Sanitary Pressure Sensor Zero Point Stability
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Solution Overview
Problem
Sanitary pressure sensors face challenges in maintaining sensor sensitivity due to the need for high corrosive resistance and cleanness, which often results in diaphragm deformation during pipe connection, causing variations in zero point shifts in sensor output.
Innovation Solution
A pressure sensor design featuring a diaphragm with orthogonal structural bodies supporting a semiconductor chip, where resistors are strategically positioned to minimize zero point shifts by aligning stress directions, ensuring consistent sensor output regardless of clamp tightening position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the film thickness of the diaphragm is increased to make it difficult to break, then the diaphragm strength is improved, but the sensor sensitivity is reduced because the amount of deformation becomes minute
Solution Approach 1:
The patent applies local quality by creating a thin-walled portion (local thinning) in the semiconductor chip at the position where stress should be concentrated. This allows the diaphragm to maintain high overall strength while creating a localized region with high sensitivity to deformation, enabling accurate detection of pressure changes without requiring the entire diaphragm to be thin.
Solution Approach 2:
The patent transitions from considering only the thickness dimension to incorporating the planar distribution dimension by strategically positioning the thin-walled portion and resistors. This dimensional approach allows optimization of both strength and sensitivity by controlling where material is removed in the planar view, not just the thickness direction.
2Ease of operation
If a clamp is used to connect the pipe to the sanitary pressure sensor, then the connection is established, but the diaphragm is deformed causing variations in zero point shifts
Solution Approach 1:
The patent introduces the thin-walled portion as an intermediary element that absorbs and distributes the stress caused by clamp tightening. This intermediate structure protects the main diaphragm from direct deformation by providing a compliant zone that accommodates mounting stresses, thereby maintaining zero point stability during connection operations.
Solution Approach 2:
The patent converts the harmful effect of clamp-induced stress into a beneficial outcome by strategically positioning the thin-walled portion to absorb these stresses. The stress that would normally deform the diaphragm and cause zero point shifts is instead directed into the thin-walled region, where it does not affect the measurement accuracy of the main diaphragm area.
3Measurement precision
If the resistors are positioned to maximize sensitivity, then the sensor sensitivity is improved, but the zero point shifts vary depending on clamp tightening position
Solution Approach 1:
The patent applies asymmetry by creating an asymmetric stress distribution pattern through the thin-walled portion design. The resistors are positioned to exploit this asymmetric stress field, where the thin-walled region creates a concentrated stress zone that consistently affects all resistors in a predictable manner, maintaining zero point stability despite variations in clamp tightening position.
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 variations in sensor output zero points and enhances sensitivity by evenly distributing stress across the resistors, improving the accuracy and reliability of pressure measurements.
Implementation Method 1
detecting changes in the resistance value of the diffusion resistors caused by the piezoresistive effect based on distortion of the semiconductor chip
Data Source
AI summary
A pressure sensor includes a diaphragm having a first principal surface and a second principal surface, a semiconductor chip in which resistors constituting a strain gauge are formed, a first structural body having one end coupled to a center of a second principal surface of the diaphragm and the other end coupled to the other surface of the semiconductor chip, and at least two second structural bodies disposed in two straight lines, orthogonal to each other, that pass through the center of the diaphragm in plan view so as to be disposed separately from the first structural body, and having one ends coupled to the second principal surface and the other ends coupled to the other surface of the semiconductor chip, in which the resistors are formed in regions between the first structural body and the second structural bodies in plan view in the semiconductor chip.