Piston Assembly Stiffness Insert for Pneumatic Rigidity
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Solution Overview
Problem
Piston assemblies made of plastic deform under high pneumatic pressures due to lack of rigidity and hardness compared to metal components, leading to longer acceleration and deceleration times in pneumatic applications.
Innovation Solution
A piston assembly design featuring two piston portions with an annular stiffness insert clamped between them, providing increased stiffness without significantly increasing mass or inertia, using materials like plastic for the portions and a stiffer material for the insert, along with annular magnet chambers and interlock projections for enhanced stability and sealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If a piston is made of plastic to reduce weight, then the moment of inertia is reduced and acceleration is improved, but the piston deforms under high pneumatic pressures due to insufficient rigidity
Solution Approach 1:
The piston assembly uses a composite structure combining plastic piston portions with a metal stiffness insert. The plastic portions maintain low weight while the metal insert provides the necessary rigidity and strength to resist deformation under high pneumatic pressures, effectively resolving the contradiction between weight reduction and strength maintenance.
Solution Approach 2:
The piston is divided into multiple portions (first piston portion, second piston portion, and stiffness insert) that can be separately manufactured and assembled. This segmentation allows each component to be optimized for its specific function - plastic portions for weight reduction and metal insert for structural rigidity - while working together as an integrated assembly.
2Strength
If a metal piston is used to provide rigidity and hardness, then the piston can withstand high pressures, but the moment of inertia increases and acceleration time increases
Solution Approach 1:
Instead of using a solid metal piston, the invention employs a hybrid construction where only critical structural elements (the stiffness insert) are made of metal, while the majority of the piston body uses lightweight plastic material. This selective use of materials maintains necessary rigidity while minimizing overall weight and moment of inertia.
Solution Approach 2:
The metal stiffness insert is strategically positioned within the piston assembly at locations where rigidity is most needed to withstand pneumatic pressures. This localized application of high-strength material provides structural support only where required, rather than throughout the entire piston, thereby reducing overall weight while maintaining strength where critical.
3Ease of manufacture
If a single plastic piston portion is used, then the piston is lightweight and inexpensive, but it lacks the structural stability and stiffness required for high-pressure applications
Solution Approach 1:
The piston is constructed from multiple separately manufactured portions that are assembled together. The plastic piston portions can be manufactured using cost-effective molding processes, while the metal stiffness insert is manufactured separately and then integrated. This segmentation maintains manufacturing simplicity and cost-effectiveness while achieving the structural stability of a more complex single-piece construction.
Solution Approach 2:
The combination of plastic and metal materials in a composite assembly allows the piston to achieve structural stability comparable to solid metal constructions while retaining the manufacturing advantages and cost benefits of plastic components. The plastic portions are easily molded and assembled, while the metal insert provides the necessary structural reinforcement.
Data Source
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AI summary
A piston portion (102) for a piston assembly (100) is provided according to an embodiment of the invention. The piston portion (102) includes a substantially cylindrical head portion (103) including a mating face (105). The piston portion (102) further includes a substantially annular insert chamber (126) formed in the mating face (105) and adapted for receiving a portion of a substantially annular insert (120).