements.

13. A flow sensor comprising: a flow cap component at least partially defining a flow channel, wherein the flow channel is configured to transport a fluid therethrough, the flow channel being disposed substantially along a first axis; a sensor component comprising a top surface and defining an inner cavity, the flow cap being operably coupled to at least a portion of the top surface of the sensor component, the sensor component comprising: a heating element disposed on or within said sensor component, the heating element being disposed along a second axis at least substantially perpendicular to the first axis; a first thermal sensing element disposed on or within said sensor component along said second axis and spaced a first distance in a first direction from a center of the heating element, wherein a first output voltage is measurable at an outlet of the first thermal sensing element; a second thermal sensing element disposed on or within said sensor component along said second axis and spaced a second distance in the first direction from the center of the heating element, the second distance being greater than the first distance, wherein a second output voltage is measurable at an outlet of the second thermal sensing element; a third thermal sensing element disposed on or within said sensor component along said second axis and spaced the first distance in a second direction from the center of the heating element, the second direction being opposite the first direction, wherein a third output voltage is measurable at an outlet of the third thermal sensing element; and a fourth thermal sensing element disposed on or within said sensor component along said second axis and spaced the second distance in the second direction from the center of the heating element, wherein a fourth output voltage is measurable at an outlet of the fourth thermal sensing element, wherein a voltage differential between a sum of the first and second output voltages and a sum of the third and fourth output voltages is indicative of a flow rate of the fluid through the flow channel, wherein each of the first, second, third, and fourth thermal sensing elements comprise a first thermocouple material operably coupled at a second end to a thermocouple contact, and a second thermocouple material operably coupled at a first end to the thermocouple contact, and wherein a distance between the second end of the first thermocouple material and the center of the heating element is about 25 μm and about 75 μm, and a distance between a second end of the second thermocouple material and the center of the heating element is about 125 μm and about 175 μm.

1

Assignees

• Honeywell Int Inc

Inventors

• Beck Scott Edward
• Speldrich Jamie W
• Speldrich Brian D
• Foster Philip C

Classifications

• G01F1/696

  Circuits therefor, e.g. constant-current flow meters · CPC title

• G01F1/692

  Thin-film arrangements · CPC title

• G01F1/69

  of resistive type · CPC title

• G01F1/6888 Primary

  Thermoelectric elements, e.g. thermocouples, thermopiles · CPC title

• G01F1/688

  using a particular type of heating, cooling or sensing element {(G01F1/6847 takes precedence)} · CPC title