Differential Pressure Sensor Using Selector Valve and Single-Sided Sensor
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Solution Overview
Problem
Existing differential pressure sensors lack sensitivity and accuracy for low-flow gas flows in semiconductor fabrication, and the use of two absolute pressure sensors requires costly calibration and can produce erroneous mass flow rate outputs due to variations in operational tolerances.
Innovation Solution
A differential pressure sensor system utilizing a selector valve and a single-sided pressure sensor, coupled with a processor that generates differential pressure values from absolute pressure measurements, processes data to create best-fit curves, and discards outliers to improve accuracy and reduce calibration needs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a differential pressure sensor is used to measure low-flow gas flows, then the device complexity is reduced, but the measurement precision deteriorates due to insufficient sensitivity and accuracy
Solution Approach 1:
The patent segments the measurement function by separating the pressure sensing from the differential calculation. A single-sided pressure sensor measures absolute pressure at one location, while a selector valve segments the measurement timeline to alternately connect different pressure tap locations to the sensor, enabling differential pressure determination through temporal separation of measurements.
Solution Approach 2:
The processor acts as an intermediary that receives absolute pressure measurements from the single-sided pressure sensor at different locations via the selector valve, then calculates the differential pressure value by comparing these measurements. This intermediary computation resolves the contradiction by achieving differential measurement capability without requiring a complex differential pressure sensor.
2Measurement precision
If two absolute pressure sensors are used to determine differential pressure, then the measurement precision improves, but the device complexity and calibration requirements increase
Solution Approach 1:
The patent merges the functions of two pressure sensors into a single single-sided pressure sensor by using a selector valve to alternately connect different pressure tap locations to the same sensor. This combining approach maintains measurement precision while eliminating the complexity of matching and calibrating two separate sensors, as only one sensor requires calibration.
Solution Approach 2:
The selector valve implements periodic action by alternately switching between connecting the first pressure tap location and the second pressure tap location to the single-sided pressure sensor. This periodic switching enables the system to gather pressure data from multiple locations using a single sensor, achieving differential pressure measurement without requiring multiple simultaneously calibrated sensors.
3Measurement precision
If two absolute pressure sensors are used with tight tolerances, then the measurement precision improves, but the manufacturing precision requirements and cost increase
Solution Approach 1:
The patent combines the measurement function of two high-precision sensors into a single pressure sensor, eliminating the need for expensive sensors manufactured to tight tolerances. The single-sided pressure sensor only needs to meet standard calibration requirements, significantly reducing manufacturing precision requirements while maintaining measurement precision through the differential calculation performed by the processor.
Data Source
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AI summary
A differential pressure sensor (105) for determining a differential pressure value is provided. The differential pressure sensor (105) includes a selector valve (110) configured to receive a first pressure at a first location and a second pressure at a second location that is spaced-apart from the first location, a single-sided pressure sensor (120) coupled to the selector valve (110) and receiving either the first pressure or the second pressure, and a processing system (130) coupled to the single-sided pressure sensor (120) and configured to receive one or more first single-sided pressure measurements from the single-sided pressure sensor (120), subsequently receive one or more second single-sided pressure measurements from the single-sided pressure sensor (120), and generate the differential pressure value from the one or more first single-sided pressure measurements and the one or more second single-sided pressure measurements.