Flow direction detector

• US 20040031331A1
• Filed: 08/14/2002
• Published: 02/19/2004
• Est. Priority Date: 08/14/2002
• Status: Active Grant

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Inventors: Orr, David, Blakley, Daniel R.
• Granted Patent: US 6,871,535 B2
• Time in Patent Office: Days
• US Class Current: 73/862.52
• CPC Class Codes: A61M 15/009 using medicine packages with incorporated spraying means, e.g. aerosol cans pocket atomiser of the injector type A61M11/08
• CPC Class Codes: A61M 2016/0039 in the inspiratory circuit
• CPC Class Codes: G01F 1/6842 with means for influencing the fluid flow
• CPC Class Codes: G01F 1/696 Circuits therefor, e.g. constant-current flow meters
• CPC Class Codes: G01F 1/72 Devices for measuring pulsing fluid flows
• CPC Class Codes: G01F 13/006 measuring volume in function of time
• CPC Class Codes: G01F 5/00 Measuring a proportion of the volume flow

Abstract

A flow direction detector is provided which includes a flow disruptor positioned in a fluid flow path to effect a detectable differential flow characteristic to such flow path based on fluid flow direction, and a sensor arrangement configured to detect such detectable differential flow characteristic within the flow path.

Claims

1. A flow direction detector comprising:

a flow disrupter positioned in a fluid flow path to effect a detectable differential flow characteristic to such flow path based on fluid flow direction; and

a sensor arrangement configured to detect such detectable differential flow characteristic within the flow path.

2. The flow direction detector of claim 1, wherein the detectable differential flow characteristic is temperature.

3. The flow direction detector of claim 2, wherein the sensor arrangement includes a first temperature sensor.

4. The flow direction detector of claim 3, wherein the first temperature sensor is disposed along the flow path in a direction detection region characterized by differing temperatures under differing directions of fluid flow.

5. The flow direction detector of claim 1, wherein the detectable differential flow characteristic is mass flow rate.

6. The flow direction detector of claim 5, wherein the fluid disrupter is configured to promote fluid flow across the direction detection region upon fluid flow in a first direction, and to promote fluid flow bypass of the direction detection region upon fluid flow in a second direction, the sensor arrangement being configured to detect corresponding differential mass flow rates in the direction detection region.

7. The flow direction detector of claim 1, wherein the fluid disruptor includes a mound and a ledge configured to promote laminar fluid flow across an intermediate direction detection region upon fluid flow in the first direction, and to promote non-laminar fluid flow over the direction detection region upon fluid flow in the second direction, and wherein the sensor arrangement includes a first temperature sensor disposed within the direction detection region, the first temperature sensor being affected differentially by such laminar and non-laminar fluid flows.

8. The flow direction detector of claim 7, wherein the fluid disrupter further includes a foil configured to further promote laminar fluid flow across the first temperature sensor upon fluid flow in the first direction, and to promote fluid flow bypass of the first temperature sensor upon fluid flow in the second direction, thereby enhancing differential sensed temperature based on fluid flow direction.

9. The flow direction detector of claim 1, wherein the sensor arrangement includes a first temperature sensor disposed in a direction detection region characterized by temperatures dependant on direction of fluid flow, and a second temperature sensor disposed in a flow region characterized by temperatures substantially independent of the direction of fluid flow.

10. The flow direction detector of claim 9, which further comprises a comparator configured to compare temperatures sensed by the first and second temperature sensors, a temperature sensed by the first temperature sensor which is lower than a temperature sensed by the second temperature sensor being indicative of fluid flow in the first direction.

11. The flow direction detector of claim 9, which further comprises a comparator configured to compare temperatures sensed by the first and second temperature sensors, a temperature sensed by the first temperature sensor which is higher than a temperature sensed by the second temperature sensor being indicative of fluid flow in the second direction.

12. The flow direction detector of claim 1, wherein the sensor arrangement includes a first transistor pair including a reference transistor and a first sense transistor disposed along the flow path in a direction detection region characterized by differing mass flow rates under differing directions of fluid flow, the first sense transistor being operatively linked to the reference transistor in a feedback loop to provide for differing control voltages under such differing mass flow rates.

