Aircraft Cabin Temperature Sensor Using Passive Ejector Flow
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Solution Overview
Problem
Existing air temperature sensing systems in aircraft cabins are cumbersome, adding weight and complexity, and increasing the risk of failure due to the need for dedicated ducts, fans, and control systems, which complicates maintenance and regulatory compliance.
Innovation Solution
A passive air flow system using an ejector with a restrictor to create low pressure, allowing cabin air to flow over a temperature sensor without the need for a fan, reducing weight and complexity by leveraging Bernoulli's principle to generate airflow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a temperature sensing enclosure with fan is installed to generate air flow through the duct, then reliable temperature measurement is achieved, but aircraft weight increases
Solution Approach 1:
The patent extracts the fan component from the temperature sensing system, eliminating the need for mechanical air generation while maintaining reliable temperature measurement through passive airflow integration with existing aircraft HVAC systems
Solution Approach 2:
The temperature sensing enclosure is designed to utilize the existing aircraft HVAC airflow system for multiple purposes: both for cabin air circulation and for providing the necessary airflow through the temperature sensor, thereby eliminating the dedicated fan
2Measurement precision
If a temperature sensing enclosure with fan and control systems is installed, then temperature measurement is achieved, but system complexity increases
Solution Approach 1:
The HVAC system serves dual functions: providing cabin air circulation and generating airflow through the temperature sensor, eliminating the need for separate control systems for airflow generation
Solution Approach 2:
The system uses the existing HVAC airflow to automatically provide the necessary flow through the temperature sensor without requiring additional control mechanisms, making the system self-sufficient
3Measurement precision
If a dedicated air duct with fan is installed for temperature sensing, then sufficient air flow for measurement is achieved, but aircraft weight increases
Solution Approach 1:
The existing aircraft HVAC ducting is used for dual purposes: cabin air distribution and temperature sensing airflow, eliminating the need for dedicated sensing ducts and reducing overall system weight
Solution Approach 2:
The temperature sensing airflow path is merged with the existing HVAC air distribution system, combining multiple functions into a single integrated system that reduces weight while maintaining measurement capability
4Reliability
If multiple components (enclosure, fan, wiring, control systems) are installed, then temperature sensing capability is achieved, but maintenance complexity increases
Solution Approach 1:
The fan and associated control systems are extracted from the temperature sensing system, leaving only the passive temperature sensor and enclosure that integrate with existing HVAC infrastructure, thereby simplifying maintenance
Solution Approach 2:
The HVAC system performs multiple functions including air circulation, temperature control, and temperature sensing airflow generation, reducing the number of components that require separate maintenance
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
This solution provides accurate air temperature measurements while reducing the number of components, weight, and complexity, enhancing reliability and simplifying maintenance, while adhering to regulatory standards.
Implementation Method 1
The minimal cross-sectional area of the restrictor is smaller than the first cross-sectional area of the first air duct so as to create a region of low pressure within the ejector, causing the second air flow to be suctioned over the temperature sensor and through the second air duct
Data Source
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AI summary
An air temperature sensing apparatus and a system for an aircraft includes an ejector with a first air duct (118) for receiving a first air flow (120) from an aircraft air distribution duct, the first air duct (118) defining a first cross-sectional area (134), a second air duct (122) for receiving a second air flow (124) from a passenger compartment of the aircraft, the second air flow (124) merging with the first air flow (120) downstream of the second air duct (122), and a restrictor (130) connected to the first air duct (118) defining a minimal cross-sectional area (144). The apparatus and system also include a temperature sensor (140) in fluid communication with the second air flow (124). The minimal cross-sectional area (144) of the restrictor is smaller than the first cross-sectional area (134) of the first air duct to create a region of low pressure within the ejector, causing the second air flow (124) to be suctioned over the temperature sensor (140).