Vortex Flowmeter Piezoelectric Case Hollow Structure Low Flow Accuracy
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Solution Overview
Problem
Conventional vortex flowmeters face challenges in accurately measuring low flow rates due to a short pressure receiving part, which may not vibrate in response to Karman vortices, and elongating this part increases the device's size.
Innovation Solution
The design includes a piezoelectric element case with a hollow portion and ribs, allowing the pressure receiving part to vibrate effectively at low flow rates without increasing the device's size, enhancing sensitivity and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the pressure receiving part is elongated to enhance vibration response to Karman vortices, then the sensitivity of the piezoelectric element is improved, but the length of the flow rate measuring unit increases resulting in larger device size
Solution Approach 1:
The patent introduces a hollow portion that extends in the radial direction (thickness direction) of the pressure receiving part, rather than only elongating it in the axial direction. This dimensional change allows the pressure receiving part to achieve enhanced vibration response and sensitivity without increasing the axial length of the flow rate measuring unit, thus resolving the contradiction between measurement precision and device size.
Solution Approach 2:
The patent changes the structural parameters of the pressure receiving part by introducing a hollow portion with specific thickness and depth ratios. This parameter modification optimizes the vibration characteristics of the pressure receiving part, enabling it to respond effectively to Karman vortices at low flow rates while maintaining a compact axial length, thereby improving measurement accuracy without increasing device size.
2Reliability
If the pressure receiving part is made longer to detect low flow rates, then the sensitivity is enhanced, but the device complexity and size increase
Solution Approach 1:
Instead of extending the pressure receiving part in the axial direction, the patent utilizes the radial dimension by introducing a hollow portion. This approach enhances the vibration response and detection capability at low flow rates while avoiding the increased structural complexity and size that would result from axial elongation, thus resolving the contradiction between reliability and device complexity.
Solution Approach 2:
The hollow portion creates a thin-walled structure in the pressure receiving part that is highly sensitive to vibration from Karman vortices. This thin-walled design enhances detection capability at low flow rates while maintaining structural integrity and avoiding excessive complexity, as the hollow structure naturally provides the necessary flexibility for vibration response.
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 enables accurate flow rate measurement at low flow rates while maintaining a compact device size by ensuring the pressure receiving part vibrates in response to Karman vortices, improving sensitivity and preventing resonance.
Implementation Method 1
the piezoelectric element that receives the vibration (the deformation) outputs a voltage signal
Implementation Method 2
a flow rate measuring unit placed downstream of the vortex generator and configured to detect a Karman vortex generated by the vortex generator
Data Source
Figure 1
Figure 2
Figure 3~5
AI summary
In this vortex flowmeter (1) provided with a vortex generator (16) and a flow rate measurement unit (30), the flow rate measurement unit (30) comprises a piezoelectric element (32) and a piezoelectric element case (31), wherein the piezoelectric element case (31) comprises: a fitted part (312) which is fitted in the main body case (2); a pressure receiving unit (314) which protrudes from the distal end surface (312a) of the fitted part (312) and which is arranged in a main body flow path (23); a space (319) which is formed along the axial direction of the piezoelectric element case (31) in the fitted part (312) and which separates the fitted part (312) and the pressure receiving unit (314); and a slit (318) which is formed inside of the pressure receiving unit (314) and which houses the piezoelectric element (32).