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EP-4445934-B1 - FLOW PATH SENSING FOR FLOW THERAPY APPARATUS

EP4445934B1EP 4445934 B1EP4445934 B1EP 4445934B1EP-4445934-B1

Inventors

  • BURGESS, Russel William
  • DONNELLY, Jess Edward
  • BARKER, DEAN ANTHONY
  • DICKINSON, PHILIP JOHN
  • VAN SCHALKWYK, Andre
  • LAWSON, Joel Michael

Dates

Publication Date
20260513
Application Date
20161202

Claims (11)

  1. A gas delivery system, the system comprising: a housing (100), the housing containing a blower (2001), the blower comprising a motor configured to generate a gas flow; a humidifier (12) to humidify the gas flow; one or more sensors (2008) configured to determine gases properties of the gas flow in a flow path of the gas delivery system; a first pressure sensor positioned within the housing of the gas delivery system and outside the flow path, and configured to determine a first absolute pressure, wherein the first absolute pressure is an estimate of ambient pressure; a second pressure sensor (2209) positioned within a sensor module of the gas delivery system, and configured to determine a second absolute pressure of the gases in the flow path after the gas flow has been generated by the blower, wherein the gas delivery system is configured such that after passing through the flow path in the sensor module, the gas flow exits to the humidifier; the gas delivery system further comprising: a controller (13), configured to receive output from the one or more sensors, the first pressure sensor, and the second pressure sensor (2209); wherein the controller (13) is configured to calculate a differential pressure based on the difference between the first and second absolute pressures; the controller (13) being further configured to adjust the motor speed curve of the blower (2001) based on the differential pressure and correct control of a flow rate of the gases; wherein the sensor module comprises a sensing chamber (2007), and wherein the flow path of the gas delivery system directs the gas flow through the flow path of the sensing chamber; and wherein the sensing chamber (2007) comprises a sensing circuit board (2200) and wherein the second pressure sensor (2209) is positioned on the sensing circuit board (2200) and in the flow path of the sensing chamber (2007).
  2. The gas delivery system of Claim 1, wherein the second pressure sensor (2209) is downstream of the blower (2001).
  3. The gas delivery system of any of Claims 1 to 2, wherein the controller (13) is further configured to estimate a pressure generated by the blower (2001) based on the calculated differential pressure.
  4. The gas delivery system of any of Claims 1 to 3, wherein the controller (13) is further configured to compare a mass flow rate with a volumetric flow rate based on the ambient pressure.
  5. The gas delivery system of Claim 4, wherein the controller (13) is further configured to: determine based on the second absolute pressure a density of the gases needed to convert between the volumetric flow rate and the mass flow rate; determine an accuracy of the one or more sensors (2008) based on a comparison between the mass flow rate and the volumetric flow rate; and make corrections to the readings of the one or more sensors (2008) based on the accuracy of the one or more sensors determined.
  6. The gas delivery system as claimed in any of Claims 1 to 5, wherein the adjustment to the motor speed curve is to synchronize the motor speed with a patient's breath.
  7. The gas delivery system of any of Claims 1 to 6, wherein the controller (13) is further configured to calculate limits for detecting blockage and leakage at different altitudes based on the first and second absolute pressures.
  8. The gas delivery system of any of Claims 6 or 7, wherein the controller (13) is further configured to make corrections to humidity calculation based at least on the second absolute pressure, the second pressure sensor allowing corrections to be made in response to the partial pressure of water vapour in the gas.
  9. The gas delivery system of any of Claims 1 to 8, wherein the one or more sensors (2008) configured to determine gases properties comprise ultrasonic transducers.
  10. The gas delivery system of any of Claims 1 to 9, wherein the system comprises a heated temperature sensing element (2206) configured to measure a flow rate of the gases in the flow path of the gas delivery system.
  11. The gas delivery system of any of Claims 9 or 10, wherein the controller (13) is configured to use output from the one or more sensors to provide redundancy of flow measurement, the redundancy comprising fast flow measurement at low flows by the ultrasonic transducer of the one or more sensors and accurate flow measurement at low flows by the heated temperature sensing element of the one or more sensors.

