Gases mixing and measuring for a medical device

Patent metadata

Field	Value
Publication number	US-2017197056-A1
Application number	US-201515313836-A
Country	US
Kind code	A1
Filing date	May 27, 2015
Priority date	May 27, 2014
Publication date	Jul 13, 2017
Grant date	—

Abstract

A gases humidification system includes a measuring chamber and a mixing chamber. The mixing chamber has one or more mixing elements that improve a mixing of gases before reaching the measuring chamber. Ultrasonic sensing is used to measure gases properties or characteristics within the measuring chamber. A baffle or a vane may be used to control and direct the gases flow through the mixing chamber as the gases flow moves into the measuring chamber.

First claim

What is claimed is:

1 . A gases measurement apparatus comprising:
a gases measuring chamber comprising a gases flow path from a first end of the gases measuring chamber to a second end of the gases measuring chamber, wherein a downstream direction is defined along the gases flow path from the first end to the second end and an upstream direction is defined along the gases flow path from the second end to the first end; a controller; a first ultrasonic sensor positioned at the first end of the gases measuring chamber, the first ultrasonic sensor configured to transmit a downstream acoustic pulse train in a first measurement phase, to detect an upstream acoustic pulse train in a second measurement phase, and to send a signal to the controller; and a second ultrasonic sensor positioned at the second end of the gases measuring chamber, the second ultrasonic sensor configured to transmit the upstream acoustic pulse train in the second measurement phase, to detect the downstream acoustic pulse train in the first measurement phase, and to send a signal to the controller; wherein the controller is configured to determine a characteristic of the gases based at least in part on a signal received from the first ultrasonic sensor and a signal received from the second ultrasonic sensor.

2 . The apparatus of claim 1 , wherein the gases comprise two gases.

3 . The apparatus of claim 2 , wherein the two gases comprise oxygen and air.

4 . The apparatus of claim 1 , wherein the downstream acoustic pulse train or the upstream acoustic pulse train comprises a plurality of acoustic pulses.

5 . The apparatus of claim 1 , wherein the downstream acoustic pulse train or the upstream acoustic pulse train comprises a single acoustic pulse.

6 . The apparatus of claim 1 , wherein the characteristic of the gases comprises at least one of gases concentration, flow rate, or velocity.

7 . The apparatus of claim 1 , wherein the first and second ultrasonic sensors are configured to be excited at a natural resonant frequency.

8 . The apparatus of claim 1 , wherein the controller is configured to determine a downstream time of flight for the downstream acoustic pulse train, the controller is configured to determine an upstream time of flight for the upstream acoustic pulse train, and the controller is configured to determine the characteristic of the gases based at least in part on the downstream time of flight and the upstream time of flight.

9 . A method for determining a characteristic of gases flowing through an apparatus along a gases flow path from a first end of the apparatus to a second end of the apparatus, the apparatus comprising a first ultrasonic sensor positioned at the first end and a second ultrasonic sensor positioned at the second end, a downstream direction defined along the gases flow path from the first end to the second end and an upstream direction defined along the gases flow path from the second end to the first end, the method comprising:
transmitting a downstream acoustic pulse train from the first ultrasonic sensor and detecting the downstream acoustic pulse train at the second ultrasonic sensor; determining a downstream time of flight based at least in part on the downstream acoustic pulse train; transmitting an upstream acoustic pulse train from the second ultrasonic sensor and detecting the upstream acoustic pulse train at the first ultrasonic sensor; determining an upstream time of flight based at least in part on the upstream acoustic pulse train; and determining the characteristic of the gases based at least in part on the downstream time of flight and the upstream time of flight.

10 . The method of claim 9 , wherein the downstream acoustic pulse train or the upstream acoustic pulse train comprises a plurality of acoustic pulses.

11 . The method of claim 9 , wherein the downstream acoustic pulse train or the upstream acoustic pulse train comprises a single acoustic pulse.

12 . The method of claim 9 , comprising:
transmitting a second downstream acoustic pulse train from the first ultrasonic sensor and detecting the second downstream acoustic pulse train at the second ultrasonic sensor; determining the downstream time of flight based at least in part on an average of the downstream acoustic pulse train and the second downstream acoustic pulse train; transmitting a second upstream acoustic pulse train from the second ultrasonic sensor and detecting the second upstream acoustic pulse train at the first ultrasonic sensor; and determining the upstream time of flight based at least in part on an average of the upstream acoustic pulse train and the second upstream acoustic pulse train.

13 . The method of claim 9 , wherein the characteristic of the gases comprises at least one of gases concentration, flow rate, or velocity.

14 . The method of claim 9 , wherein transmitting a downstream acoustic pulse train from the first ultrasonic sensor comprises exciting the first ultrasonic sensor at a natural resonant frequency and transmitting an upstream acoustic pulse train from the second ultrasonic sensor comprises exciting the second ultrasonic sensor at the natural resonant frequency.

15 . The method of claim 9 , wherein the gases comprise oxygen and air.

16 . The method of claim 15 , wherein determining the characteristic of the gases comprises determining an oxygen concentration as a volume percentage using the equation:

OC


(

vol
.

)

=

(

100
-
20.9

)



(

G
avg

-

A
avg

)

(

O
avg

-

A
avg

)

+
20.9

where G avg represents an average of the downstream time of flight and the upstream time of flight, A avg represents an average downstream and upstream time of flight for air, and O avg represents an average downstream and upstream time of flight for oxygen.

17 . The method of claim 16 , wherein determining the characteristic of the gases comprises determining a flow rate in liters per minute for a given oxygen concentration using the equation:
F ( lpm )= k ×[( G u −G d )− f G ]

where k represents a constant factor for geometric aspects of the apparatus, G u represents the upstream time of flight, G d repr

Assignees

• Fisher & Paykel Healthcare Ltd

Inventors

• Van Schalkwyk Andre
• Newland Anthony James
• Glaves Rachael
• Liang Wenjie Robin
• Jiang-Foo Winnie Yong

Classifications

• A61M2206/14

  Static flow deviators in tubes disturbing laminar flow in tubes, e.g. archimedes screws · CPC title

• A61M2205/50

  with microprocessors or computers · CPC title

• A61M2016/1025

  the O2 concentration · CPC title

• A61M2205/3375

  Acoustical, e.g. ultrasonic, measuring means · CPC title

• A61M16/122

  with dilution · CPC title