Laminated Pump Membrane Insert Locking Against Air Ingress
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Solution Overview
Problem
Laminated membranes in membrane pumps face detachment issues due to high surface forces and pressurized air entering the gap between the elastomeric body and the insert, especially with thermoplastic elastomers, leading to incomplete bonding and potential disconnection.
Innovation Solution
A one-piece elastomeric body with a throughgoing hole in the lower wall and interengaging formations with the insert provides a form-fit connection, preventing radial detachment and air entry, enhanced by a thickened edge and circumferential grooves for an active seal, and a two-part insert design for improved form fit and sealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If thermoplastic elastomer is used for the elastomeric body to simplify manufacturing, then ease of manufacture is improved, but the elastomeric body detaches from the insert due to high surface forces
Solution Approach 1:
A chemically adhesive layer is introduced as an intermediary between the thermoplastic elastomer body and the metal insert. This adhesive layer mediates the bonding interface, enabling reliable attachment of the elastomeric body to the insert without requiring complex mechanical interlocking structures, thus maintaining manufacturing simplicity while ensuring bonding reliability.
Solution Approach 2:
The solution employs a composite structure consisting of three distinct material layers: the thermoplastic elastomer body, the chemically adhesive intermediate layer, and the metal insert. This composite material approach combines the advantages of each material - the elastomeric properties of TPE, the bonding capability of the adhesive layer, and the structural strength of the metal insert - to resolve the detachment problem while preserving ease of manufacture.
2Device complexity
If the elastomeric body is attached without additional adhesive to reduce complexity, then device complexity is reduced, but pressurized air penetrates into the gap causing separation
Solution Approach 1:
The chemically adhesive layer serves as a sealing intermediary that eliminates gaps between the elastomeric body and insert. This adhesive layer acts as a barrier that prevents pressurized air from penetrating into the interface region, thereby preventing the harmful effect of air ingress that would otherwise cause separation and reduce pump efficiency.
Solution Approach 2:
The adhesive layer, while adding a small amount of complexity, converts the potential harm of air ingress into a benefit by creating a sealed interface. The same adhesive bonding function simultaneously provides both mechanical attachment and air sealing, transforming what would be a harmful gap into a beneficial sealed joint.
3Ease of manufacture
If openings are provided in the insert for liquid elastomer injection, then ease of manufacture is improved, but compressed air can still penetrate into the area between elastomeric body and insert
Solution Approach 1:
The chemically adhesive layer is applied as a continuous sealing intermediary that covers not only the outer surface of the insert but also the inner surfaces of the injection openings. This adhesive layer fills and seals the openings from the inside, preventing compressed air from penetrating through these manufacturing-access openings into the gap between the elastomeric body and insert, while still allowing the openings to serve their manufacturing purpose.
Data Source
AI summary
A diaphragm for a pump has a one-piece elastomeric body centered on an axis and formed with an annular outer clamping edge, an annular flexible web extending radially inward from the outer edge, and a core joined by the web to the outer edge and formed in turn by an upper wall and a lower wall axially spaced therefrom. This lower wall is formed on the axis with a throughgoing hole. An insert between the walls extends through the hole, and interengaging formations on the insert and on the lower wall radially couple the insert to the lower wall at an inner edge of the hole.