Spirometer Turbine Curved Flow Director Blades

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Solution Overview

Problem

Conventional turbine spirometers face challenges in measuring low flow rates due to static discharge and 'dead band' effects, which cause the vane to stop spinning prematurely, failing to meet the minimum detectable flow requirements set by the ATS/ERS standards.

Innovation Solution

The spirometer turbine assembly features curved flow director blades that minimize static electricity buildup and eliminate 'dead bands' by ensuring continuous overlap of blade edges, with the option of incorporating anti-static materials to maintain vane spinning at low flow rates, and is oriented vertically to reduce drag.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional turbine spirometers use straight flow director blades with spaces between them, then the device structure is simple and easy to manufacture, but static electricity builds up on the vane edges causing the vane to stop spinning at low flow rates

Engineering Contradiction:

Improvelow flow rate measurement capabilityVSAvoidflow director blade design

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The flow director blades are designed with curved leading edges that sweep through the vane edges in a circular path, eliminating straight edges that align with the vane. This curvature prevents static electricity buildup by ensuring continuous contact between the blade edges and vane surface, allowing the vane to spin freely even at low flow rates down to 0.015 L/s.

Inventive Principle:

Principle #14Spheroidality (Curvature)

Solution Approach 2:

The flow director is divided into multiple blades (typically 3-5) arranged radially around the vane. Each blade is independently shaped with curved leading edges, and the blades are positioned to ensure continuous coverage of the vane perimeter. This segmentation allows the curved edge design to be applied effectively across the entire flow director structure.

Inventive Principle:

Principle #1Segmentation

2Reliability

If spaces are left between flow director blades for structural reasons, then manufacturing is easier, but dead bands are created where air flows linearly without engaging the blades

Engineering Contradiction:

Improvecontinuous air flow engagementVSAvoidflow director assembly

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The curved leading edges of the flow director blades sweep through the vane edges in a circular path, ensuring that air flow is continuously redirected at an angle across the entire vane perimeter. This curved geometry eliminates dead bands by maintaining continuous engagement between the airflow and the blades, even when spaces exist between adjacent blades for manufacturing purposes.

Inventive Principle:

Principle #14Spheroidality (Curvature)

3Measurement precision

If the vane is designed to spin freely with minimal friction, then low flow rates can be detected, but static electricity causes the vane to lock up and stop spinning

Engineering Contradiction:

Improveminimum detectable flow rateVSAvoidstatic electricity discharge

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

Instead of trying to eliminate static electricity entirely, the curved blade design utilizes the static charge buildup as a beneficial adhesive force. The curved leading edges ensure continuous contact with the vane surface, allowing static electricity to create a slight adhesive effect that maintains engagement between the blades and vane, preventing lockup while still enabling detection of very low flow rates down to 0.015 L/s.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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

The solution enables the spirometer to effectively measure flow rates as low as 0.015 L/s, ensuring accurate data collection and preventing static lockup and 'dead band' issues, thus meeting the ATS/ERS standards for spirometry.

Implementation Method 1

the static discharge caused by the edge alignment between the inside edge of flow director blades and the outside edge of the vane

Methodology Applied

Scientific EffectStatic electricity: Electrostatics

Implementation Method 2

causes exhaled air to swirl, twisting the air into a vortex. The angular velocity of the vortex is proportional to the flow rate of air passing through the mouth piece

Methodology Applied

Scientific EffectVortex flow: Vortex Ring

Implementation Method 3

A light source, such as an infrared transmitter, transmits a continuous infrared beam that is interrupted by the vane as it rotates, resulting in infrared pulses

Methodology Applied

Scientific EffectOptical interruption:

Data Source

PatentUS11672441B2Low flow spirometer turbine

Publication Date: 2023.06.13 MONITORED THERAPEUTICS INC

AI summary

A spirometer turbine assembly is described, having a housing with a proximal end opening, a distal end opening and an airflow channel therebetween. A first flow director has a first plurality of flow director blades with distal edges that curve in a plane perpendicular to a longitudinal axis of the airflow channel, and a vane is connected to an axel positioned distal to the first flow director. A spirometer turbine assembly having an anti-static material is also described.