FLOW SENSOR

• US 20150000655A1
• Filed: 06/28/2013
• Published: 01/01/2015
• Est. Priority Date: 06/28/2013
• Status: Active Grant

• Current Assignee: Vyaire Medical Capital LLC
• Original Assignee: Carefusion 303 Incorporated (Becton, Dickinson & Co)
• Inventors: DESILVA, Adrian D., VU, Huy Thanh, MILLER, Jeffrey Harold, LE, Richard, GONZALEZ, Hector, VALDEZ, Raul, WANG, Chiun
• Granted Patent: US 9,746,359 B2
• Time in Patent Office: Days
• US Class Current: 128/203.14
• CPC Class Codes: A61M 16/0066 Blowers or centrifugal pumps
• CPC Class Codes: A61M 16/021 operated by electrical means A61M16/202 – A61M16/205 take precedence
• CPC Class Codes: A61M 16/1045 Devices for humidifying or heating the inspired gas by using recovered moisture or heat from the expired gas
• CPC Class Codes: A61M 16/12 by mixing different gases
• CPC Class Codes: A61M 16/16 Devices to humidify the respiration air A61M16/1045 takes precedence
• CPC Class Codes: A61M 2016/0027 pressure meter
• CPC Class Codes: A61M 2016/0039 in the inspiratory circuit
• CPC Class Codes: A61M 2202/0208 Oxygen
• CPC Class Codes: A61M 2202/025 Helium
• CPC Class Codes: A61M 2205/3368 Temperature
• CPC Class Codes: A61M 2205/3569 sublocal, e.g. between console and disposable
• CPC Class Codes: A61M 2205/3592 using telemetric means, e.g. radio or optical transmission
• CPC Class Codes: A61M 2205/505 Touch-screens; Virtual keyboard or keypads; Virtual buttons; Soft keys; Mouse touches
• CPC Class Codes: G01F 1/36 the pressure or differential pressure being created by the use of flow constriction
• CPC Class Codes: G01F 1/50 Correcting or compensating means

Abstract

A flow sensor comprises a flow restriction disposed within a passage such that a fluid passing through the passage must pass through the flow restriction. The flow sensor also has an upstream pressure sensor coupled to the passage at a point upstream of the flow restriction and configured to measure and provide an upstream pressure of the fluid within the passage, a downstream pressure sensor coupled to the passage at a point downstream of the flow restriction and configured to measure and provide a downstream pressure of the fluid within the passage, and a temperature sensor coupled to the passage and configured to measure and provide a temperature of the fluid within the passage. The flow sensor also includes a flow sensor processor coupled to the upstream and downstream pressure sensors and the temperature sensor and configured to accept measurements therefrom and calculate a compensated flow rate based at least in part on the measured pressures and temperature.

Claims

1. A flow sensor comprising:

a flow restriction disposed within a passage such that a fluid passing through the passage must pass through the flow restriction;

an upstream pressure sensor coupled to the passage at a point upstream of the flow restriction and configured to measure and provide an upstream pressure of the fluid within the passage;

a downstream pressure sensor coupled to the passage at a point downstream of the flow restriction and configured to measure and provide a downstream pressure of the fluid within the passage;

a temperature sensor coupled to the passage and configured to measure and provide a temperature of the fluid within the passage; and

a flow sensor processor coupled to the upstream and downstream pressure sensors and the temperature sensor and configured to accept measurements therefrom and calculate a compensated flow rate based at least in part on the measured pressures and temperature.

2. The flow sensor of claim 1, further comprising a non-volatile memory coupled to the flow sensor processor and configured to store executable instructions and compensation parameters, wherein:

the flow sensor processor is configured by retrieving the executable instructions from the memory to further retrieve the compensation parameters from the memory; and

the calculation of the compensated flow rate is based at least in part of the retrieved compensation parameters.

3. The flow sensor of claim 2, wherein:

the flow sensor processor is further configured to accept an identification of the fluid that is passing through the passage;

the compensation parameters comprise characteristics of the flow restriction that are related to a plurality of predetermined fluids;

the retrieved compensation parameters comprise characteristics of the flow restriction related to the identified fluid; and

the calculation of the compensated flow rate is based at least in part on the retrieved compensation parameters that are related to the identified fluid.

4. The flow sensor of claim 3, wherein the characteristics of the flow restriction are determined for each of the plurality of predetermined fluids.

