Pivot Fitting Overload Protection Using Friction Disc Decoupling
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Solution Overview
Problem
Existing pivot fittings for movable furniture parts are prone to damage due to overload, and known overload clutches are expensive and require re-engagement, posing a disadvantage in terms of cost and functionality.
Innovation Solution
A pivot fitting with a clamping mechanism featuring a toothed-ring disc, friction disc, and cone structure that decouples the force-transmitting shaft from the lever in case of overload, allowing for safe pivoting without damage and easy re-engagement when the load is reduced, utilizing a frictionally locking mechanism to define a predetermined torque limit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an overload clutch is mounted between the two levers to prevent damage, then the pivot fitting is protected against overload, but the manufacturing cost increases and the device complexity increases
Solution Approach 1:
The patent employs a friction disc that can be easily replaced after overload events. The friction disc is designed as a simple, inexpensive component that absorbs the overload stress and can be quickly swapped out, avoiding the need for expensive, complex overload clutch mechanisms while maintaining reliable overload protection
Solution Approach 2:
The friction disc is extracted as a separate, standalone component between the toothed-ring disc and the force-transmitting shaft. This separation allows the friction disc to independently handle overload protection without complicating the main lever mechanism, simplifying manufacturing while ensuring reliability
2Reliability
If an overload clutch is mounted between the two levers to prevent damage, then the pivot fitting is protected against overload, but the device complexity increases
Solution Approach 1:
The friction disc serves as a simple sacrificial component that handles overload events. When overloaded, the friction disc slips or wears, providing protection without requiring complex clutch mechanisms. This disposable approach maintains reliability while minimizing device complexity
Solution Approach 2:
The friction disc acts as an intermediary element between the toothed-ring disc and the force-transmitting shaft. It mediates the force transmission, allowing normal operation while providing overload protection through friction-based slip, thereby protecting the main mechanism without adding complexity
3Reliability
If the friction disc is pressed onto the force-transmitting shaft with an interference fit, then the predetermined torque is reliably defined, but the manufacturing precision requirements increase
Solution Approach 1:
The patent uses interference fit as a means to change the friction parameter between the friction disc and the force-transmitting shaft. By controlling the interference fit parameters (such as press fit force or thermal expansion differences), the predetermined torque limit is reliably defined without requiring extremely high manufacturing precision, as the interference fit itself compensates for minor dimensional variations
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 solution provides an inexpensive and effective overload safety mechanism that prevents damage to the pivot fitting and furniture parts, allowing for continuous functionality after an overload event, with adjustable torque limits and a wide range of adjustment angles.
Implementation Method 1
at least one friction disc arranged on the force-transmitting shaft in a rotationally fixed and axially secured manner is pushed onto the toothed-ring disc, wherein the toothed-ring disc is retained on the at least one friction disc in a frictionally locking manner up to a predetermined torque against rotation about the axis of rotation
Implementation Method 2
the at least one friction disc is in pressing contact with the toothed-ring disc on the side of the smaller diameter of the inner circumferential edge of the toothed-ring disc. Due to the cone arranged on the force-transmitting shaft and the friction disc, the friction disc arranged on the force-transmitting shaft in a rotationally fixed manner and the toothed-ring disc are pressed against each other
Data Source
AI summary
A pivot fitting has a first lever mounted such that is pivotable out of a starting position about a force-transmitting shaft serving as an axis of rotation in relation to the shaft. The fitting has a clamping mechanism fixing the first lever in different angular positions relative to the shaft. The clamping mechanism has a toothed-ring disc positioned on the shaft and has an outer toothing structure formed on the outer periphery, a catch mounted in a pivotable manner on the first lever and is loaded in the direction of the outer toothing structure and, in a latching position, is in engagement with the outer toothing structure. A first control disc is mounted in a rotatable manner about the shaft so that following movement through the predetermined angle out of the starting position in an adjustment direction, the catch is disengaged from the outer toothing structure, and with the catch disengaged from the outer toothing structure it is possible for the first lever to be pivoted back relative to the shaft into the starting position.