Vehicular Indoor Temperature Sensor Venting for Fast Response
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Solution Overview
Problem
Non-air-breathing vehicular indoor temperature sensors face delayed response times due to isolation from outdoor air, leading to reduced sensitivity and difficulty in immediate temperature control, and are susceptible to moisture ingress that can damage PCB components.
Innovation Solution
A vehicular indoor temperature sensor design with a cut portion in the sensor housing to discharge foreign substances and increase air contact area, featuring a cylindrical tip sensor unit with a cut portion and protrusions to enhance air flow, and a conformal coating on the PCB substrate to protect against moisture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the sensor housing is tightly sealed to protect PCB components from foreign substances, then reliability is improved, but the response time of temperature sensors is delayed
Solution Approach 1:
The housing is segmented into multiple sections with a specifically designed cut portion that separates the protective function from the sensing function. The cut portion is positioned to allow air flow to the temperature sensors while the overall housing structure maintains protection for PCB components.
Solution Approach 2:
The housing structure has different properties in different locations: the majority of the housing provides tight sealing for protection, while the cut portion provides open access for temperature sensing. This local differentiation allows simultaneous achievement of protection and fast response.
2Reliability
If the tip sensor unit is fully enclosed to protect from moisture, then reliability is improved, but the air contact area is reduced and sensitivity decreases
Solution Approach 1:
The tip sensor unit housing is divided into enclosed and open sections. The cut portion creates an opening that increases air contact area for improved sensitivity, while the remaining enclosed portions continue to provide moisture protection for the internal components.
3Reliability
If injection material is used to protect PCB substrate, then protection from foreign substances is improved, but the conformal coating layer is compromised and moisture protection is reduced
Solution Approach 1:
The injection material is removed from the PCB substrate protection scheme. Instead, a conformal coating layer is applied directly to the PCB substrate, providing effective moisture protection without the harmful effects of injection material.
4Reliability
If the sensor housing is completely sealed to prevent foreign substance ingress, then reliability is improved, but air flow to temperature sensors is blocked and response speed decreases
Solution Approach 1:
The housing is segmented to create a cut portion that allows air flow pathways to the temperature sensors while maintaining sealed sections for foreign substance protection. This segmentation enables simultaneous achievement of reliability and fast response.
Solution Approach 2:
The cut portion is strategically positioned and shaped to preemptively guide air flow toward the temperature sensors, ensuring rapid response while the rest of the sealed housing prevents foreign substance ingress.
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
Improves temperature sensing sensitivity and response speed by allowing air communication, prevents dew condensation, and safeguards PCB components from moisture ingress.
Implementation Method 1
the lower side of the top of the sensor housing has a cut portion which enables foreign substances flowing in between the tip housing and the sensor housing to be discharged at the lower side
Implementation Method 2
protect the PCB substrate from flowing-in moisture by removing an injection material protecting the PCB substrate and forming a conformal coating layer on the PCB substrate
Implementation Method 3
an IR sensor for measuring temperature and a photo sensor for sensing light are packaged together, and an NTC, which is a temperature sensor
Data Source
AI summary
A vehicular indoor temperature sensor is disclosed, which includes: a PCB substrate; a tip sensor unit connected to a front side of the PCB substrate, and which includes a first temperature sensor for detecting the temperature of the outer surface of one side of a tip housing, and a solar radiation sensor for sensing the amount of solar radiation incident on the outer surface of the one side of the tip housing; and a sensor housing, which accommodates at least a portion of the tip sensor unit and at least a portion of the PCB substrate so as to prevent foreign substances from flowing into the PCB substrate from the outside, wherein the lower side of the top of the sensor housing has a cut portion which enables foreign substances flowing in between the tip housing and the sensor housing to be discharged at the lower side.