Pressure Sensor Tapered Edges Freeze Protection
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Solution Overview
Problem
Pressure sensors face challenges in withstanding freeze damage due to media expansion, as existing designs lack effective protection mechanisms to divert expanding freezing media away from the sensor components.
Innovation Solution
The pressure sensor incorporates tapered and/or chamfered edges on its housing members, angled away from the substrate axis, which provide relief and direct the expanding freezing media away from the sensor, combined with a passivating agent like fluorosilicone gel to isolate electrical components and prevent corrosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pressure sensor uses a standard housing design without tapered edges, then the manufacturing process is simpler, but the sensor is vulnerable to freeze damage from expanding media
Solution Approach 1:
The housing incorporates tapered edges with specific angular geometry (e.g., 45-degree angles) that curve away from the sensor substrate. This geometric curvature redirects the path of expanding freezing media, causing it to flow along the tapered surfaces rather than directly impacting the sensor, thereby providing freeze protection through shape design
Solution Approach 2:
The housing is divided into distinct functional zones: a first housing member with tapered edges facing the media, a second housing member protecting the sensor substrate, and an intermediate chamber. This segmentation allows the outer housing to handle the mechanical impact of freezing media while isolating the sensitive sensor components, resolving the contradiction between protection and simplicity
2Reliability
If the pressure sensor housing is directly exposed to the media, then the structure is simpler, but electrical components are vulnerable to corrosion
Solution Approach 1:
A passivating agent layer is introduced as an intermediary between the freezing media and the housing/electrical components. This layer acts as a protective barrier that prevents direct contact between the corrosive media and the sensor components, thereby eliminating corrosion risk while maintaining the structural design
Solution Approach 2:
The passivating agent layer serves as a sacrificial protective element that can be easily applied and potentially replaced if needed. This disposable-like protective layer provides corrosion protection without requiring complex permanent structural modifications to the housing, resolving the contradiction between corrosion resistance and structural simplicity
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 protects the pressure sensor from freeze damage by diverting expanding media and using a passivating agent to prevent corrosion, ensuring reliable operation in freezing conditions.
Implementation Method 1
a passivating agent or coating to isolate the electrical and/or electronic components of the pressure sensor from the media while still transmitting pressure to the pressure sensor
Implementation Method 2
The one or more tapered and/or chamfered edges may help provide freeze damage protection to the pressure sensor by, for example, providing a relief so that when a freezing media expands, the freezing media is directed away from the pressure sensor
Data Source
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AI summary
A pressure sensor (10) is disclosed that can help isolate the sensor and/or sensor components from a media to be sensed and/or can help reduce sensor damage caused by harsh operating environments. In one illustrative embodiment, the pressure sensor (10) may include a substrate (12) having a pressure sensing die (18) mounted on a first side of the substrate (12), a first housing member defining a first cavity (28) around the pressure sensing die (18), and a second housing member defining a second cavity (29) on the second side of the substrate (12). A passivating agent (13), such as a gel, can be positioned in both the first cavity (28) and the second cavity (29) to transmit pressure from the media to a pressure sensing element (e.g. diaphragm) while isolating the pressure sensing element and other components from the media. In some cases, the first housing member and/or the second housing member may include an opening for exposing the passivating agent (13) to the media. In some cases, the opening (20) may be defined by one or more tapered and/or chamfered edges (21) to help provide freeze damage protection.