Insert-Molded Current Sensor Magnetic Shield Rustproofing

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Current sensors with insert-molded magnetic shields face issues with rusting due to exposed portions not receiving rustproofing treatment, leading to increased processing and management costs.

Innovation Solution

The design incorporates a magnetic shield with rustproofed exposure portions, utilizing inorganic or organic rustproofing treatments, and a manufacturing method where a metal plate with pre-rustproofed surfaces is embedded in a case via insert molding, eliminating the need for additional rustproofing treatments.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If the magnetic shield is provided by insert molding with locating pins, then the positional relationship between the case and magnetic shield is accurately controlled, but holes are created in the magnetic shield that expose portions without rustproofing treatment

Engineering Contradiction:

Improvepositional relationship controlVSAvoidrust prevention

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The magnetic shield is pre-rustproofed before being placed in the mold, so that when the locating pins create holes during insert molding, the exposure portions are already protected against rust. This preliminary rustproofing action eliminates the need for post-molding rustproofing treatments while maintaining the precision positioning benefits of insert molding.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If separate rustproofing treatment is applied to exposed portions, then corrosion is prevented, but processing cost and management cost increase

Engineering Contradiction:

Improvecorrosion preventionVSAvoidprocessing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

By applying rustproofing treatment to the entire magnetic shield surface before insert molding, the invention eliminates the need for separate post-molding rustproofing treatments of exposed portions. This preliminary comprehensive treatment simplifies manufacturing processes and reduces overall processing costs while ensuring complete corrosion protection.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The invention merges the rustproofing treatment step with the magnetic shield fabrication process, treating the entire shield surface before molding rather than separating rustproofing into a distinct post-molding operation. This consolidation reduces management complexity and processing costs.

Inventive Principle:

Principle #5Merging (Combining)

3Reliability

If the magnetic shield is made of iron-based alloy for shielding effectiveness, then magnetic shielding performance is improved, but the material becomes susceptible to rust and corrosion

Engineering Contradiction:

Improvemagnetic shielding performanceVSAvoidrust and corrosion

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The invention uses a composite structure combining iron-based alloy (for magnetic shielding performance) with rustproofing materials or coatings (for corrosion resistance). This composite approach allows the magnetic shield to maintain its effective shielding properties while being protected against rust through the integrated rustproofing layer applied before molding.

Inventive Principle:

Principle #40Composite materials

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 prevents rusting and reduces costs by ensuring rustproofed exposure portions within the current sensor, maintaining measurement accuracy and shielding effectiveness without additional rustproofing treatments.

Implementation Method 1

a magnetic shield having a base that faces the busbar, at least a portion of the base facing a side of the busbar opposite to a side where the magnetic sensor is disposed

Methodology Applied

Scientific EffectMagnetic shielding: Magnetic Field

Implementation Method 2

the exposure portions have rust-prevention properties

Methodology Applied

Scientific EffectRust prevention: Oxidation

Data Source

PatentUS20240361358A1Current sensor and method of manufacturing insert-molded component

Publication Date: 2024.10.31 ALPS ALPINE CO LTD

AI summary

A current sensor includes a busbar extending in a direction, a magnetic sensor facing the busbar in a direction intersecting the direction in which the busbar extends, a magnetic shield having a base that faces the busbar, at least a portion of the base facing a side of the busbar opposite to a side where the magnetic sensor is disposed, and a case having an insert-molded section in which at least a part of the magnetic shield is insert-molded. The insert-molded section has holes (first holes), and in the holes (first holes), some portions of the magnetic shield are exposed as exposure portions (first exposure portions) and the exposure portions (first exposure portions) have rust-prevention properties. Such a current sensor has the rustproofed exposure portions and thus problems caused by rusting in the exposure portions in the magnetic shield can be prevented or reduced.