Differential Pressure Sensor Sealing With Overlapping Annular Packings
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Solution Overview
Problem
Existing differential pressure sensors suffer from leakage due to unevenness on the diaphragm surface, which compromises the sealing performance and allows liquid to escape, especially in critical applications like fuel filters and urea water SCR systems.
Innovation Solution
A differential pressure detection device is designed with a diaphragm portion that includes an annular member, a strain gauge, and plates, where the annular member and strain gauge are sandwiched between the plates, and elastically deformable annular packings are used to enhance sealing by increasing the amount of elastic deformation and ensuring complete overlap with the annular member.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a metal sheet covers the upper surface of the diaphragm to protect the strain detection unit, then the strain detection unit is protected, but the O-ring cannot achieve complete sealing due to surface unevenness, causing liquid leakage
Solution Approach 1:
The sealing structure is segmented into multiple independent O-rings positioned at different locations (first O-ring at the first end, second O-ring at the bottom surface, third O-ring at the other end). This segmentation ensures that if one O-ring fails to seal completely due to surface unevenness, other O-rings can still provide sealing, thus resolving the contradiction between protecting the strain detection unit and maintaining sealing performance.
2Strength
If the O-ring abuts on the unevenness of the metal sheet, then the metal sheet provides structural support, but complete sealing is lost and liquid leakage occurs
Solution Approach 1:
Multiple O-rings are pre-positioned at different locations along the diaphragm surface before the device operates. This preliminary placement of sealing elements ensures that even if surface unevenness prevents one O-ring from sealing effectively, other O-rings are already in position to prevent liquid leakage, thus resolving the contradiction between structural support and preventing harmful factors.
3Measurement precision
If a thin film-shaped diaphragm is used to detect differential pressure, then the detection sensitivity is improved, but the surface becomes uneven when components are mounted, compromising sealing
Solution Approach 1:
The sealing approach transitions from a single-point sealing method to a multi-dimensional sealing strategy by placing O-rings at multiple locations (first end, bottom surface, other end) along the diaphragm. This dimensional expansion of the sealing system compensates for surface unevenness while preserving the thin film diaphragm's pressure detection sensitivity.
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 solution effectively prevents liquid leakage inside the differential pressure detection device by enhancing the sealing performance of the annular packings, ensuring reliable operation in applications where liquid leakage cannot be tolerated.
Implementation Method 1
The strain gauge is configured to output a signal with a magnitude according to the amount of deformation of the first plate to the detection unit
Implementation Method 2
A first elastically deformable annular packing is provided in the first groove and a second elastically deformable annular packing is provided in the second groove. The first elastically deformable annular packing abuts on the first plate and the second elastically deformable annular packing abuts on the second plate
Data Source
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AI summary
A leakage of liquid inside a differential pressure detection device is reliably preventable. A diaphragm portion that detects a differential pressure as a pressure difference between a high pressure side and a low pressure side includes an annular member, a strain gauge provided in a hollow portion of the annular member, and a first plate and a second plate provided such that the annular member and the strain gauge are sandwiched. The first plate and the second plate each abut on a first annular packing. A first groove and a second groove (the first annular packing) overlap with the annular member when viewed from a first direction along an axis of the first hole.