In-Vehicle ECU Metal Bracket Shielding for Noise Reduction
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Solution Overview
Problem
In-vehicle electronic control units face challenges in reducing AM band radiation noise while minimizing weight and part count, as existing solutions either increase weight and cost with metal cases or complicate the design with additional parts.
Innovation Solution
An in-vehicle electronic control unit design featuring a circuit board with a resin member and a metal bracket that includes a first shield portion on the upper surface and a second shield portion on the side surface of the resin member, functioning as an electromagnetic shield to reduce radiation noise and acting as an antenna to ground noise, thereby minimizing weight and part count.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a metal case is used instead of a resin member, then radiation noise is reduced, but weight and cost increase
Solution Approach 1:
The patent combines the electromagnetic shielding function with the mounting bracket by integrating a shield portion into the bracket structure. This allows the bracket to simultaneously serve as both a mounting component and a radiation shield, reducing the need for a full metal case while maintaining noise reduction effectiveness.
Solution Approach 2:
Instead of using a complete metal case for shielding, the patent applies shielding only in specific locations where radiation noise needs to be blocked. The shield portion is strategically positioned within the bracket to target radiation sources while minimizing overall metal usage, thus reducing weight compared to a full metal enclosure.
2Object-generated harmful factors
If an electromagnetic wave shield plate is added to cover electronic parts, then radiation noise is reduced, but the number of parts increases
Solution Approach 1:
The electromagnetic shielding function is merged with the mounting bracket by integrating a shield portion directly into the bracket structure. This eliminates the need for a separate shield plate component, reducing the total part count while maintaining shielding effectiveness.
Solution Approach 2:
The bracket is designed to perform multiple functions: mechanical mounting of the circuit board and electromagnetic shielding. By making the bracket multi-functional, the patent eliminates the need for separate dedicated shielding components, thereby reducing device complexity.
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 design efficiently reduces radiation noise by up to several tens of decibels while minimizing weight and part count compared to using a metal case, and achieves cost savings by leveraging the metal bracket's dual functionality as a shield and attachment mechanism.
Implementation Method 1
the metal bracket includes a first shield portion and a second shield portion... the first shield portion is arranged to only a part of the upper surface of the resin member so that when projected in a winding axis direction of the coil, the first shield portion overlaps at least a part of the coil
Implementation Method 2
mainly by reflection loss resulting from mismatching of intrinsic impedances and attenuation loss resulting from skin effects, spacial conduction of radiation noise can be cut off
Implementation Method 3
AM band radiation noise generated by the coil
Data Source
AI summary
An in-vehicle electronic control unit includes a circuit board equipped with a coil and a power supply circuit, a resin member covering the circuit board, and a metal bracket fixed to the resin member for attaching the circuit board to a vehicle. The metal bracket includes a first shield portion and a second shield portion. The first shield portion is arranged to only a part of an upper surface of the resin member so that when projected in a winding axis direction of the coil, the first shield portion overlaps at least a part of the coil. The second shield portion extends from the first shield portion in the winding axis direction of the coil and is arranged to only a part of a side surface of the resin member.