Pressure Sensor Diaphragm Structure to Mitigate Zero Point Drop
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Solution Overview
Problem
Pressure sensors used in high-temperature environments experience zero point drop phenomena during evacuation after pressurized sealing, leading to unreliable output and requiring process interruptions.
Innovation Solution
A pressure sensor design featuring a diaphragm made of cobalt-nickel alloy, heat-treated at 500°C or higher, with a base ring having stress-relaxation grooves and a hermetic member, and fixed with a tightening torque of 50 N m or less, to minimize stress on the diaphragm.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a diaphragm type pressure sensor is used in high temperature environments, then the sensor can operate in vaporization supply devices, but zero point drop occurs during evacuation after pressurized sealing
Solution Approach 1:
The patent applies parameter changes by heat-treating the diaphragm at 500°C or higher to alter its material properties. This heat treatment modifies the diaphragm's stress characteristics and thermal expansion properties, enabling it to maintain stable output during evacuation after pressurized sealing in high temperature environments without experiencing zero point drop.
Solution Approach 2:
The patent implements preliminary action through pre-heating the diaphragm to high temperature (500°C or higher) before actual use. This preliminary heat treatment prepares the diaphragm's material structure in advance, eliminating internal stresses and stabilizing its properties so that when the sensor operates in high temperature environments, the diaphragm does not exhibit zero point drop during evacuation.
2Stress or pressure
If high pressure gas is applied to the pressure sensor for extended periods, then the sensor can maintain sealed state, but zero point drop occurs and recovery takes several hours
Solution Approach 1:
The patent applies parameter changes by heat-treating the diaphragm at 500°C or higher to fundamentally alter its material properties. This heat treatment modifies the diaphragm's stress-relaxation characteristics, enabling it to quickly recover from pressurized states without experiencing prolonged zero point drop, reducing recovery time from several hours to minimal levels.
3Device complexity
If the diaphragm is made of conventional material, then the sensor structure is simple, but zero point drop occurs in high temperature and pressure conditions
Solution Approach 1:
The patent applies parameter changes by heat-treating the diaphragm at 500°C or higher to fundamentally alter its material properties. This heat treatment modifies the diaphragm's stress characteristics and thermal expansion properties, enabling it to maintain stable output during evacuation after pressurized sealing in high temperature environments without experiencing zero point drop.
Solution Approach 2:
The patent implements preliminary action through pre-heating the diaphragm to high temperature (500°C or higher) before actual use. This preliminary heat treatment prepares the diaphragm's material structure in advance, eliminating internal stresses and stabilizing its properties so that when the sensor operates in high temperature environments, the diaphragm does not exhibit zero point drop during evacuation.
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 design effectively suppresses zero point drop, ensuring stable pressure measurement even in high-temperature environments, with zero point drop below 0.25% of the sealing pressure under 210°C and 200 kPa abs conditions.
Implementation Method 1
the diaphragm is configured to deform or distort in response to the pressure of the measurement gas, and the pressure of the gas is measured based on a magnitude of stress detected by the strain gauge
Implementation Method 2
the pressure of the gas is measured based on a magnitude of stress detected by the strain gauge
Implementation Method 3
a liquid raw material such as a trimethylaluminum (TMAI), a tetraethyl orthosilicate (TEOS), or a hexachlorodisilane (HCDS) is pressure fed into a vaporization chamber of the vaporization supply device and heated by a heater. The vaporized material gas is supplied to a process chamber
Implementation Method 4
a base ring having stress-relaxation grooves and a hermetic member, and fixed with a tightening torque of 50 N m or less, to minimize stress on the diaphragm
Data Source
AI summary
The pressure sensor 10 comprises: a bottomed cylindrical sensor module 11 having inside a pressure receiving chamber C1 communicating with a flow path and including a diaphragm 11a in contact with the pressure receiving chamber; a pressure detecting element 12 for outputting a strain of the diaphragm 11a as a pressure; a base ring 14 fixed at an outer edge of an open-side end part 11c of the sensor module and disposed on an outer peripheral side of the sensor module 11; a hermetic member 13 fixed to the base ring 14 for forming a sealed vacuum chamber C2 opposite to the pressure receiving chamber C1 across the diaphragm 11a; a gasket 18 sandwiched between the base ring 14 and a body 5; and a pressing flange 19 for pressing the base ring 14 to the body 5 through the gasket 18.