Door Actuator Linkage with Fusible Detachment for Fire Safety
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Solution Overview
Problem
Existing door actuators, particularly in fire protection doors, fail to completely detach from their assembly surfaces during a fire, posing a risk of continued proximity to heat sources due to residual linkage attachment.
Innovation Solution
A linkage system for door actuators that includes a hinge and lever arrangement, designed to detach through the weight of the actuator falling or via thermally activatable trigger elements, ensuring complete separation from the assembly surface during a fire.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the door actuator is fastened to the assembly surface with fusible screws, then the door actuator can detach in the event of a fire, but the linkage may remain attached and keep the actuator too close to the heating door
Solution Approach 1:
The linkage is divided into multiple detachable connection points: the fastening arrangement with fusible screws connecting the hinge to the assembly surface, and the securing element connecting the lever arrangement to the hinge. This segmentation ensures that if one connection remains intact, another can detach to allow complete separation and prevent heat exposure.
Solution Approach 2:
The fusible screws are pre-positioned in the fastening arrangement to automatically detach the linkage at a predetermined temperature threshold. This preliminary preparation ensures that no manual intervention is needed during a fire emergency, and the detachment occurs automatically when thermal conditions warrant it.
2Stability of the object's composition
If the linkage uses secure fastening arrangements, then the door actuator remains reliably attached during normal operation, but the linkage cannot detach completely in the event of a fire
Solution Approach 1:
Different parts of the fastening system have different thermal properties: the fusible screws are made of material that melts at a specific temperature, while other components like the hinge and lever arrangement use heat-resistant materials. This local differentiation allows the system to maintain stability during normal operation but detach selectively during fire conditions.
Solution Approach 2:
The fastening system transitions from a stable attached state to a detached state through parameter change - specifically, the fusible screws change their mechanical properties (strength, melting point) in response to temperature changes. This allows the same component to provide secure attachment during normal operation and automatic detachment during fire emergencies.
3Reliability
If the linkage includes thermally activatable trigger elements, then complete detachment is achieved in fire scenarios, but the device complexity increases
Solution Approach 1:
The triggering function is merged with the existing fastening screws rather than being a separate mechanism. The fusible screws serve dual purposes: they provide the primary fastening function during normal operation and simultaneously serve as the thermal trigger for detachment. This merging eliminates the need for separate trigger mechanisms and reduces overall system complexity.
Solution Approach 2:
The fusible screws are self-activating trigger elements that automatically respond to thermal conditions without external control. When exposed to fire heat, the screws naturally melt and detach the linkage themselves, eliminating the need for external sensors, actuators, or control systems. This self-service approach simplifies the overall device complexity while maintaining reliable fire safety functionality.
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 the door actuator fully detaches from its assembly surface, preventing further heat exposure and enhancing safety in fire scenarios.
Implementation Method 1
If these fusible screws heat up in the event of a fire, the door actuator can fall off its assembly surface
Implementation Method 2
The lever arrangement is fastened to the hinge, in particular to the hinge pin, so as to be rotatable about the hinge axis perpendicular to the assembly axis
Implementation Method 3
the door actuator then continues to hang on its linkage and may therefore be too close to the door that is heating up
Data Source
AI summary
A linkage for force transmission between a driven axle of a door actuator and an assembly surface, includes a hinge, a fastening arrangement designed for fastening the hinge to the assembly surface, in particular a door, frame or wall, wherein an assembly axis is defined perpendicularly to the assembly surface, and a lever arrangement which is fastened to the hinge so as to be rotatable about a hinge axis perpendicular to the assembly axis and which is designed for rotationally-fixed connection to the driven axle of the door actuator. The linkage is designed to detach through the weight of the door actuator falling down in the event of a fire and/or wherein the linkage includes a thermally activatable trigger element that is designed to detach the linkage in the event of thermal activation triggered by a fire.