Molded Piston Non-Circular Column Lateral Stiffness
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Solution Overview
Problem
Pistons used in air springs lack sufficient lateral stiffness and overall strength while being heavy, and their manufacturing processes are inefficient due to high draft angles.
Innovation Solution
A molded piston design featuring a non-circular central column with a chordal surface for lateral stiffness, supported by outer radial webs and inner radial webs, along with threaded inserts for attachment to vehicle suspension components, minimizing weight and draft angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If molded pistons are used in air springs, then weight is reduced compared to steel construction, but lateral stiffness and overall strength are insufficient
Solution Approach 1:
The patent applies asymmetry by changing the central column from a conventional circular cross-section to a non-circular cross-section (such as rectangular or polygonal). This asymmetric geometry provides enhanced lateral stiffness and strength characteristics that are not achievable with symmetric circular sections, while still maintaining the weight advantages of molded plastic construction over steel.
2Ease of manufacture
If conventional molded piston designs are used, then manufacturing is simplified, but draft angles are excessive and manufacturability is reduced
Solution Approach 1:
The patent resolves the draft angle conflict by transitioning from a two-dimensional taper approach to a three-dimensional solution using non-circular cross-sections. The non-circular central column geometry allows for optimized mold design that reduces excessive draft angles while maintaining ease of molding, thereby improving manufacturing efficiency without sacrificing manufacturability.
3Ease of manufacture
If circular central column design is used, then manufacturing is easier, but lateral stiffness under asymmetrical forces is insufficient
Solution Approach 1:
The patent directly addresses this contradiction by replacing the circular central column with a non-circular cross-section. This asymmetric geometry is specifically designed to provide enhanced lateral stiffness and strength characteristics that better resist asymmetrical forces encountered in vehicle suspension applications, while remaining manufacturable through molding processes.
Data Source
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AI summary
A molded piston (30) for an air spring (10) for a vehicle comprises an outer shell (32), a non-cylindrical central column (34) configured for providing lateral stiffness and strength to the outer shell (32) by being braced in its relation to said outer shell (32) by outer radial webs (46), and an upper surface (50) having a recessed lower end closure seating surface (52). The non-cylindrical central column (34) further includes a mounting stud sleeve and hole (40) braced in its relation to the non-cylindrical central column (34) by inner radial webs (44), wherein the mounting stud sleeve and hole (40) includes a spline (68) within the mounting stud sleeve and hole (40) having an inner diameter that remains constant along its length, and having an outer diameter that tapers inward along its length.