Sphygmomanometer Valve Structure for Blocking Cuff Fiber Intrusion
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Solution Overview
Problem
Conventional fluid controllers in sphygmomanometers are prone to malfunctions due to foreign matter, such as fibers from the cuff, which can block valves or reduce air flow rates, leading to issues during air charging and discharging.
Innovation Solution
A valve design with a first flow passage connecting the second and third air holes, featuring a narrow portion with a protruded portion and a diaphragm, where the shortest distance between them is less than the third air hole's diameter, preventing foreign matter from passing through and ensuring proper air flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional valve design with direct connection between air holes is used, then air flow rate is maintained, but foreign matter can block the valve or reduce air flow rates
Solution Approach 1:
The valve housing is segmented into multiple chambers (first valve chamber and second valve chamber) separated by a diaphragm. This segmentation prevents foreign matter from one chamber from affecting the valve operation in another chamber, thereby improving reliability without significantly increasing overall structural complexity.
Solution Approach 2:
A diaphragm is introduced as an intermediary element between the first and second valve chambers. The diaphragm allows pressure transmission while physically blocking foreign matter from passing between chambers, resolving the contradiction between maintaining air flow and preventing foreign matter intrusion.
2Object-affected harmful factors
If the third air hole is made larger to prevent foreign matter blocking, then foreign matter passage is improved, but air sealing performance deteriorates
Solution Approach 1:
The valve structure is divided into separate chambers with the diaphragm acting as a barrier. This allows the third air hole to be optimized for air sealing in the second valve chamber while foreign matter is prevented from reaching critical areas by the diaphragm segmentation.
Solution Approach 2:
The diaphragm serves as an intermediary that blocks foreign matter while allowing air pressure to pass through. This enables the third air hole to maintain proper sealing dimensions without being vulnerable to foreign matter blocking, as the diaphragm prevents such matter from reaching the air hole.
3Object-affected harmful factors
If a narrow portion is added to the flow passage to block foreign matter, then foreign matter blocking is prevented, but flow passage resistance increases
Solution Approach 1:
The flow passage is segmented into multiple routes by the diaphragm. Foreign matter is blocked at the segmentation point (diaphragm) rather than by narrowing the entire passage, preventing foreign matter intrusion while maintaining low flow resistance through alternative paths.
Solution Approach 2:
The diaphragm acts as an intermediary barrier that blocks foreign matter without requiring narrowing of the main air flow passages. Air flow maintains low resistance by passing through the designed flow passages, while the diaphragm intercepts foreign matter before it can cause blocking.
Data Source
AI summary
A fluid controller includes a piezoelectric pump, a valve, and a cuff. The valve includes a first valve housing, a diaphragm, and a second valve housing. The second valve housing has a second air hole, a third air hole, and a first valve seat. The second air hole connects to the internal space of the cuff. The third air hole connects to the outside of the fluid controller. The first valve seat is formed around the third air hole. Together, the second valve housing and the diaphragm form a first flow passage. The first flow passage connects the second air hole and the third air hole to each other. The second valve housing has a protruded portion protruding toward the diaphragm and providing a portion of the first flow passage. The shortest distance between the protruded portion and the diaphragm is less than the diameter of the third air hole.