Air Flow Sensor Housing Prevents Temperature Probe Damage
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Solution Overview
Problem
Conventional air flow measuring devices with bypass flow passages often damage temperature sensors due to contact with the duct during insertion, and protection members increase pressure loss by projecting outward into the mainstream.
Innovation Solution
The air flow measuring device is designed with a housing and fitted part that includes a bypass flow passage with a flow sensor and temperature sensor component, where the positional relationship of the housing and temperature sensor components prevents contact with the duct during insertion, eliminating the need for protection members and reducing pressure loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a protection member is provided around the temperature sensor component to prevent contact with the duct during insertion, then the temperature sensor is protected from damage, but the protection member projects outward into the mainstream passage and increases pressure loss
Solution Approach 1:
The patent repositions the temperature sensor component from a location that requires external protection members to a position where the housing structure itself provides protection. By locating the temperature sensor within the housing and positioning the housing ends to contact the duct inner peripheral surface, the design eliminates the need for protruding protection members while maintaining sensor protection during insertion.
Solution Approach 2:
The patent integrates the temperature sensor protection function into the housing structure itself. The housing serves dual purposes: it contains the temperature sensor component and simultaneously provides the protective barrier during insertion by having its ends contact the duct inner peripheral surface. This merging eliminates separate protection members that would increase pressure loss.
2Measurement precision
If the temperature sensor component is positioned close to the duct wall for accurate temperature measurement, then measurement accuracy improves, but the sensor becomes vulnerable to damage during insertion
Solution Approach 1:
The patent places the temperature sensor component inside the housing, which is then inserted into the duct. The housing acts as a protective container that shields the temperature sensor during insertion while allowing the sensor to be positioned appropriately for temperature measurement. The nested structure enables both protection and measurement functionality.
Solution Approach 2:
The housing serves as an intermediary structure between the temperature sensor and the duct environment. It provides mechanical protection during insertion while allowing the temperature sensor to function in proximity to the airflow for accurate temperature measurement without direct exposure to damage risks.
3Reliability
If protection members are added around the temperature sensor, then sensor damage is prevented, but the device complexity increases
Solution Approach 1:
The patent combines the housing structure with the protection function, eliminating the need for separate protection members. The housing serves both as the mounting structure for the temperature sensor and as the protective element during insertion, thereby reducing overall device complexity while maintaining sensor protection.
Solution Approach 2:
The housing is designed to perform multiple functions: containing the temperature sensor component, providing structural support, and serving as the protective barrier during insertion by contacting the duct inner peripheral surface. This multi-functionality eliminates the need for additional dedicated protection members, simplifying the overall device structure.
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 configuration prevents damage to the temperature sensor and minimizes pressure loss by ensuring the temperature sensor does not come into contact with the duct, thereby reducing the need for protection members and maintaining airflow efficiency.
Implementation Method 1
a flow sensor disposed in the bypass flow passage and configured to measure a flow rate of air
Implementation Method 2
a temperature detecting element connected to the terminal and configured to detect temperature of air flowing in the duct outside the housing
Data Source
AI summary
An air flow measuring device includes a fitted part, a housing, a flow sensor, and a temperature sensor component. A projection shape of the fitted part onto an imaginary plane is a first circle. On the imaginary plane, a first point and a second point are located on the first circle or inward of the first circle, and a third point is located inward of the first circle. A diameter of an imaginary circle passing through the first, second, and third points is larger than a diameter of the first circle. The first, second, and third points have such a positional relationship that, when at least one of the first and second points comes into contact with an inner peripheral surface of an attachment hole at time of insertion of the housing into a duct, the third point is away from the inner peripheral surface of the attachment hole.