Selective Coating on Drive Device Rear Frame
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Solution Overview
Problem
Existing drive devices for electric power steering systems face challenges in achieving both improved corrosion resistance and effective suppression of radiation noise, as coating processes intended to enhance corrosion resistance can inadvertently increase radiation noise and create long feedback paths for noise transmission.
Innovation Solution
The drive device incorporates a rear frame with specific engaging portions having exposed material for improved conductivity and coated outer portions for corrosion resistance, along with a heat sink and substrate configuration that reduces impedance and forms a short feedback path for noise suppression, utilizing metal connection members and a control unit to manage coil energization and rotation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If coating is applied to all engaging portions and outer wall portions to improve corrosion resistance, then corrosion resistance is improved, but radiation noise increases and feedback path lengthens
Solution Approach 1:
The patent applies coating selectively to only certain engaging portions and outer wall portions of the rear frame, rather than uniformly to all surfaces. Specifically, coating is applied to engaging portions that do not require electrical contact and to outer wall portions exposed to external environments, while leaving engaging portions that serve as noise feedback paths uncoated. This local differentiation resolves the contradiction by providing corrosion protection where needed while maintaining electrical conductivity and short feedback paths where required for noise suppression.
2Reliability
If coating is applied to engaging portions to improve corrosion resistance, then corrosion resistance is improved, but electrical conductivity decreases
Solution Approach 1:
The patent differentiates between engaging portions based on their functional requirements. Engaging portions that serve as noise feedback paths are left uncoated to maintain electrical conductivity, while other engaging portions and outer wall portions are coated for corrosion protection. This selective coating approach allows the structure to simultaneously achieve both corrosion resistance and electrical conductivity in different locations.
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 corrosion resistance and suppresses radiation noise by improving conductive states and reducing impedance, forming efficient feedback paths that effectively manage noise transmission and heat dissipation.
Implementation Method 1
a heat sink fixed to the rear frame on the opposite side of the front frame
Implementation Method 2
heat dissipation
Implementation Method 3
the engagement surface of the specific engaging portion which is a part of the plurality of engaging portions is in a state in which the connection member is in contact with the connection member, and the material of the rear frame is exposed
Implementation Method 4
the other engaging portion other than the specific engaging portion and the outer wall portion of the rear frame exposed to the outside space have a coating
Data Source
AI summary
A rear frame has a plurality of engaging portions engaged with connection members. An engagement surface of the specific engaging portion which is a part of the plurality of engaging portions is in a state in which the connection member is in contact with the connection member, and the material of the rear frame is exposed. Among the plurality of engaging portions, the other engaging portion other than the specific engaging portion and the outer wall portion of the rear frame exposed to the outside space have a coating.