Composite Pipe Socket Geometry for Flexible Leak-Tight HVAC Joints
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Solution Overview
Problem
Existing composite pipes face limitations in bending flexibility, kinking, pressure-induced leaks, and flow resistance due to their design, which restricts their use in various applications and leads to additional components being necessary for installation and maintenance.
Innovation Solution
A composite pipe kit with a double-walled corrugated design featuring slightly convex contact surfaces and a conical sleeve configuration that prevents inward bulging under pressure, ensuring reliable sealing and flexibility around both axes, and utilizing a ring seal that maintains contact even under external pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the large side wall section is made planar to serve as a support surface, then the pipe can be stably supported, but the ability to bend around the major axis is severely restricted and kinking occurs
Solution Approach 1:
The pipe cross-section is designed with asymmetric side wall configurations: two planar large side wall sections for stable support and two slightly convex small side wall sections for bending flexibility. This asymmetric design allows the pipe to be supported stably on its flat surfaces while maintaining the ability to bend around the major axis without kinking, as the convex small side walls provide the necessary flexibility.
Solution Approach 2:
Different regions of the pipe cross-section are given different geometric properties: the large side wall sections are made planar for support stability, while the small side wall sections are made slightly convex for bending flexibility. This local differentiation of geometric quality allows the pipe to simultaneously achieve stable support and bending capability without requiring additional components.
2Strength
If the convex large side wall section is subjected to compressive load, then the pipe can bear external pressure, but the flat side wall section bulges inwards causing leaks in pipe connections
Solution Approach 1:
The pipe employs asymmetric side wall design where the large side wall sections are planar and the small side wall sections are slightly convex. When external pressure acts on the convex small side walls, they naturally arch outward rather than allowing the planar large side walls to bulge inward, thus maintaining sealing reliability at connections while preserving pressure bearing capacity.
Solution Approach 2:
The slightly convex geometry of the small side wall sections pre-configures the pipe to resist inward bulging of the large side walls under external pressure. The convex shape creates a natural outward arching tendency that counteracts the inward bulging force, preventing loss of contact with socket inner contours and maintaining sealing before failure can occur.
3Ease of manufacture
If connecting elements are inserted inside the composite pipes to connect them, then the pipes can be joined, but the cross section is reduced and steps form in the flow cross section causing pressure losses
Solution Approach 1:
The connection system merges the socket and spigot designs to create a seamless flow path. The socket is designed with a conical configuration that matches the spigot geometry, allowing the spigot end to expand outward and maintain full cross-sectional flow area throughout the connection. This merging of connection geometries eliminates steps in the flow cross-section and prevents pressure losses while maintaining easy connection capability.
Solution Approach 2:
Instead of reducing the cross-section to enable connection (as in traditional internal connecting elements), the design inverts the approach by allowing the spigot end to expand outward to match the socket. This inversion maintains the full flow cross-section throughout the connection, eliminating pressure losses while achieving secure mechanical joining.
4Ease of manufacture
If the composite pipe is designed with fixed geometry for stable support, then manufacturing is simplified, but flexibility around both axes is impaired
Solution Approach 1:
The pipe cross-section employs asymmetric geometry with two planar large side walls for stable support and two slightly convex small side walls for bending flexibility. This asymmetric design maintains manufacturing simplicity through consistent molding processes while providing enhanced flexibility around both major and minor axes, allowing the pipe to adapt to various installation configurations without compromising structural integrity.
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
A composite pipe for air conditioning and ventilation systems has a smooth inner pipe (1) and a corrugated outer pipe (2). It has opposing, semicircular small side wall sections and connecting convex large side wall sections. A double push-fit socket (28) is provided for connecting such pipes. The socket has an inner cross-section corresponding to the outer cross-section of the composite pipe (26), leaving a gap (36). The socket (28) tapers inwards more sharply in the area of the small side wall sections than in the area of the large side wall sections, so that when inserted, the small side wall sections abut against corresponding small socket wall sections (37).