Manhole Cover Latch Assembly Pressure Release Mechanism
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Solution Overview
Problem
Manhole covers can be dislodged by sudden pressure increases due to events like explosions or flooding, potentially causing them to be launched into the air and leading to damage or injury, and existing solutions may damage the frame or surface they are secured to.
Innovation Solution
A manhole cover assembly with a latch and lug system that allows controlled displacement and pressure dissipation, featuring a latch housing, latch plunger, and extractor rails to safely release pressure and facilitate easy removal without damaging the frame or surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a heavy cast iron manhole cover is used to prevent dislodging and unauthorized access, then security and stability are improved, but the risk of dangerous launch during pressure events increases
Solution Approach 1:
The patent converts the harmful effect of pressure buildup into a beneficial controlled release mechanism. The follower arm is positioned to engage the stop feature at a predetermined location, creating a controlled discharge path that safely releases pressure events (explosions, flooding) while preventing the manhole cover from being launched into the air. The harmful pressure is transformed into a controlled ejection of debris through a safe trajectory.
Solution Approach 2:
The stop feature acts as an intermediary element between the follower arm and the manhole cover. When pressure builds up, the follower arm engages the stop feature, which mediates the force transmission and directs it along a controlled path. This intermediary mechanism prevents direct transmission of full pressure force to the manhole cover, thereby preventing dangerous launch while still allowing pressure relief.
2Reliability
If existing pressure release solutions are implemented, then pressure dissipation is improved, but damage to the frame or surface occurs
Solution Approach 1:
The patent applies local quality by creating a specific localized discharge path through the stop feature and follower arm engagement. Instead of general pressure release that could damage the entire frame or surrounding surface, the design concentrates the pressure release in a controlled local area. The stop feature is positioned to create a predetermined discharge trajectory that directs pressure release away from critical frame structures and surface areas.
Solution Approach 2:
The manhole cover is pre-configured with the stop feature and the latch assembly is pre-positioned with the follower arm aligned to engage the stop at a predetermined location. This preliminary arrangement ensures that when pressure builds up, the discharge path is already established and ready to redirect pressure forces safely, preventing frame or surface damage before the pressure event occurs.
3Reliability
If a latch assembly with stop feature is added to enable controlled discharge, then pressure release safety is improved, but device complexity increases
Solution Approach 1:
The latch assembly serves multiple functions: it provides the primary locking mechanism to secure the manhole cover to the frame, and simultaneously incorporates the pressure release function through the follower arm and stop feature interaction. This multi-functionality reduces the need for separate pressure relief devices, thereby limiting the increase in overall device complexity while achieving controlled pressure release.
Solution Approach 2:
The patent merges the pressure release mechanism with the existing latch assembly structure. The follower arm is integrated into the latch housing, and the stop feature is incorporated as part of the latch lever or housing structure. By combining these functions into a single integrated assembly, the design avoids adding separate complex pressure relief devices, thus minimizing the increase in device complexity.
Data Source
AI summary
An example manhole cover assembly includes a manhole cover and a latch assembly. The manhole cover is supportable by a seat of a manhole frame. The latch assembly includes a latch housing fixedly coupled to the manhole cover. A latch plunger is slidably coupled to the latch housing. The latch plunger includes a follower arm. A latch lever is rotatably coupled to the latch housing. The latch lever includes a stop. The latch lever is rotatable relative to the latch housing between a locked position and an unlocked position. The stop is structured to engage the manhole frame when the latch lever is rotated to unlocked position so as to force the manhole cover away from the frame.