Transmission Case Rib Layout for Balanced Casting Flow
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Solution Overview
Problem
The formation of cavities during the casting process of transmission cases due to imbalanced molten metal flow, particularly in areas without recesses for ribs, leads to reduced yield and increased manufacturing defects.
Innovation Solution
The introduction of additional ribs, including a second rib connected to a pin boss, which promotes balanced molten metal distribution and reduces the occurrence of cavities by ensuring uniform metal flow during casting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If ribs are provided between the circular ring part and bolt bosses to increase strength, then the structural strength is improved, but cavities occur during casting due to imbalanced molten metal flow
Solution Approach 1:
The patent applies local quality by providing ribs only at specific locations where strength is needed, while intentionally omitting ribs at other locations to enable proper molten metal flow during casting. This selective placement of structural elements resolves the contradiction between achieving sufficient strength and preventing casting defects.
Solution Approach 2:
The patent segments the rib structure into multiple individual ribs positioned at specific intervals around the circular ring part, rather than providing continuous ribs. This segmentation allows molten metal to flow through the gaps between ribs, preventing cavity formation while still providing adequate structural reinforcement at key locations.
2Adaptability or versatility
If holes for components or thick parts for oil passages are formed between the bolt boss and circular ring part, then functional requirements are met, but ribs cannot be provided in those locations leading to casting imbalances
Solution Approach 1:
The patent performs preliminary action by strategically planning the rib layout in advance to account for the positions of holes and oil passages. The rib positions are predetermined to avoid these functional features, ensuring that both the functional requirements (holes and passages) and casting quality are satisfied without conflict.
3Productivity
If molten metal flow is imbalanced during casting, then cavities occur reducing yield, but adding more ribs to balance flow increases structural complexity
Solution Approach 1:
The patent applies partial action by providing ribs only at the necessary locations to achieve adequate structural strength and acceptable molten metal flow balance, rather than adding ribs everywhere. This selective approach achieves sufficient flow balance to prevent cavities and improve yield without unnecessarily increasing structural complexity.
Data Source
AI summary
A case that houses a drive force transmission device includes a circular ring part, fastening boss parts, first ribs, a non-fastening boss part, and a second rib. The circular ring part defines an opening through which a shaft is configured to be inserted. The fastening boss parts are provided around the circular ring part. Fastening members are to be secured to the fastening boss parts. The first ribs are respectively formed between a portion of the fastening boss parts and the circular ring part when viewed from an axial direction of the shaft. The non-fastening boss part is provided between adjacent ones of the fastening boss parts to which the first ribs are not connected, when viewed from the axial direction. A fastening member is not configured to be secured to the non-fastening boss part. The second rib is formed between the non-fastening boss part and the circular ring part.