Power-Close Door Closer With Adaptive Spring Preload
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Solution Overview
Problem
Existing door closers often fail to meet regulatory requirements for both manual opening force and closing force, as they typically have 50% efficiency, resulting in insufficient closing force to fully close doors, and are costly when upgraded to door operators to meet specific force requirements.
Innovation Solution
A door closer system that includes a force adjustment device, such as a motor, coupled with a spring and damper, which adjusts the pre-load of the spring during opening and closing to meet desired force requirements, allowing for manual opening with reduced force and increased closing force, using a smaller motor to adjust the spring pre-load rather than moving the door itself.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a traditional door closer with spring is used, then the door can close automatically, but the closing force is insufficient to fully close the door
Solution Approach 1:
The door closer system dynamically adjusts the spring pre-load force based on door position and closing phase. The controller modifies the pre-load setting during operation to provide insufficient force during initial closing (allowing manual override) and full force during final closing (ensuring complete closure). This dynamic adjustment resolves the contradiction by making the force characteristic adaptive rather than fixed.
Solution Approach 2:
The system changes the force parameter (spring pre-load) at different stages of door closing. During the closing phase, the controller increases the pre-load setting to provide maximum closing force when needed, while during opening phase it reduces the pre-load to meet accessibility requirements. This parameter change strategy enables the door closer to achieve both insufficient force for manual override and full force for complete closure.
2Force
If the spring pre-load is increased to improve closing force, then the door closes more effectively, but the opening force becomes too high for manual operation
Solution Approach 1:
The door closer dynamically adjusts the spring pre-load based on the operational phase. During closing operation, the system maintains high pre-load to ensure effective door closure. During opening operation, the controller reduces the pre-load to provide acceptable opening force for manual operation. This dynamic adjustment resolves the contradiction by making force high when needed for closing and low when needed for opening.
Solution Approach 2:
The force adjustment operates periodically based on door movement detection. When the door begins to close, the controller activates high pre-load mode. When the door begins to open, the controller switches to low pre-load mode. This periodic switching between force levels allows the system to meet both closing effectiveness and opening ease requirements at different times in the operational cycle.
3Force
If a door operator is used to meet force requirements, then both opening and closing forces can be controlled, but the system becomes costly
Solution Approach 1:
The invention introduces a force adjustment device as an intermediary between the simple spring mechanism and the complex door operator. This intermediary component (motor or actuator) selectively adjusts only the spring pre-load parameter, providing the necessary force control precision at a lower cost than a full door operator system. The intermediary enables precise force control during closing while maintaining cost-effectiveness.
Solution Approach 2:
The system replaces the complex mechanical door operator with a simpler spring mechanism augmented by a force adjustment device. Instead of using a motor-driven door operator to directly move the door, the invention uses a motor or actuator to adjust spring pre-load, leveraging the spring's mechanical energy for door movement. This substitution achieves comparable force control precision at reduced system cost and complexity.
4Ease of operation
If the spring pre-load is decreased to ease manual opening, then the door opens more easily, but the closing force becomes insufficient
Solution Approach 1:
The door closer dynamically adjusts the spring pre-load based on operational phase. During opening operation, the system maintains low pre-load to ensure easy manual opening. During closing operation, the controller increases the pre-load to provide sufficient closing force for complete door closure. This dynamic adjustment resolves the contradiction by making force low when needed for opening and high when needed for closing.
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
The system ensures doors meet ADA and fire safety codes by adjusting the pre-load to maintain opening forces under 5 lbs. and increasing closing forces as needed, reducing costs compared to door operators while maintaining operational efficiency.
Implementation Method 1
A door closer may include a closing device, such as a spring, that is able to provide a closing force on the door
Implementation Method 2
A door closer may include a closing device, such as a spring, that is able to provide a closing force on the door. The door closer may also include a damper, such as a hydraulic damper, that is able to control a closing speed of the door
Data Source
AI summary
A door closer may utilize a door closing device (e.g., spring) and a force adjustment device (e.g., a motor) in order to allow for manual door opening and assisted door closing. During operation, as a door is manually opened, the spring is loaded (e.g., compressed or tensioned) above its pre-loaded closed position state. Once manual opening is completed, the spring that is loaded during opening begins returning to the pre-loaded closed position state, and thus, moves the door automatically towards the closed position. Depending on the pre-loaded spring setting, the closing force of the door may not be enough to close the door, or to close the door with the preferred force. As such, during closing a controller may engage a motor not to drive the door directly, but to increase the pre-load of spring to increase the closing force in order to allow the door to close as preferred.