Gas Backpressure Sensor Assembly with Biasing Apparatus
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Solution Overview
Problem
Current pressure sensor technologies for high-pressure exhaust gas recirculation systems are either too bulky and expensive (ceramic capacitive technology) or prone to adhesive bond failure due to high exhaust gas backpressure and pulsations (silicon piezoresistive technology).
Innovation Solution
A compact and cost-effective pressure sensor assembly featuring a housing with a diaphragm-based micromachined silicon chip and a biasing apparatus, such as an elastomeric bumper or spring, to oppose gas pressure and reduce stress on adhesives, ensuring reliable long-term operation under high pressures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If ceramic capacitive technology is used for pressure sensing, then measurement accuracy is improved, but packaging size increases and cost increases
Solution Approach 1:
The patent extracts the sensing function from a bulky ceramic capacitive sensor and implements it using a miniaturized silicon piezoresistive chip with a small diaphragm, eliminating the need for large ceramic components while maintaining pressure measurement capability
Solution Approach 2:
The patent uses a silicon-based piezoresistive sensing mechanism that replicates the pressure sensing function of ceramic capacitive sensors but with significantly reduced size and cost, achieving comparable measurement accuracy through different physical implementation
2Volume of moving object
If silicon piezoresistive technology is used for pressure sensing, then packaging size is reduced and cost is reduced, but adhesive bond reliability deteriorates under high pressure and temperature
Solution Approach 1:
The patent incorporates a compliant mounting structure that anticipates and cushions the thermal and pressure-induced expansion forces before they can damage the adhesive bonds, preventing fatigue failure through pre-designed stress accommodation
Solution Approach 2:
The patent changes the mechanical parameters of the mounting structure to be more compliant and flexible, allowing the silicon chip to expand and move with thermal and pressure changes without creating damaging stress concentrations at the adhesive joints
3Ease of manufacture
If silicon piezoresistive technology is used for pressure sensing, then manufacturing cost is reduced, but adhesive bond reliability deteriorates under high temperature and pressure pulsations
Solution Approach 1:
The compliant mounting structure is designed in advance to absorb and accommodate thermal expansion and pressure pulsation forces, preventing adhesive bond failure before it occurs during operation under harsh conditions
Solution Approach 2:
The patent employs a composite mounting structure combining rigid and compliant materials that work together to provide both structural support and stress accommodation, maintaining adhesive bond reliability under high temperature and pressure conditions while keeping manufacturing costs low
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 provides a small, low-cost pressure sensor capable of withstanding high exhaust gas pressures while minimizing adhesive fatigue, suitable for automotive, industrial, and aerospace applications.
Implementation Method 1
silicon piezoresistive Wheatstone bridge pressure sensing technology
Implementation Method 2
biasing apparatus, such as an elastomeric bumper or spring
Data Source
AI summary
A gas sensor assembly for sensing a pressure of a gas including a housing, a carrier, an electronic chip, a cap and a biasing apparatus. The housing has a wall defining cavity with a port open to the gas. The carrier is mounted to the wall in the cavity. The electronic chip is secured to the carrier on an opposed side from the port and includes a diaphragm portion exposed to the port. The cap is mounted to the chip on an opposed side from the carrier. The biasing apparatus is located between the cap and the wall of the housing, with the biasing apparatus being configured to bias the cap toward the chip whereby gas pressure acting against the diaphragm is opposed by the biasing apparatus.