Current Sensor Thermal Insulation for High Load
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Solution Overview
Problem
Current sensors used in high-load applications, such as electric vehicles, face challenges in maintaining measurement accuracy due to increased heat generation from the bus bar, which can exceed the heat-resistant temperature of electronic components like magnetic detectors.
Innovation Solution
A current sensor design that includes a bus bar with an exposed surface facing the magnetic detector, separated by an air layer acting as a low thermal conductivity material, which reduces heat transfer from the bus bar to the magnetic detector, thereby suppressing temperature increases around the magnetic detector.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the bus bar current to be measured increases, then the measurement capability is improved, but the heat generation increases causing the magnetic detector temperature to rise above its heat-resistant temperature
Solution Approach 1:
A resin-based material is introduced as an intermediary thermal management layer between the bus bar and the magnetic detector. This material serves as a thermal barrier that reduces heat transfer from the bus bar to the magnetic detector, allowing the system to handle higher currents without overheating the detector.
Solution Approach 2:
The resin-based material is selectively positioned only in the region where heat transfer from the bus bar to the magnetic detector occurs. This localized application provides thermal management exactly where needed, preventing heat buildup around the magnetic detector while allowing other components to operate normally.
2Ease of manufacture
If resin-based material is used to cover the bus bar for fluidity during molding, then the manufacturing process is improved, but heat transfer to the magnetic detector increases
Solution Approach 1:
The thermal conductivity parameter of the resin-based material is carefully selected and controlled. The material is formulated to have specific thermal properties that balance two requirements: providing sufficient fluidity during the molding process and providing adequate thermal insulation to protect the magnetic detector from heat.
3Strength
If the bus bar is covered with resin-based material, then the structural integrity is improved, but the thermal insulation performance deteriorates
Solution Approach 1:
The resin-based material is applied locally only in the specific region between the bus bar and magnetic detector where thermal insulation is needed. This localized application provides the necessary thermal barrier while maintaining structural integrity in other areas through the case member structure.
Solution Approach 2:
The solution employs a composite structure combining the resin-based material with the case member and bus bar. This composite approach allows the resin to provide both structural support and thermal insulation properties, while the overall case structure provides additional mechanical strength and protection.
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 proposed design effectively reduces the temperature around the magnetic detector, allowing for increased current measurements without compromising detection accuracy or shortening the product life, thus enhancing the reliability of current sensors in high-load applications.
Implementation Method 1
A low thermal conductivity material having a lower thermal conductivity than a resin-based material forming the case is provided between the bus bar and the magnetic detector
Data Source
AI summary
A current sensor which suppresses deterioration of detection accuracy caused by high temperature of electronic components due to heat of a bus bar and is suitable for measurement of large current includes a bus bar through which a current to be measured flows, a magnetic detector detecting a magnetic field generated by the bus bar, and a case integrally formed with the bus bar and having a storage space storing the magnetic detector. The magnetic detector is spaced away from and faces the bus bar. The bus bar is on a first surface of the storage space defining the storage space and facing the magnetic detector. A low thermal conductivity material having a lower thermal conductivity than a resin-based material forming the case is provided between the bus bar and the magnetic detector to contact an opposing surface, on the bus bar, facing the magnetic detector.