Back Pressure Flap Valve Locking Mechanism
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Solution Overview
Problem
Existing back pressure flap valve arrangements in ducting systems fail to instantaneously and reliably close off ducting during adverse pressure waves, potentially allowing flames and sparks to propagate back, and may be compromised by high explosion loads or normal operational forces.
Innovation Solution
A back pressure flap valve arrangement with a locking device comprising a locking pin and a stopping member, where the locking pin is biased towards a locking position and held in a retracted position by a stopping member, allowing instantaneous closure upon high back pressure and maintained by controlled mechanical interlocking, with a flexible sealing to prevent activation by gravity or normal pivoting, and a stiffener to prevent deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a locking mechanism is provided to prevent rebound of the flap during normal operation, then the reliability of the valve is improved, but the device complexity increases
Solution Approach 1:
The locking device is designed to automatically engage and lock the flap in the closed position during an explosion event without requiring external intervention. The stopping member and locking pin work together in a self-activating manner, where the pressure wave itself triggers the locking mechanism through the interaction between the stopping member and locking pin, eliminating the need for complex external control systems
Solution Approach 2:
The locking function is extracted as a separate, dedicated mechanism (locking device with stopping member and locking pin) that operates independently from the main flap structure. This modular approach allows the locking function to be simplified and optimized separately, reducing overall system complexity while maintaining reliability
2Strength
If the flap and locking mechanism are designed to withstand high explosion loads, then the strength is improved, but the device complexity increases
Solution Approach 1:
The force distribution is segmented through the stopping member which contacts the flap at a specific location during closure. This concentrates the explosive force transmission through defined paths (flap to stopping member to locking pin to housing), allowing each component to be optimized for its specific load case rather than requiring the entire structure to withstand all forces uniformly
Solution Approach 2:
The locking device is pre-positioned and pre-loaded with the stopping member ready to engage the locking pin. During an explosion event, the mechanism is already in place to immediately absorb and redirect the force, preventing excessive deformation of the flap and housing before the locking action occurs
3Reliability
If the locking pin is biased towards the locking position, then the reliability of flame isolation is improved, but the ease of operation worsens
Solution Approach 1:
The stopping member acts as an intermediary between the flap and the locking pin during the locking action. During normal operation, it allows the locking pin to remain biased in the retracted position. During an explosion, it mediates the force transmission to push the locking pin into the locking position, and during resetting, it mediates the reverse action to release the lock
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Ensures immediate and complete closure of ducting during adverse pressure events, maintaining the flap in a locked position until reset, while withstanding high explosion loads and preventing backdrafts, and allowing for safe operation during fan stand-still conditions.
Implementation Method 1
a locking pin (14) and a stopping member (12), wherein the locking pin (14) is movable between a retracted position and a locking position, and being biased towards said locking position
Implementation Method 2
the stopping member (12) being movable from a stop position in which the stopping member (12) is adapted to hold the locking pin (14) in its retracted position, to a release position by the flap (1) acting on the stopping member (12) in case of a back pressure
Data Source
Figure 1~2
Figure 3~5
Figure 4
AI summary
A back pressure flap valve arrangement is disclosed. The arrangement comprises a housing (101) having an inlet opening (102) and an outlet opening (103) adapted for connection of the housing (101) to a ducting (200), and at least one side wall (104) extending along a flow direction through the housing (101) from the inlet opening (102) to the outlet opening (103). A flap (1) is pivotably hinged about a shaft (5) thereby being movable between an open position and a closed position, said shaft (5) extending transverse the flow direction. At least one locking device (10) is fixedly mounted to the side wall (104) and comprises a locking pin (14) and a stopping member (12). The locking pin (14) is movable between a retracted position and a locking position, and being biased towards said locking position. The stopping member (12) is movable from a stop position in which the stopping member (12) is adapted to hold the locking pin (14) in its retracted position, to a release position by the flap (1) acting on the stopping member (12) in case of a back pressure. Thereby the locking pin (14) is allowed to move into the locking position in which the locking pin (14) maintains the flap (1) in the closed position.