Hinge Assembly with Overlapping Cam Ranges for Road Manhole Covers
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Solution Overview
Problem
Existing hinge assemblies for access covers are fragile, costly, and difficult to manufacture due to loose fastening and weld failures, leading to jamming and poor positioning issues during repeated opening and closing operations.
Innovation Solution
A hinge assembly design featuring overlapping angular ranges for cam and counter-cam cooperation, with partial cylinder-shaped cam surfaces and integral counter-cams, along with support and locking mechanisms to stabilize the lid and prevent tilting, ensuring robustness and ease of manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a hinge assembly with welded plate and hinge pin is used, then the lid can be hinged to the frame, but the fastening screws or bolts can loosen and cause poor positioning and jamming during repeated opening and closing operations
Solution Approach 1:
The hinge assembly is divided into separate modular components: a frame component with cam profile, a lid component with counter-cam profile, and distinct fastening elements. This segmentation eliminates the welded plate structure, preventing fastener loosening and positioning drift while maintaining hinge functionality through the cam-counter-cam mechanism.
2Reliability
If a hinge assembly with multiple shaping and welding steps is used, then the hinge pin can be fastened to the frame, but the manufacturing process becomes costly and complicated
Solution Approach 1:
The cam profile and fastening structure are merged into a single integrated frame component, eliminating separate welded plates and hinge pins. The lid component similarly integrates the counter-cam and mounting features. This merging reduces the number of shaping and welding steps while maintaining structural strength through the cam mechanism design.
3Reliability
If tabs supporting the hinge pin are used, then the hinge pin can be fastened to the plate, but the tabs can fold or separate from the plate under lid force during hinging
Solution Approach 1:
Instead of using tabs that protrude from the plate to support the hinge pin (which can fold or separate), the design inverts the support structure: the cam profile itself provides the structural support and positioning, while fasteners directly attach the frame and lid components without vulnerable intermediate tabs. This inversion eliminates the weak point while maintaining hinge pin support.
Data Source
AI summary
This hinge assembly comprises a lid with a covering web and a hinge adapted for enabling an angular movement of the lid between an open position and a closed position, the hinge including a first cam and a first counter-cam, the first cam and the first counter-cam cooperating over a first angular range. The hinge comprises an additional cam and an additional counter-cam cooperating over an additional angular range. The first angular range and the additional angular range overlap over an angular overlap range that amounts to at least 60° and over the entire range of which both the first cam and counter-cam and the additional cam and counter-cam cooperate simultaneously. The device can be used for road manholes.