Flow Velocity Sensor Weatherability via Back-Surface Resistor Mounting
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing flow velocity sensors are prone to deterioration and breakage due to moisture, dirt, and contaminants in the fluid, leading to inferior weatherability.
Innovation Solution
A flow velocity sensor design featuring a film-shaped substrate with a thickness of 0.08 mm to 1.0 mm, where the heat generating and temperature compensating resistors are mounted on the opposite side of the substrate from the fluid, covered by an insulating resin film and a metal film, with holes for heat dissipation, and a cover member to enhance weatherability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the heat generating resistor and temperature compensating resistor are arranged close to each other on the surface of the insulating substrate, then the device complexity is reduced, but the weatherability deteriorates due to frequent contact with fluid causing deterioration and breakage
Solution Approach 1:
The patent moves the resistors from the front surface (first surface) to the back surface (second surface) of the substrate, utilizing the third dimension (depth/thickness) to separate the resistors from the fluid contact zone. This spatial repositioning allows the resistors to be protected from fluid while maintaining close proximity for thermal coupling, thus improving weatherability without increasing device complexity.
Solution Approach 2:
The substrate acts as an intermediary medium between the fluid and the resistors. By positioning the heat generating resistor and temperature compensating resistor on the second surface of the substrate, the substrate itself becomes the mediator that allows thermal interaction while preventing direct fluid contact with the resistors, thereby improving their weatherability and reliability.
2Temperature
If the resistors are mounted on the first substrate surface exposed to fluid, then the heat transfer efficiency is improved, but the weatherability deteriorates due to moisture and contaminant contact
Solution Approach 1:
The patent utilizes the thickness dimension of the substrate to reposition the resistors on the second surface, away from the fluid-exposed first surface. This dimensional change allows the resistors to remain thermally coupled to the fluid through the substrate while being physically protected from direct fluid contact, thus maintaining heat transfer efficiency while improving weatherability.
Solution Approach 2:
The substrate itself acts as a thin film or shell that covers and protects the resistors from the fluid environment. By mounting the resistors on the second surface of this protective substrate film, the resistors are shielded from moisture and contaminants while the substrate's thin nature allows efficient thermal conduction from the fluid to the resistors.
3Measurement precision
If the heat generating resistor is heat-controlled to have higher temperature than fluid, then the flow velocity detection sensitivity is improved, but the risk of deterioration from moisture and contaminants increases
Solution Approach 1:
The substrate serves as an intermediary barrier that allows the heat generating resistor to maintain elevated temperature for sensitive flow velocity detection while preventing direct contact between the hot resistor and the fluid containing moisture and contaminants. This mediator approach enables high measurement precision while protecting against deterioration.
Solution Approach 2:
By positioning the heat generating resistor on the second surface of the substrate, the patent creates a spatial separation in the third dimension between the high-temperature resistor and the fluid. This allows the resistor to operate at elevated temperatures for improved detection sensitivity while being physically protected from fluid-related deterioration mechanisms.
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 design significantly improves the weatherability of the flow velocity sensor by protecting the resistors from direct fluid contact, maintaining sensitivity and functionality even if the holes are blocked, while ensuring efficient heat transfer and reducing directivity errors.
Implementation Method 1
a flow velocity sensor detects a flow velocity of fluid by utilizing heat dissipation of a heating element. The heat dissipation of the heating element corresponds to the flow velocity of the fluid.
Implementation Method 2
a heat generating resistor (heating element)... The heat generating portion of the resistor faces the first area
Implementation Method 3
an insulating film. The insulating film covers a part or an entirety of each of the first and second substrate surfaces. The insulating film is configured with a resin film and/or a glass film.
Implementation Method 4
a metal film or a vapor deposition metal film that covers the insulating film
Data Source
AI summary
A flow velocity sensor includes a substrate, a resistor, and a signal processing section. The substrate has first and second substrate surfaces outwardly opposite to each other. The first substrate surface is exposed to a fluid. The resistor is mounted on the second substrate surface. The resistor has a heat generating portion facing the second substrate surface. The signal processing section is configured to receive a signal from the resister. The signal from the resistor represents heat dissipation of the resistor. A fluid velocity is detected based on the signal from the resistor.