Rotation Speed Sensor Housing Welding for Waterproof Sealing
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Solution Overview
Problem
Existing rotation speed sensors face challenges in achieving high waterproofing performance without applying pressure or heat loads to substrates or integrated circuits, particularly in environments exposed to liquids like water, such as around vehicle tires.
Innovation Solution
A rotation speed sensor design featuring a cable with a sheath and a housing configuration where a circuit substrate is mounted within a first housing and a cable is held within a second housing, which is welded to the cable's sheath, using laser welding to ensure waterproofing without direct pressure or heat application, and both housings are made of nylon resin to prevent thermal expansion differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a resin mold coating method is used to achieve waterproofing, then waterproofing performance is improved, but load due to pressure or heat is applied to the substrate or IC
Solution Approach 1:
The housing is divided into two separate parts: a first housing that holds the circuit substrate and an IC, and a second housing that holds the cable. This segmentation allows each housing to be molded independently without exposing the IC to excessive pressure or heat, while still achieving waterproofing through the welding connection between the two housings.
Solution Approach 2:
The patent introduces a welding connection as an intermediary method to join the first and second housings. This welding process provides waterproofing performance without requiring the substrate or IC to withstand the pressure and heat that would be applied in a traditional resin mold coating process.
2Reliability
If traditional waterproofing methods are used, then sealing against liquids is achieved, but high-cost waterproofing connectors are required
Solution Approach 1:
The patent merges the waterproofing function into the housing structure itself through welding connections between the first and second housings, and between the second housing and the cable sheath. This eliminates the need for separate, high-cost waterproofing connectors by integrating the sealing function directly into the housing design.
Solution Approach 2:
The patent uses nylon resin for the housings, which can be molded cost-effectively and provides sufficient waterproofing performance when welded. This approach replaces expensive specialized waterproofing connectors with more economical resin materials and welding processes.
3Adaptability or versatility
If different materials are used for housings, then functional requirements are met, but thermal expansion differences cause sealing issues
Solution Approach 1:
The patent uses the same nylon resin material for both the first housing and the second housing. This homogeneity in material composition ensures that both housings have identical thermal expansion characteristics, preventing sealing issues that would arise from thermal expansion differences between dissimilar materials while still meeting all functional requirements.
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 achieves high waterproofing performance for rotation speed sensors without applying loads to the substrate or IC, reducing costs by eliminating the need for high-cost waterproofing connectors and ensuring effective sealing against liquids.
Implementation Method 1
both housings are made of nylon resin to prevent thermal expansion differences
Data Source
AI summary
A rotation speed sensor, configured to detect a rotation speed of a rotating body, is composed of a cable composed of an electric wire including a conductor wire, and a sheath provided over the electric wire, a circuit substrate mounted with an integrated circuit thereon and connected to the conductor wire being exposed from the cable, and a housing including a first housing, which is configured to hold the circuit substrate therein, and a second housing, which is configured to hold the cable therein, with the first housing being welded to the second housing, and with the second housing being welded to a surface of the sheath of the cable.