5. The flow sensor of claim 4, wherein the plurality of predetermined fluids comprises one or more medical gases.

6. The flow sensor of claim 5, wherein the plurality of predetermined fluids comprises one or more of a standard composition of ambient air, a pure oxygen, and a heliox gas mixture.

7. The flow sensor of claim 4, wherein the characteristics of the flow restriction are experimentally determined for one or more of the plurality of predetermined fluids.

8. The flow sensor of claim 4, wherein the characteristics of the flow restriction are determined for each of the plurality of predetermined fluids over a range of temperatures.

9. The flow sensor of claim 4, wherein range of temperatures comprises at least 5-50°

C.

10. The flow sensor of claim 1, wherein the flow restriction comprises a porous disk.

11. A method comprising the steps of:

identifying a fluid passing through a flow restriction;

measuring a pressure drop across the flow restriction;

retrieving compensation parameters that comprise information associated with characteristics of the identified fluid flowing through the flow restriction; and

calculating with a processor a compensated flow rate.

12. The method of claim 11, further comprising the step of:

measuring a temperature of the fluid; and

wherein the compensation parameters further comprise information associated with the characteristics of the identified fluid flowing through the flow restriction at the measured temperature.

13. The method of claim 11, wherein the step of identifying the fluid comprises accepting a signal from an external system that identifies the fluid.

14. The method of claim 11, wherein the step of retrieving compensation parameters comprises retrieving the compensation parameters from a non-volatile memory.

15. The method of claim 11, further comprising the step of:

downloading with a processor a set of executable instructions, thereby configuring the processor.

16. A ventilator comprising:

an output flow channel configured to mate with a supply limb;

an input flow channel configured to accept a gas from a source; and

a flow sensor comprising;

a flow restriction disposed within a passage coupled between the input flow channel and the output flow channel such that the gas passing through the passage must pass through the flow restriction;

an upstream pressure sensor coupled to the passage at a point upstream of the flow restriction and configured to measure and provide an upstream pressure of the gas within the passage;

a downstream pressure sensor coupled to the passage at a point downstream of the flow restriction and configured to measure and provide an downstream pressure of the gas within the passage;

a temperature sensor coupled to the passage and configured to measure and provide a temperature of the gas within the passage; and

a flow sensor processor coupled to the upstream and downstream pressure sensors and the temperature sensor and configured to accept measurements therefrom and calculate a compensated flow rate based at least in part on the measured pressures and temperature.

17. The ventilator of claim 16, further comprising a non-volatile memory coupled to the flow sensor processor and configured to store executable instructions and compensation parameters, wherein:

the flow sensor processor is configured by retrieving the executable instructions from the memory to further retrieve the compensation parameters from the memory; and

the calculation of the compensated flow rate is based at least in part of the retrieved compensation parameters.

18. The ventilator of claim 16, further comprising:

a gas inlet adapter having an orientation uniquely associated with the gas being supplied to the input flow channel;

a sensor configured to detect the orientation of the gas inlet adapter; and

a central processor coupled to the sensor and the flow sensor processor, the central processor configured to identify the gas that will be passing through the flow sensor from the detected orientation of the gas inlet adapter,

wherein;

the flow sensor processor is further configured to accept an identification of the gas that is passing through the flow sensor;

the compensation parameters comprise characteristics of the flow restriction that are related to a plurality of predetermined gases;

the retrieved compensation parameters comprise characteristics of the flow restriction related to the identified gas; and

the calculation of the compensated flow rate is based at least in part on the retrieved compensation parameters that are related to the identified gas.

19. The ventilator of claim 18, wherein the characteristics of the flow restriction are determined for each of the plurality of predetermined gases.

20. The ventilator of claim 19, wherein the plurality of predetermined gases comprises one or more medical gases.

21. The ventilator of claim 20, wherein the plurality of predetermined gases comprises one or more of a standard composition of ambient air, a pure oxygen, and a heliox gas mixture.

22. The ventilator of claim 19, wherein the characteristics of the flow restriction are experimentally determined for one or more of the plurality of predetermined gases.

23. The ventilator of claim 19, wherein the characteristics of the flow restriction are determined for each of the plurality of predetermined gases over a range of temperatures.

24. The ventilator of claim 23, wherein range of temperatures comprises at least 5-50°

C.

25. The ventilator of claim 16, wherein the flow restriction comprises a porous disk.