Description

FIELD OF THE DISCLOSURE The present disclosure relates to methods and systems for flow path sensing in a flow therapy apparatus for delivering gas to patients. Background Breathing assistance apparatuses are used in various environments such as hospital, medical facility, residential care, or home environments to deliver a flow of gas to users or patients. A breathing assistance apparatus, or a flow therapy apparatus, may include a valve used to deliver oxygen with the flow of gas, and/or a humidification apparatus to deliver heated and humidified gases. A flow therapy apparatus may allow adjustment and control over characteristics of the gas flow, including flow rate, temperature, gas concentration, humidity, pressure, etc. Sensors, such as heated temperature sensing elements and/or thermistors, are used to measure these properties of the gases. Patent document US 2004/0211423 A1 is acknowledged SUMMARY The scope of the invention is defined by the appended claims. The present disclosure describes a flow therapy apparatus where a flow of gases is measured through at least a portion of the flow path. The portion of the flow path can be configured to be continuously curved such that there are no significant angles. The flow path can comprise an entrance, a horizontal portion, and an exit, wherein the entrance and the exit can be positioned in vertically opposed directions, and the horizontal portion is positioned between the entrance and the exit. The horizontal portion can have a smooth curve along the entire length of the horizontal portion. The flow path can further comprise one or more sensors positioned within the flow path and configured to measure the flow of gases through the portion of the flow path. The one or more sensors can comprise one or more of an ultrasonic transducer or gas concentration sensor. The one or more sensors can be configured to sense flow rate and/or oxygen concentration. The one or more sensors can be located in a sensor module. The flow path can be further configured to have a total flow distance between 50 mm and 150 mm. The flow path can also be further configured to have an average cross-sectional diameter between 10 mm and 20 mm. The flow path can further comprise a first cross-sectional area at the first end of the flow path; a second cross-sectional area at the second end of the flow path; and a middle cross-sectional area between the first end and second end of the flow path, wherein the middle cross-sectional area can be less than the first cross-sectional area, and wherein the middle cross-sectional area can be less than the second cross-sectional area. The one or more sensors can be located after a blower. The blower can be a mixer. The one or more sensors can further include a heated temperature sensing element configured to measure flow rate of the gases, and/or temperature, humidity, humidity and temperature, and/or pressure sensors. Also described is a flow path of gases to prevent unwanted vorticity in the flow of gases that can create anomalies in measuring flow rate. The flow path can be used in conjunction with the ultrasonic sensor system. The present disclosure describes a flow therapy apparatus that can comprise an inlet port which receives a flow of gases from at least two different gas sources; a blower which receives the flow of gases from the inlet port, where the blower is configured to mix the flow of gases from the different gas sources to produce mixed gases; a gases flow path which receives the mixed gases from the blower and directs the gases flow through a sensor chamber; and one or more sensors, where the sensors are configured to measure one or more properties of the flow of gases flowing through the gases flow path. The one or more sensors can be located after the blower. The blower can be a mixer. The one or more sensors can be located in a sensor module. The different gas sources can comprise oxygen gas, and the inlet port can comprise a valve configured to deliver a flow of the oxygen gas to the blower. The valve can comprise a proportional valve. The one or more sensors can comprise two or more ultrasonic transducers. The one or more sensors can also comprise a gas concentration sensor. The ultrasonic transducers can be configured to determine a gas concentration. The ultrasonic transducers can be configured to determine a flow rate. The one or more sensors can comprise a heated temperature sensing element configured to measure gases flow rate. The present disclosure describes a sensing chamber in a flow therapy apparatus that can comprise a flow path configured to accommodate a flow of gases; and one or more sensors configured to measure a property of the flow of gases flowing through the flow path, wherein the sensors can comprise a first ultrasonic transducer positioned at a downstream portion of the flow path, and a second ultrasonic transducer positioned at an upstream portion of the flow path, and wherein the flow path can be configu