Pressure Sensor Outflow Hole Protrusion for Bubble Elimination
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Solution Overview
Problem
Conventional pressure sensors face issues with air bubbles and liquid flow rate variations due to dead volume creation and inefficient outflow designs, particularly in inline type sensors where the outflow hole positioning affects the flow rate and detection precision.
Innovation Solution
The pressure sensor design includes a protruded housing inner wall for the outflow hole, with the outflow hole center positioned closer to the pressure receiving surface than the end portion, and specific geometric relationships between radii to ensure the outflow hole overlaps the pressure receiving section, preventing air bubbles from accumulating and enhancing detection precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the outflow hole is provided at a center side of the pressure receiving surface from the end portion, then the flow rate of liquid can be controlled, but air bubbles and the like stay in the connecting portion and collectively flow out to vary the flow rate of the liquid
Solution Approach 1:
The connecting portion is designed to protrude outward before the liquid reaches it, creating a preliminary action that prevents air bubbles from entering and staying in the connecting portion. This proactive design eliminates the harmful accumulation of air bubbles before they can affect flow rate stability.
Solution Approach 2:
The protruding connecting portion creates a space that would normally be considered dead volume, but this dead volume is strategically positioned to trap and eliminate air bubbles before they enter the main flow path. The harmful air bubbles are converted into a beneficial air bubble elimination mechanism.
2Productivity
If the end portion of the pressure receiving section does not overlap the outflow hole, then the outflow efficiency of liquid is reduced, but the area of the pressure receiving section cannot be sufficiently ensured
Solution Approach 1:
The positions of the outflow hole and pressure receiving section are optimized with specific geometric relationships (conditional expressions involving r1, r2, r3, and r4) to ensure the end portion of the pressure receiving section overlaps the outflow hole. This parameter optimization simultaneously improves outflow efficiency and ensures sufficient detection area.
3Reliability
If the housing inner wall is protruded outward for the outflow hole, then air bubble accumulation is prevented, but the device complexity increases
Solution Approach 1:
The connecting portion is merged with the housing inner wall structure, forming an integrated protruding portion. This merging eliminates the need for separate air bubble elimination components, reducing device complexity while maintaining the air bubble elimination function.
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 design effectively reduces air bubble accumulation, ensures smooth liquid flow, and improves pressure detection precision by minimizing dead volume and optimizing the flow path within the sensor.
Implementation Method 1
a pressure receiving section 16 to which the pressure of the liquid is to be applied
Data Source
Figure 1
Figure 2
Figure 3(a)~3(b)
AI summary
A pressure sensor (10) is provided, which includes a pressure detector (20) that has a pressure receiving surface (15) in contact with a liquid, and detects a pressure of the liquid to a pressure receiving section (16) included in the pressure receiving surface (15), and a housing (14) having a housing inner wall (19) that demarcates a liquid chamber (11) together with the pressure receiving surface (15), wherein the housing inner wall (19) is provided with an inflow hole that causes the liquid to flow into the liquid chamber (11), and an outflow hole that causes the liquid to flow out of the liquid chamber (11), at least a part of a connecting portion, which is connected to the pressure receiving surface (15), of the housing inner wall (19) is formed as an inner wall of the outflow hole, and the housing inner wall (19) at the portion formed as the inner wall of the outflow hole protrudes more outward of the liquid chamber (11) than the other connecting portion adjacent to the portion formed as the inner wall of the outflow hole.