Pivot Fitting With Friction-Disc Overload Protection for Furniture
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Solution Overview
Problem
Existing swivel fittings for movable furniture parts are prone to damage due to overload, and known overload clutch solutions are expensive and require re-engagement in an offset pattern.
Innovation Solution
A swivel fitting with a clamping mechanism featuring a toothed ring disk, a pawl, and a friction disc that decouples the power shaft from the lever in case of overload, allowing the lever to pivot without damaging the mechanism, and re-engages when the overload is reduced.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an overload clutch is mounted between the two levers to protect against overload, then the swivel fitting is protected against damage, but the manufacturing cost increases and the clutch requires re-engagement in an offset pattern
Solution Approach 1:
The invention extracts the overload protection function from a complex integrated clutch mechanism and implements it through a simple friction disc that can slide axially on the power shaft. This separates the overload protection function from the clamping mechanism, allowing the friction disc to independently engage and disengage based on torque conditions without requiring complex re-engagement patterns.
Solution Approach 2:
The invention changes the operational parameter from mechanical tooth engagement (in traditional clutches) to friction-based torque transmission. The friction disc creates a predetermined torque limit through friction forces, and when exceeded, the friction disc slides axially to decouple the toothed ring disk from the power shaft. This parameter change simplifies the structure while maintaining reliable overload protection.
2Reliability
If a traditional overload clutch is used, then overload damage is prevented, but the manufacturing cost is relatively expensive
Solution Approach 1:
The invention replaces expensive traditional clutch components with a simple friction disc made from inexpensive materials. The friction disc is designed as a simple cylindrical component with axial sliding capability, eliminating the need for complex clutch mechanisms. This disposable-like approach uses a simple, replaceable component that provides reliable overload protection at minimal manufacturing cost.
3Force
If the friction disc is pressed onto the power shaft with a press fit, then sufficient friction torque is achieved, but assembly complexity increases
Solution Approach 1:
The invention merges the mounting function into the power shaft itself by integrating a conical mounting surface directly onto the shaft. The friction disc is pressed onto this conical surface, combining the mounting and friction torque generation functions into a single integrated structure. This eliminates separate mounting components and simplifies the assembly process while maintaining sufficient friction torque.
Solution Approach 2:
The invention uses an asymmetric conical mounting surface on the power shaft instead of a symmetric cylindrical interface. The conical geometry creates a self-centering effect and provides axial pressing capability that simplifies assembly. The asymmetric shape allows the friction disc to be easily pressed into position and maintains constant radial pressing force during rotation, achieving sufficient friction torque without complex assembly procedures.
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
Provides cost-effective overload protection that allows the swivel fitting to function fully after an overload event, with a maximum adjustment angle of approximately 250° and a predetermined torque limit to prevent damage.
Implementation Method 1
The resilient pressure force of the friction disk creates friction on the cone and on the contact surface of the toothed ring disk.
Data Source
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AI summary
A pivot fitting, in particular for movable furniture parts on pieces of upholstered furniture, has at least one first lever (2), which is mounted such that it can be pivoted out of a starting position through a predetermined angle about a force-transmitting shaft (6) serving as an axis of rotation (D) in relation to said shaft, and has a clamping mechanism, by means of which the first lever (2) can be fixed in different angular positions within the predetermined angle relative to the force-transmitting shaft (6), the clamping mechanism having a toothed-ring disc (4, 202, 302), which is positioned on the force-transmitting shaft (6) and has an outer toothing structure (41, 222, 322) formed on the outer periphery, having a catch (5), which is mounted in a pivotable manner on the first lever (2), is loaded in the direction of the outer toothing structure (41, 222, 322) and, in a latching position, is in engagement with the outer toothing structure (41, 222, 322), and having a first control disc (7, 201, 301), which is mounted in a rotatable manner about the force-transmitting shaft (6) and by means of which, following movement through the predetermined angle out of the starting position in an adjustment direction (V), the catch (5) can be disengaged from the outer toothing structure (41, 222, 322), and therefore, with the catch (5) disengaged from the outer toothing structure (41, 222, 322), it is possible, by movement through the predetermined angle (a) in a return direction (R), for the first lever (2) to be pivoted back relative to the force-transmitting shaft (6) into the starting position, wherein at least one friction disc (8, 203, 303, 304) is pushed onto the toothed-ring disc (4, 202, 302), said friction disc being arranged in an axially and rotationally secured manner on the force-transmitting shaft (6), wherein the toothed-ring disc (4, 202, 302) is retained in a frictionally fitting manner on the at least one friction disc (8, 203, 303, 304) such that, up to a predetermined torque (M), it cannot rotate about the axis of rotation (D). A description is also given of a piece of furniture (100).