13. The flow direction detector of claim 12, wherein the sensor arrangement further includes a second transistor pair including the reference transistor and a second sense transistor disposed along the flow path in a flow region characterized by a mass flow rate substantially independent of the direction of fluid flow, the second sense transistor being operatively linked to the reference transistor in a feedback loop to provide a reference control voltage corresponding to such direction-independent mass flow rate, comparison of the control voltage to the reference control voltage being indicative of a direction of fluid flow.

14. The flow direction detector of claim 13, wherein the first and second transistor pairs share a reference transistor.

16. The flow direction detector of claim 14, wherein the fluid disruptor includes a mound and a ledge configured to promote turbulent laminar fluid flow across the direction detection region upon fluid flow in the first direction, and to promote less-turbulent eddy fluid flow in the direction detection region upon fluid flow in the second direction.

17. The flow direction detector of claim 16, wherein the fluid disruptor further includes a foil configured to further promote turbulent laminar fluid flow across the first temperature sensor upon fluid flow in the first direction, and to further promote less-turbulent eddy fluid flow across the first temperature sensor upon fluid flow in the second direction, thereby enhancing differential sensed temperature based on fluid flow direction.

15. A flow direction detector comprising:

a flow disruptor positioned in a fluid flow path to promote turbulent fluid flow in a direction detection region upon fluid flow in a first direction, and to promote less-turbulent eddy fluid flow in the direction detection region upon fluid flow in a second direction, thereby providing for a detectable differential temperature in the direction detection region based on fluid flow direction;

a sensor arrangement including a first temperature sensor disposed in the direction detection region wherein temperature has a first relation to direction of fluid flow and a second temperature sensor disposed in a flow region wherein temperature has a second relation to direction of fluid flow; and

a comparator configured to effectively compare temperatures sensed by the first and second temperature sensors, a temperature sensed by the first temperature sensor which is lower than a temperature sensed by the second temperature sensor being indicative of fluid flow in the first direction.

18. The flow direction detector of claim 15, wherein the first and second temperature sensors are dual anemometers configured to provide temperature indications based on mass flow rates.

19. A flow direction detector comprising:

a flow disruptor configured to promote laminar fluid flow across a direction detection region upon fluid flow in a first direction, and to promote eddy fluid flow in the direction detection region upon fluid flow in a second direction, thereby effecting detectable differential mass flow rate in the direction detection region based on fluid flow direction;

a sensor arrangement including a first sense element disposed in the direction detection region wherein mass flow rate is dependant on direction of fluid flow and a second sense element disposed in a flow region wherein mass flow rate is substantially independent of direction of fluid flow, the first sense element being characterized by a direction-detecting control signal dependent on mass flow rate in the direction detection region and the second sense element being characterized by a reference control signal dependent on mass flow rate in the flow region; and

a comparator configured to compare control signals of the first and second sense elements, wherein a first detected relation between such control signals is indicative of fluid flow in the first direction and a second detected relation between such control signals is indicative of fluid flow in a second direction.

20. The flow direction detector of claim 19, wherein the first sense element includes a first sense transistor, the first sense transistor being operatively linked to a reference transistor in a feedback loop to provide for differing direction-sensing control signals under differing mass flow rates.

21. The flow direction detector of claim 20, wherein the second sense element includes a second sense transistor, the second sense transistor being operatively linked to the reference transistor in a feedback loop to provide for differing reference control signals under differing mass flow rates.

22. A method of detecting fluid flow direction along a bi-directional fluid flow path comprising:

disrupting fluid flow in a direction detection region along the fluid flow path differentially based on direction of fluid flow, such differential fluid flow disruption having a corresponding differential effect on temperature within the direction detection region during fluid flow;

sensing temperature within the direction detection region during such fluid flow;

sensing temperature in a flow region outside of the direction detection region during such fluid flow; and

comparing the sensed temperature in the direction detection region with the sensed temperature in the flow region, wherein a first detected relation between such sensed temperatures is indicative of fluid flow in the first direction and a second detected relation between such sensed temperatures is indicative of fluid flow in a second direction.

23. A method of detecting fluid flow direction along a fluid flow path comprising:

altering mass flow rate of fluid flow in a direction detection region differentially based on direction of fluid flow;

sensing a first mass flow rate of fluid within the direction detection region during such fluid flow;

sensing a second mass flow rate of fluid in a flow region outside of the direction detection region during such fluid flow; and

comparing the first mass flow rate with the second mass flow rate, wherein determination of a first relation between the first mass flow rate and the second mass flow rate is indicative of flow in a first direction.

