Door Closer Spring Force Adjustment Mechanism
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Solution Overview
Problem
Conventional door closers lack a means to visually adjust and indicate the spring force setting while the door closer housing remains stationary, requiring manual counting of turns or force measurement to determine the spring preload.
Innovation Solution
A spring adjuster and indicator system that includes a non-rotatable spring collar within the door closer housing, allowing linear adjustment of the spring force with a nut and adjusting screw, and a visible tab and markings to indicate the compression level, preventing rotation of the collar and screw during adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a conventional adjusting screw is used to adjust spring force, then the spring force can be adjusted, but the housing must rotate or be disassembled to access the adjustment mechanism
Solution Approach 1:
The adjustment mechanism is segmented from the main housing structure. The adjusting screw and spring collar are separated as independent components that can be accessed through an opening in the housing without rotating or disassembling the entire housing. This allows the adjustment function to be isolated and accessed independently.
Solution Approach 2:
A spring collar is introduced as an intermediary component between the compression spring and the adjusting screw. The collar transmits the adjustment force from the screw to the spring while preventing rotation, serving as a mediator that enables force adjustment without housing rotation.
2Measurement precision
If the spring force setting is adjusted without visual indication, then the adjustment can be made, but the installer cannot verify the spring preload without counting turns or measuring force
Solution Approach 1:
A visual indicator system provides immediate feedback during the adjustment process. The indicator, coupled to the spring collar, displays the spring preload level directly on the housing, allowing the installer to verify the setting in real-time without counting turns or performing separate force measurements.
Solution Approach 2:
The manual verification method (counting turns or measuring force) is replaced with a visual indication system. The indicator translates the mechanical spring collar position into a visible display, substituting complex verification procedures with simple visual observation.
3Manufacturing precision
If the spring collar is allowed to rotate during adjustment, then the adjustment mechanism can be operated, but the spring force cannot be precisely controlled
Solution Approach 1:
The spring collar and adjusting screw feature asymmetric, non-circular cross-sections that mate together. This asymmetric design prevents rotation of the collar on the screw while allowing linear movement along the screw axis, enabling precise axial adjustment without unwanted rotational movement.
Solution Approach 2:
Instead of allowing rotation to drive the adjustment mechanism (as in traditional screw threads), the invention inverts the approach by preventing rotation entirely and using linear axial movement for adjustment. The non-rotatable design inverts the conventional screw mechanism where rotation translates to linear motion.
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
Enables easy visual adjustment and verification of the spring force setting without rotating the door closer housing, allowing precise control of the door closing force while maintaining the housing in a stationary position.
Implementation Method 1
a compression spring (130) biased against the piston (126)... The compression spring (130) urges the piston (126) and rack (138) to the left
Implementation Method 2
a nut (50) threaded on the adjusting screw (34)... rotating the nut (50) serves to move the spring collar (40) longitudinally to adjust the degree of compression
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
An apparatus for adjusting the force in a door operator or closer comprises an elongated housing and a spring therein connected to the door operator or closer. A spring collar is non-rotatable about the longitudinal axis of the housing and adapted to move linearly within the housing. A fixed adjusting screw extends along a longitudinal axis of the housing and the spring collar is slidable linearly along an outer surface of the adjusting screw. A nut is threadably engaged at a distal end of the adjusting screw and is rotatable about the longitudinal axis of the screw, the nut bearing on the spring collar during rotation. The spring collar bears on a distal end of the spring to vary the spring compression and thereby vary force applied by the door operator or closer. The housing has an opening in a sidewall through which the spring is visible, and the housing exterior surface includes markings indicating the degree of spring compression.