Current Sensor Bus Bar Routing for Heat Management
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Solution Overview
Problem
Current sensors used in hybrid and electric vehicles face reduced measurement precision due to increased heat generation in bus bars, which can exceed the heat-resistant temperature of magnetic sensors, leading to inaccurate current measurements.
Innovation Solution
The design incorporates a bus bar with a shortened length and opposing portion that crosses a second direction, reducing heat resistance and allowing magnetic shields to be strategically placed to minimize heat impact on the magnetism sensing portion, while also using heat sinks to dissipate heat effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the bus bar is routed along the side walls and bottom surface of the case to fit the sensor housing, then the storage efficiency is improved, but the bus bar length increases causing excessive heat generation that exceeds the heat-resistant temperature of the magnetic sensor
Solution Approach 1:
The bus bar routing configuration is changed from a conventional path along side walls and bottom surface to a new spatial arrangement where the opposing portion crosses the second direction (width direction) of the chassis. This dimensional repositioning shortens the bus bar length within the case while maintaining connection between terminals, reducing heat generation without compromising storage efficiency.
2Temperature
If the bus bar length is shortened to reduce heat generation, then the temperature around the magnetic sensor is reduced, but the bus bar must be reconfigured which increases manufacturing complexity
Solution Approach 1:
The bus bar is divided into distinct functional portions: a first portion extending in the first direction to connect terminals, and an opposing portion crossing the second direction. This segmentation allows each portion to be optimized independently - the first portion maintains electrical connection function while the opposing portion is configured to minimize heat exposure to the magnetic sensor, simplifying the overall manufacturing process.
3Measurement precision
If the magnetic sensor is placed to face the bus bar for accurate measurement, then the measurement precision is improved, but the sensor is exposed to higher temperatures that reduce measurement accuracy
Solution Approach 1:
The bus bar opposing portion is specifically configured to cross the second direction in the region where the magnetic sensor is located. This creates a localized heat reduction zone around the sensor while maintaining the bus bar's overall electrical connection function. The magnetic sensor retains its optimal positioning for accurate measurement without being exposed to excessive heat from the bus bar.
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 configuration enhances measurement precision by reducing heat-generated errors and maintaining accurate current sensing even under high-temperature conditions, making it suitable for large current measurements.
Implementation Method 1
a magnetism sensing portion placed so as to face the bus bar in a first direction... that detects a magnetic field generated when a current under measurement follows through a bus bar
Implementation Method 2
when the bus bar generates heat due to a flow of a current in the bus bar... the bus bar generates much more heat
Data Source
AI summary
A current sensor has a bus bar through which a current under measurement flows, a magnetism sensing portion placed so as to face the bus bar in an X direction, and a chassis that incorporates the magnetism sensing portion and part of the bus bar. In a Y direction orthogonal to the X direction, the bus bar has a first connection end protruding from a Y1 side of the chassis and a second connection end protruding from a Y2 side of the chassis. The first connection end and second connection end are at different positions in the X direction when viewed from a Z direction orthogonal to the X direction and Y direction. An opposing portion, facing the magnetism sensing portion, of the bus bar crosses the Y direction when viewed from the Z direction.