Overmolded Diaphragm Pump Frame with Mechanical Lock
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Solution Overview
Problem
Air operated double diaphragm pumps face challenges with high material costs, mechanical strength, and bolt torque relaxation due to material deformation under load, while existing solutions often rely on reinforcing fillers that come into contact with the fluid.
Innovation Solution
The design involves creating fluid housings and manifolds in two parts: a molded inner frame of fiber reinforced plastic (such as glass fiber reinforced polypropylene or carbon fiber reinforced PVDF) overmolded with polypropylene, conductive polypropylene, or PVDF, focusing on mechanical locking instead of chemical adhesion, and offering an alternative laminate option for the material contact surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If reinforcing fillers are added to the entire part to increase mechanical strength and stiffness, then the mechanical strength and stiffness are improved, but the material cost increases and the frame material comes into contact with the fluid
Solution Approach 1:
The patent applies local quality by adding reinforcing fillers only to specific areas of the pump housing where mechanical strength is needed, rather than throughout the entire part. The encapsulating material with fillers is localized to provide structural support while leaving other areas as simple molded plastic, thus reducing overall material cost and preventing fluid contact with filled material in non-structural areas.
Solution Approach 2:
The patent uses composite materials by combining encapsulating material containing reinforcing fillers with a molded plastic material. This creates a composite structure where the filled material provides mechanical strength and stiffness where needed, while the plain molded plastic provides fluid contact surfaces and overall housing structure, optimizing both performance and cost.
2Strength
If reinforcing fillers are added to the material to increase mechanical strength and stiffness, then the mechanical strength and stiffness are improved, but the material deforms under load causing bolt torque relaxation
Solution Approach 1:
The patent applies local quality by strategically placing encapsulating material with reinforcing fillers in areas subject to high stress and load, such as mounting surfaces and structural ribs. This localized reinforcement prevents deformation under load in critical areas without requiring fillers throughout the entire housing, thereby preventing bolt torque relaxation where it matters most while maintaining overall structural stability.
Solution Approach 2:
The patent uses composite materials to create a hybrid structure where the encapsulating material with fillers provides enhanced mechanical properties and dimensional stability under load, while the molded plastic material provides the base structure. This composite approach ensures that load-bearing areas maintain their shape and prevent deformation, thereby preventing bolt torque relaxation.
3Strength
If the frame is made with fiber reinforced plastic to increase mechanical strength, then the mechanical strength is improved, but the molding time increases and material cost increases
Solution Approach 1:
The patent applies local quality by using fiber reinforced plastic (encapsulating material with fillers) only in specific high-stress areas of the housing, rather than for the entire housing. This localized use of expensive, time-consuming reinforced material provides necessary mechanical strength where needed while keeping overall molding time and material cost lower compared to making the entire housing from reinforced plastic.
Solution Approach 2:
The patent uses composite materials by combining fiber reinforced encapsulating material with standard molded plastic. This composite approach allows the housing to achieve adequate mechanical strength through the reinforced portions while the majority of the housing can be molded from standard plastic more quickly and cheaply, thus reducing overall molding time and material cost while maintaining necessary strength.
4Ease of manufacture
If chemical adhesion is used to bond the encapsulating material to the molded plastic, then the bonding is simple, but the bond may fail due to chemical attack or mechanical stress
Solution Approach 1:
The patent applies merging by integrating the encapsulating material and molded plastic into a unified, monolithic structure where the materials are thoroughly intermixed during the molding process. This merging creates a diffuse interface between materials rather than a distinct boundary, eliminating the need for separate bonding operations and creating a bond that is resistant to chemical attack and mechanical stress throughout the entire interface zone.
Solution Approach 2:
The patent uses composite materials to create a hybrid structure where encapsulating material with fillers is combined with molded plastic in a way that creates a robust, integrated bond. The composite nature of the materials, with their intermixed molecular structures at the interface, provides superior bond stability compared to simple chemical adhesion, resisting both chemical degradation and mechanical failure while maintaining manufacturing simplicity.
Data Source
AI summary
The fluid section of an air operated double diaphragm pump 10 consists of two fluid housings 12, an inlet manifold 14, and an outlet manifold 16. The housings are to be made in two parts. The preferred frame 18 material is glass fiber reinforced with polypropylene that is overmolded into final shape with an encapsulating material 20. The frame 18 is designed so that the encapsulating material 20 can flow from one side to the other allowing for a mechanical lock between the top surface 22 and the bottom so as not to rely on chemical adhesion between the two materials.