Oil Separator for Automotive Pressure Sensors
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Solution Overview
Problem
Crankcase oil vapor residues accumulate on the backside of pressure sensing element diaphragms in automotive pressure sensors, causing stress on piezoresistors and reducing sensing accuracy due to undesirable voltage shifts.
Innovation Solution
An oil separator is integrated into the pressure sensor port to elongate the fluid path and increase surface area for residue deposition, with a cover having through holes to act as a filter and mechanical stopper, preventing residue from reaching the diaphragm and improving sensing accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If oil separator is added to elongate fluid path and increase surface area, then residue deposition on diaphragm is reduced, but device complexity increases
Solution Approach 1:
The oil separator is integrated within the existing port structure of the pressure sensor housing, nesting the residue-capturing function inside the already-present fluid passage. This allows the oil separator to perform its function of trapping crankcase oil vapor residues before they reach the diaphragm, while utilizing the existing spatial envelope of the port, thereby reducing the impact on overall device complexity
Solution Approach 2:
The oil separator acts as an intermediary component between the port opening and the pressure sensing element diaphragm. It intercepts and captures oil-vapor residues in the fluid path, preventing them from depositing on the diaphragm surface. This intermediary function protects the sensing element while maintaining the integrity of the pressure measurement function
2Reliability
If oil separator is integrated into port, then residue accumulation on diaphragm is prevented, but manufacturing complexity increases
Solution Approach 1:
The oil separator is designed as a separate, modular component that can be independently manufactured and then integrated into the port structure. This segmentation allows for specialized manufacturing of the oil separator (e.g., with optimized internal geometry for residue capture) without complicating the manufacturing of the main pressure sensor housing, as the two can be produced separately and assembled
Solution Approach 2:
The port structure serves multiple functions: it provides the fluid passage for pressure measurement, houses the oil separator for residue capture, and maintains structural integrity of the sensor. By making the port multi-functional, the design avoids adding separate dedicated structures for each function, thereby reducing overall manufacturing complexity while achieving both pressure sensing and residue prevention
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 reduces residue deposition on the pressure sensing element, minimizing voltage shifts and enhancing the accuracy of pressure sensing by increasing the passage length and surface area for residue accumulation within the oil separator.
Implementation Method 1
The oil separator is configured to reduce an amount of oil-vapor residue that reaches the backside of the pressure sensing element diaphragm by elongating a path of fluid from an opening of the port to the pressure sensing element
Implementation Method 2
creating additional surface area within the port upon which oil-vapor residue may be deposited
Implementation Method 3
The cover having through holes also functions as a rough filter to reduce oil-vapor residues getting into the port
Data Source
AI summary
A pressure sensor includes a pressure sensing element in fluid communication with a port and an oil separator in the port. The oil separator is configured to reduce an amount of oil-vapor residue that reaches the pressure sensing element by elongating a path of fluid from an opening of the port to the pressure sensing element and by creating additional surface area within the port upon which oil-vapor residue may be deposited. There is also a cover, which has holes, and that is configured to prevent the oil separator from falling out of the port. The oil separator may include circular discs having cut-out portions. The cut-out portions on adjacent circular discs may be rotated relative to one another about a longitudinal axis of the oil separator. The cut-out portions may have a semi-circular shape.