Manhole Cover Frame with Conical Underside for Load Distribution
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Solution Overview
Problem
Existing manhole covers transfer driving loads unevenly to manhole structures, causing increased surface pressure and bending loads on compensating rings, leading to potential material damage and displacement issues.
Innovation Solution
The manhole cover design features a radially outer recess on its underside to match the diameter of the manhole neck or compensating ring, with a conical peripheral surface and groove-shaped recesses for enhanced support and anti-twist protection, and an integrated joint seal for improved sealing and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the frame has a cylindrical peripheral surface with diameter matching the manhole neck, then the frame is secured against horizontal displacement, but the driving loads are transferred unevenly to the manhole structure causing increased surface pressure and bending loads on compensating rings
Solution Approach 1:
The frame's peripheral surface is divided into different zones with different geometries: an upper cylindrical section for stability and a lower conical section for even load distribution. This local differentiation allows the frame to simultaneously achieve horizontal displacement resistance and uniform stress distribution on the compensating ring.
Solution Approach 2:
The frame design transitions from a two-dimensional cylindrical surface to a three-dimensional conical surface in the lower section. This dimensional change allows the frame to distribute loads over a larger area and at different angles, converting concentrated vertical loads into distributed oblique forces that reduce surface pressure on the compensating ring.
2Stability of the object's composition
If the frame diameter is selected to match the manhole neck diameter, then the frame is secured against horizontal displacement, but this leads to uneven force distribution and potential material damage
Solution Approach 1:
The frame employs different geometric qualities at different locations: the upper cylindrical portion provides stable positioning matching the manhole neck diameter, while the lower conical portion with larger diameter provides enhanced load distribution capacity. This local quality differentiation protects the compensating ring material from excessive bending stresses.
Solution Approach 2:
The conical lower section of the frame acts as a cushioning element that distributes and softens the impact of driving loads before they reach the compensating ring. This pre-cushioning effect reduces peak stresses and prevents material damage to the compensating ring.
3Ease of manufacture
If a conventional cylindrical frame is used, then the installation is simple, but on-site joint sealing is required which increases installation time and complexity
Solution Approach 1:
The sealing function is merged with the structural frame by integrating a sealing ring into the frame's lower conical section. This combination eliminates the need for separate on-site sealing operations, reducing installation complexity while maintaining the simple cylindrical upper geometry for easy manufacturing.
Solution Approach 2:
The sealing ring is pre-installed on the frame during manufacturing rather than requiring on-site installation. This preliminary action transfers the sealing task from the complex on-site installation phase to the controlled manufacturing phase, simplifying the installation process while maintaining manufacturing simplicity.
Data Source
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AI summary
Manhole cover (30) for arrangement on a manhole neck or a compensating ring (14) of a manhole structure, and manhole structure with a manhole cover (30) arranged on a manhole neck or a compensating ring (14), wherein the manhole cover has a frame (31) for receiving a manhole lid (32), wherein the frame has a bearing surface (41) on a frame underside (40) for resting on an end face of the manhole neck or an end face (44) of a compensating ring (14) arranged on the manhole neck, wherein, when the manhole cover is arranged on the manhole neck or the compensating ring (14), the frame underside (40) corresponds to the end face (44) of the manhole neck or the compensating ring (14) both in its surface contour and in its diameter.