Power Conversion Device Corrosion-Resistant Case Sealing
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Solution Overview
Problem
The existing power conversion devices in vehicles face a decrease in sealing properties between the case and the outer refrigerant pipe due to corrosion, especially in coastal and cold regions where aqueous solutions like sea water and calcium chloride solutions can stick to the case, leading to corrosion and reduced adhesiveness of the O-ring, which compromises the sealing effectiveness.
Innovation Solution
A power conversion device is designed with a metallic case body and a corrosion-resistant portion that is less prone to corrosion, where the fixed member is attached to this portion via a seal member, preventing corrosion at the contact region and maintaining the sealing properties between the case and the fixed member.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the case is made entirely from corrosion-resistant material, then corrosion resistance is improved, but material costs increase
Solution Approach 1:
The patent applies local quality by making only the specific portion of the case that contacts the seal member corrosion-resistant, rather than the entire case. This targeted approach provides corrosion protection exactly where it is needed to maintain sealing properties, while using cost-effective materials for the rest of the case structure, thereby resolving the contradiction between reliability and manufacturing cost.
2Reliability
If a seal member is used between the case and fixed member, then sealing properties are improved, but corrosion at the contact surface reduces sealing effectiveness
Solution Approach 1:
The patent applies preliminary anti-action by pre-treating the contact surface with corrosion-resistant material before the seal member is installed. This preventive measure counteracts the harmful effect of corrosion before it can occur, ensuring that the seal member maintains its sealing effectiveness against aqueous solutions throughout the device's operational life.
3Ease of manufacture
If the case is made from aluminum by die-casting, then manufacturing ease is improved, but corrosion resistance in harsh environments deteriorates
Solution Approach 1:
The patent resolves this contradiction by maintaining the cost-effective aluminum die-casting process for the majority of the case while applying corrosion-resistant material only to the specific contact surface that requires protection. This selective approach preserves the manufacturing advantages of die-casting while providing targeted corrosion resistance for harsh environmental conditions.
Data Source
AI summary
A power conversion device that can prevent decrease in sealing properties between a case and a fixed member. The power conversion device has a case, a fixed member, and a seal member. The case has a metallic case body. The fixed member is fixed to the case from the outside of the case. The seal member adheres closely to both the case and the fixed member to ensure water-tightness between the case and the fixed member. The case is partly formed with a corrosion-resistant portion that is less likely to suffer corrosion than the case body. The fixed member is attached to the corrosion-resistant portion via the seal member.