Buoyant Rotary Piston Water Meter Friction Reduction
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Solution Overview
Problem
Existing fluid meters face challenges in achieving high accuracy and reliability, particularly at low flow rates due to friction and noise issues, which limit their performance and manufacturing yields, and make it difficult to produce meters with high turndown ratios and thermal capabilities.
Innovation Solution
A buoyant rotary piston with a density less than 1.0g/cm3, made from materials like high impact polystyrene with glass bubbles, is used to reduce friction and noise, allowing for increased clearances and improved thermal tolerance, enabling higher accuracy and manufacturing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional dense piston is used, then the piston can maintain structural strength, but friction between the piston and chamber increases causing noise and measurement errors at low flow rates
Solution Approach 1:
The patent applies the anti-weight principle by making the piston buoyant through using materials with density less than water (such as high impact polystyrene with glass bubbles). The buoyant force counteracts the gravitational force, creating a net upward force that reduces the normal force between the piston and chamber, thereby reducing friction and improving measurement accuracy at low flow rates.
Solution Approach 2:
The patent changes the density parameter of the piston material from traditional dense materials to lightweight buoyant materials with density less than 1.0 g/cm³. This parameter change transforms the piston from a gravity-dominated component to a buoyancy-dominated component, fundamentally altering the friction characteristics and enabling accurate low flow measurement.
2Measurement precision
If tight clearances are used to improve measurement accuracy, then volumetric measurement precision improves, but manufacturing complexity and cost increase
Solution Approach 1:
By changing the density parameter of the piston to be less than the fluid density, the patent creates a buoyant force that actively compensates for clearance variations. This parameter change allows larger clearances to be used while maintaining measurement accuracy, as the buoyant piston self-adjusts its position relative to the chamber.
Solution Approach 2:
The buoyant piston provides self-adjusting functionality where the buoyant force automatically compensates for clearance variations and wear over time. The piston naturally maintains optimal positioning through the buoyant force, eliminating the need for precision manufacturing and complex adjustment mechanisms.
3Reliability
If a buoyant piston with density less than 1.0g/cm3 is used, then friction and noise are reduced improving low flow performance, but the piston material selection becomes more limited
Solution Approach 1:
The patent employs composite materials such as high impact polystyrene combined with glass bubbles to achieve the required buoyancy while maintaining mechanical strength. This composite approach allows tuning of the density to be less than water while preserving structural integrity, overcoming the limitation of material selection.
Solution Approach 2:
The patent applies local quality by incorporating glass bubbles specifically within the polystyrene matrix to reduce density, while the base polystyrene material provides the structural framework. This localized modification of material properties achieves buoyancy without sacrificing overall structural strength.
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 buoyant piston design enhances low flow performance, increases turndown ratios, improves manufacturing yields, and reduces noise, enabling the production of meters with higher specifications and increased thermal capabilities, thus addressing the limitations of existing fluid meters.
Implementation Method 1
The piston may be buoyant relative to the fluid flowing through the meter. Buoyancy of the piston may reduce friction and noise in the meter
Implementation Method 2
Figure 5 is a diagram of piston material where gravity has a downward force upon the piston material that may be countered by an upward thrust force
Data Source
Figure 1A~1D
Figure 2A
Figure 2B
AI summary
A positive displacement fluid flow meter that may have a rotary piston that rotates inside a chamber as a fluid flows through it. The rotating piston may create fixed volume discrete parcels from the passing fluid. The piston may be buoyant relative to the fluid flowing through the meter. Buoyancy of the piston may reduce friction and noise in the meter to result in a more accurate fluid flow measuring meter.