Resin Valve Boss Rib Layout for Stable Shaft Positioning
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Solution Overview
Problem
The use of resin housings in valve devices for electric vehicles can lead to cracking and reduced accuracy in flow rate control due to the formation of welds during injection molding, which compromises the strength and stability of the boss, affecting the radial position of the shaft and movable valve.
Innovation Solution
The integration of ribs at specific locations on the boss, offset from the central axis, strengthens the weld areas and balances resin strength, limiting deformation and crack generation during press-fitting, ensuring precise control of the cross-sectional area of the passage opening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If the housing is made of resin and injection molded, then the weight and manufacturing cost are reduced, but welds form during injection molding which compromise the strength and stability of the boss
Solution Approach 1:
The patent applies local quality by adding ribs specifically at locations where welds are likely to form during injection molding. These ribs reinforce only the critical boss areas affected by welds, rather than uniformly strengthening the entire housing. This localized reinforcement maintains the overall lightweight resin construction while selectively improving the strength where it is most needed.
2Stability of the object's composition
If the boss is strengthened to prevent cracking, then the radial position stability is improved, but the device complexity increases
Solution Approach 1:
The patent segments the boss structure by adding discrete ribs at specific locations rather than creating a uniformly complex reinforced structure. These ribs are strategically placed only where welds occur, dividing the reinforcement function into separate, localized elements. This segmentation approach improves radial position stability without unnecessarily increasing overall device complexity.
Data Source
AI summary
A boss is shaped in a tubular form and is injection molded integrally with a housing that forms a flow passage. A ring member is press-fitted to an inner peripheral wall of the boss. A shaft placed on a radially inner side of the ring member is configured to be rotated about a central axis. A movable valve is coupled to a portion of the shaft and is configured to adjust a size of a cross-sectional area of a passage opening at the flow passage. Each of gate marks of the housing is a trace of a site of the housing where molten resin is injected at a time of injection molding of the housing. Each of ribs radially inwardly projects from the inner peripheral wall of the boss and is placed at a corresponding location of the boss which is between adjacent two of the gate marks.