Pressure Sensor Plugs for Cold Weather Volume Expansion
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Solution Overview
Problem
Aqueous urea solutions used in selective catalytic reduction systems can freeze at temperatures around -11 °C, causing volume expansion that damages pressure sensor components due to increased contact force.
Innovation Solution
A pressure sensor design with a compensating structure, including a plug with a through-hole and hollow chambers, that can deform to accommodate volume expansion, and a cavity with a higher surface area to volume ratio to control freezing sequence, preventing component damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a pressure sensor is used to measure liquid pressure, then pressure measurement function is achieved, but the sensing element is damaged when the liquid freezes and expands
Solution Approach 1:
The patent introduces a compressible element (such as a foam plug or elastomeric material) into the pressure sensor housing before the liquid freezes. This element acts as a cushion that can be compressed to accommodate the volume expansion of freezing liquid, thereby preventing damage to the sensing element while maintaining pressure measurement functionality
Solution Approach 2:
The patent changes the physical state of the compensating structure by using a compressible element that can change its volume in response to temperature changes. When the liquid freezes and expands, the compressible element compresses to absorb the expansion, and when the liquid thaws, the element returns to its original state
2Reliability
If a compressible element is added to compensate for volume expansion, then component protection is improved, but device complexity increases
Solution Approach 1:
The patent uses a foam plug or porous compressible material that can be easily inserted into the pressure sensor housing. The porous structure of the foam allows it to compress and expand efficiently, providing protection against freezing damage while adding minimal structural complexity to the device
Solution Approach 2:
The compressible element is designed as a simple, inexpensive component that can be easily replaced if needed. Using a foam plug or similar simple material keeps the additional complexity low while effectively solving the freezing protection problem
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
Effectively compensates for volume expansion due to freezing, preventing damage to pressure sensor components even under enclosed freezing conditions, and allows for flexible application across different temperatures and mediums.
Implementation Method 1
the liquid passed into the pressure sensor may be frozen due to such as a low temperature and converted into solid phase, which will cause a volume expansion
Implementation Method 2
a compressible element for overpressure protection is arranged inside the chamber
Data Source
Figure 1A~1B
Figure 1C~1D
Figure 2A~2C
AI summary
A pressure sensor (1) including a housing (100) with a sensing element (200) therein. A communication passageway (127) is formed in the housing (100). The sensing element (200) is in fluid communication with an outside of the housing (100) through the communication passageway (127). The pressure sensor (1) is further provided with a compensating structure (250), so that when a contact force is increased due to occurrence of a volume expansion of a liquid passed into the housing (100) through the communication passageway, the compensating structure (250) is used to compensate the volume expansion. A plug (300) may also be used with the pressure sensor (1). The pressure sensor (1) is such that when the liquid within the pressure sensor has an increased volume due to being frozen, such increased volume can be compensated, so as to prevent the components of the pressure sensor (1) from being damaged.