Hall Sensor Thermal Isolation in Resin Molding
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Solution Overview
Problem
The existing torque sensor manufacturing process using Hall ICs in resin molding faces a challenge where the high temperature of the molten resin can lead to a decrease in detection accuracy due to heat exposure.
Innovation Solution
A sensing device and manufacturing method where the sensor main body, including a sensing element and lead wires, is housed in a container part within a housing member, and a mold resin is molded around this housing member without contacting the sensor main body, thereby isolating it from the molten resin's heat.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the Hall ICs are molded in a resin member together with magnetic collecting rings, then the sensor can be integrated and manufactured efficiently, but the detection accuracy decreases due to heat exposure from molten resin
Solution Approach 1:
The invention divides the molding process into two separate stages: first molding the magnetic collecting rings, then removing them to create a cavity for the Hall ICs before final molding. This segmentation prevents the Hall ICs from being exposed to molten resin heat while maintaining the integrated structure benefit.
Solution Approach 2:
The magnetic collecting rings serve as an intermediary element that is temporarily present during the first molding stage, then removed to create space for the Hall ICs. This intermediary approach allows the Hall ICs to be positioned accurately without direct exposure to harmful molten resin.
2Productivity
If molten resin at high temperature is injected into the molding space, then the resin molding process can be completed, but the Hall ICs suffer heat damage reducing detection accuracy
Solution Approach 1:
The magnetic collecting rings are molded first, and the Hall ICs are positioned in the created cavity before the final resin injection. This preliminary action ensures that the Hall ICs are already in place and protected when the molten resin is injected, preventing heat damage.
Solution Approach 2:
The magnetic collecting rings are removed after the first molding stage to create a cavity, extracting the space needed for Hall IC placement. This extraction allows subsequent molding without exposing the Hall ICs to molten resin heat.
3Shape
If the Hall ICs are arranged in the molding space with magnetic collecting rings, then the sensor structure can be formed, but the sensor main body contacts molten resin causing heat exposure
Solution Approach 1:
The molding process is segmented into two phases: first forming the magnetic collecting rings, then creating the final sensor housing around the positioned Hall ICs. This segmentation ensures the sensor main body never contacts molten resin while achieving the desired structural integration.
Solution Approach 2:
The magnetic collecting rings act as an intermediary structure that facilitates proper positioning and spacing, ensuring the Hall ICs are correctly positioned without direct contact with molten resin during the molding process.
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 approach effectively prevents a decrease in detection accuracy by isolating the sensor from the heat of the molten resin during molding, ensuring reliable performance of the magnetic field sensor.
Implementation Method 1
a Hall IC as a sensor for detecting a magnetic field... detects torque applied to a steering wheel of a vehicle based on variation in strength of a magnetic field detected by the Hall IC
Data Source
AI summary
A sensor module includes a magnetic field sensor that includes a sensor main body including a magnetic field sensing element and a plurality of lead wires led out from the sensor main body, a container case including a container part that includes the sensor main body, and a molded body that includes a mold resin molded so as to include at least a part of the container case without contacting with the sensor main body.