Fluid Control Device for CPAP Using Differential Pressure Sensing
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Solution Overview
Problem
Conventional CPAP devices for treating sleep-related disorders are bulky due to the need for a larger-sized fan to compensate for pressure loss caused by flow rate sensors with straightening vanes, making them difficult to carry during travel.
Innovation Solution
A fluid control device with a suction port and exhaust port, featuring a fan unit, controller, and differential pressure sensor that eliminates the need for a flow rate sensor on the exhaust port by using a communication portion to create a differential pressure between air blowing chambers, allowing the controller to adjust fan speed based on sensed pressure differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a flow rate sensor with a straightening vane is provided in the exhaust port, then the flow rate can be measured accurately, but the pressure loss increases and the device size increases
Solution Approach 1:
The invention extracts the flow rate measurement function from the exhaust port and relocates it to the air blowing chamber. By measuring pressure differential within the chamber using a differential pressure sensor, the system eliminates the need for a flow rate sensor with straightening vane in the exhaust port, thereby reducing device size and pressure loss while maintaining measurement capability
Solution Approach 2:
The invention introduces a differential pressure sensor as an intermediary device to measure flow rate indirectly through pressure differential in the air blowing chamber. This mediator approach allows accurate flow rate measurement without requiring direct measurement in the exhaust port, avoiding the need for bulky straightening vanes
2Stress or pressure
If a larger-sized fan is used to compensate for pressure loss, then the required pressure can be maintained, but the device size increases
Solution Approach 1:
The invention extracts the pressure measurement function from the exhaust port and relocates it to the air blowing chamber. By measuring pressure differential within the chamber, the system eliminates the need for oversized fans required to compensate for exhaust port pressure loss, thereby reducing device size while maintaining required pressure
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration reduces the size and weight of the CPAP device while maintaining stable fluid flow and pressure detection, enabling efficient control of gas pressure according to the patient's respiration state without the need for a flow rate sensor, thus improving portability and performance.
Implementation Method 1
a differential pressure sensor configured to sense a differential pressure between a pressure inside the first air blowing chamber and a pressure inside the second air blowing chamber
Implementation Method 2
The communication portion causes a pressure loss in the flow of the fluid, so that a differential pressure occurs between the pressure in the first air blowing chamber and the pressure in the second air blowing chamber
Data Source
AI summary
A fluid control device includes a case including an internal space that is partitioned by a partition wall into an air blowing chamber and a control chamber. A dividing wall is disposed inside the air blowing chamber to partition an internal space of the air blowing chamber into a first air blowing chamber and a second air blowing chamber. A fan unit is housed in the second air blowing chamber. A differential pressure sensor senses a differential pressure between a pressure inside the first air blowing chamber and a pressure inside the second air blowing chamber. A controller controls a fan based on the sensed differential pressure.