Coaxial Pressure-Based Mass Flow Control for Faster Bleeding
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Solution Overview
Problem
Traditional pressure-based mass flow controllers (PBMFCs) suffer from high dead volume, leading to prolonged bleeding times and increased manufacturing complexity and cost, especially in low flow applications where the conductance of the flow nozzle is small.
Innovation Solution
The improved mass flow controller design features a pressure drop element, such as a flow nozzle, disposed coaxially with the outlet orifice of the adjustable valve within the same bore, reducing dead volume and simplifying manufacturing by eliminating the need for additional machining steps, with upstream and downstream pressure sensors used to determine flow rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If traditional PBMFC design with separate pressure drop element and valve is used, then flow control function is achieved, but dead volume is high leading to prolonged bleeding time
Solution Approach 1:
The pressure drop element and valve are merged into a single integrated component where the pressure drop element is disposed within the valve bore, eliminating the need for separate components and reducing dead volume between them
Solution Approach 2:
The pressure drop element is nested within the valve bore structure, with the pressure drop element disposed coaxially within the bore of the valve, placing one component inside the structural space of another to minimize overall volume
2Ease of manufacture
If traditional PBMFC design with multiple separate components is used, then flow control function is achieved, but manufacturing complexity and cost increase
Solution Approach 1:
The pressure drop element and valve are combined into a single manufacturable unit with fewer assembly steps, where the pressure drop element is integrated within the valve body structure rather than being a separate assembled component
Solution Approach 2:
The integrated component serves multiple functions simultaneously - the valve provides flow control while the embedded pressure drop element provides flow restriction and measurement reference, eliminating the need for separate dedicated components for each 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 configuration significantly reduces bleeding time and manufacturing complexity and cost by minimizing dead volume and streamlining the assembly process, achieving faster valve closure and more efficient gas delivery with reduced residual gas bleeding.
Implementation Method 1
A pressure drop element is disposed coaxially with the valve element within the bore
Implementation Method 2
An upstream pressure sensor is configured to detect a pressure at a location in the flow path between the adjustable valve and the pressure drop element, and a controller is configured to determine a flow rate through the flow path based on pressure as detected by the upstream pressure sensor
Data Source
AI summary
Mass flow controllers that can provide for improved bleeding time and can be manufactured with less complexity and cost are provided. A mass flow controller includes a body having a valve outlet bore defining a flow path and an adjustable valve configured to control flow of a gas through the flow path. A valve element includes an outlet orifice of the adjustable valve and is disposed within the bore. The mass flow controller further includes a pressure drop element disposed coaxially with the valve element within the bore. An upstream pressure sensor is configured to detect a pressure at a location in the flow path between the adjustable valve and the pressure drop element, and a controller is configured to determine a flow rate through the flow path based on pressure as detected by the upstream pressure sensor.