Multi-hole Orifice Plate for Precision Flow Control
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Solution Overview
Problem
Conventional orifice plates for flow control experience a reduction in the control range of the pressure ratio P2/P1 at which critical expansion conditions are established with an increase in orifice diameter, leading to decreased flow control accuracy and a larger lower limit of the control range, especially in semiconductor manufacturing systems.
Innovation Solution
A multi-hole orifice plate is designed where the opening area of one orifice is divided into multiple smaller orifices, maintaining a constant pressure ratio P2/P1 at which critical expansion conditions are established, even with increased flow rates, and can be produced at a lower cost through pressing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the orifice diameter is increased to handle higher flow rates, then the flow capacity is improved, but the control range of the pressure ratio P2/P1 at which critical expansion conditions are established is reduced
Solution Approach 1:
The patent divides a single large orifice into multiple smaller orifices arranged in an array. This segmentation allows the system to maintain the total flow capacity equivalent to a large orifice while each individual small orifice maintains the critical expansion characteristics. The multiple orifices collectively provide the required flow capacity without sacrificing the pressure ratio control range, as each small orifice operates within its optimal critical expansion regime.
Solution Approach 2:
The patent changes the geometric parameters of the orifice system by transitioning from a single large diameter orifice to multiple small diameter orifices. This parameter change maintains the total open area for equivalent flow capacity while fundamentally altering the flow characteristics to preserve critical expansion conditions across a wider pressure ratio range.
2Productivity
If a single large orifice is used to increase flow rate, then the productivity is improved, but the manufacturing precision and control accuracy are reduced
Solution Approach 1:
By segmenting the orifice into multiple smaller openings, each small orifice can be manufactured with higher precision using standard pressing techniques. The cumulative effect of multiple precisely-manufactured small orifices achieves both high flow capacity and high flow control accuracy, overcoming the limitation of single large orifice manufacturing variability.
3Adaptability or versatility
If multiple small orifices are used to maintain critical expansion conditions, then the adaptability is improved, but the device complexity increases
Solution Approach 1:
The patent merges multiple small orifices into a single integrated orifice plate structure. This combining approach maintains the advantages of multiple orifices (wide pressure ratio control range) while simplifying the overall device structure to a single plate component, avoiding the complexity of multiple separate components or complex assembly requirements.
Solution Approach 2:
The patent utilizes parameter changes in the orifice configuration (number, size, and arrangement of orifices) to achieve the desired adaptability. By optimizing these parameters, the system attains wide pressure ratio control range while keeping the structural complexity manageable through a simple plate design.
4Manufacturing precision
If complex orifice formation methods are used to achieve precise flow control, then the manufacturing precision is improved, but the ease of manufacture deteriorates
Solution Approach 1:
The patent employs a simple pressed orifice plate design that can be manufactured using inexpensive pressing processes. This approach replaces costly and complex manufacturing methods (such as precision drilling, electric discharge machining, or etching) with a simpler, more cost-effective pressing technique that achieves sufficient precision for the application.
Solution Approach 2:
The patent changes the manufacturing approach by using pressing to form the orifices directly in the plate material. This parameter change in the manufacturing process achieves acceptable dimensional accuracy for flow control applications while dramatically reducing production cost and complexity compared to precision machining methods.
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 maintains a constant pressure ratio P2/P1, preventing reduction in the control range and enhancing flow control precision, while reducing production costs by allowing easy formation of multiple orifices through pressing.
Implementation Method 1
When the pressure ratio P2/P1 between the pressure P1 upstream of the orifice and the pressure P2 downstream of the orifice is equal to or lower than the pressure ratio at which the critical expansion conditions of a gas are established, the orifice-passing gas flows at the speed of sound
Data Source
AI summary
A multi-hole orifice plate for flow control includes an orifice plate for controlling the flow rate of a fluid, wherein the opening area of one orifice necessary for the passage of a predetermined flow rate of fluid is divided to provide a plurality of orifices having a total opening area equal to said opening area.