24. The method of claim 23, wherein sensing mass flow rate within the direction detection region is via a first anemometer.

25. The method of claim 24, wherein sensing mass flow rate within the flow region is via a second anemometer.

26. A flow direction detector comprising:

a flow disruptor means for promoting turbulent fluid flow in a direction detection region of a fluid flow path upon fluid flow in a first direction, and for promoting less-turbulent eddy fluid flow in the direction detection region upon fluid flow in a second direction, thereby providing for a detectable differential temperature in the direction detection region based on fluid flow direction;

a sensor arrangement including a first temperature sensing means disposed in the direction detection region wherein temperature is dependent on direction of fluid flow and a second temperature sensing means disposed in a flow region wherein temperature is substantially independent of direction of fluid flow; and

a comparator means configured to effectively compare temperatures sensed by the first and second temperature sensing means, a first relation between a temperature sensed by the first temperature sensing means and a temperature sensed by the second temperature sensing means being indicative of fluid flow in the first direction.

27. A method of detecting fluid flow direction in a tube defining a bi-directional fluid flow path, the method comprising:

forming a monolithic control circuit having first and second sense transistors disposed along the fluid flow path and a reference transistor isolated from the fluid flow path;

operatively linking each sense transistor to the reference transistor in respective first and second feedback loops to provide for respective first and second control signals based on respective temperature relationships between each sense transistor and the reference transistor;

selectively disrupting fluid flow adjacent the first sense transistor based on actual direction of fluid flow, such selective fluid flow disruption having a corresponding differential effect on temperature relationship between the first sense transistor and the reference transistor;

comparing the first and second control signals, a first detected relation between such control signals being indicative of fluid flow in the first direction and a second detected relation between such control signals being indicative of fluid flow in a second direction.

28. The method of claim 27, wherein forming the monolithic control circuit includes forming such monolithic circuit in a delivery tube of a metered dose inhaler to accommodate detection of proper delivery of inhalant from such metered dose inhaler.

29. A metered dose inhaler comprising:

a delivery tube defining a fluid flow path along which an inhalant is delivered to a user;

a flow disrupter disposed within the delivery tube to promote turbulent fluid flow across a direction detection region upon fluid flow in a first direction, and to promote eddy fluid flow in the direction detection region upon fluid flow in a second direction, thereby effecting detectable differential mass flow rate in the direction detection region based on fluid flow direction;

a sensor arrangement including a first sense element disposed in the direction detection region wherein mass flow rate is dependant on direction of fluid flow and a second sense element disposed in a flow region wherein mass flow rate is substantially independent of direction of fluid flow, the first sense element being characterized by a direction-detecting control signal dependent on mass flow rate in the direction detection region and the second sense element being characterized by a reference control signal dependent on mass flow rate in the flow region; and

a comparator configured to compare control signals of the first and second sense elements, wherein a first detected relation between such control signals is indicative of fluid flow in the first direction and a second detected relation between such control signals is indicative of fluid flow in a second direction.

30. A method of detecting inhalation in a metered dose inhaler, the method comprising:

disrupting inhalant flow in a detection region of a delivery based on direction of inhalant flow within the detection region, such differential flow disruption having a corresponding differential effect on temperature within the detection region during inhalant flow;

sensing temperature within the detection region during such inhalant flow;

sensing temperature in a flow region outside of the detection region during such inhalant flow; and

comparing the sensed temperature in the detection region with the sensed temperature in the flow region, wherein a first detected relation between such sensed temperatures is indicative of inhalation.

31. The method of claim 30, which further comprises comparing timing of a dosing directive of the metered dose inhaler with timing of detected inhalation to verify proper delivery of inhalant to a user.

32. The method of claim 31, which further comprises indicating to proper delivery of inhalant to the user.

33. The method of claim 31, which further comprises storing information regarding propriety of successive detected dosing events in memory to record a history of metered dose inhaler use.

34. The method of claim 33, which further comprises periodically communicating such recorded history of metered dose inhaler use to a physician.

35. A flow direction detector comprising:

a flow disruptor positioned in a fluid flow path to effect a detectable differential flow characteristic to such flow path based on fluid flow direction; and

a sensor arrangement including plural sets of sense elements, each set of sense elements being arranged along a different flow axis to detect such detectable differential flow characteristic along such flow axis, whereby a vector sum of such detected flows along such different flow axes yields flow direction.