Threaded-Spindle Friction Damper for Directional Force Control
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Solution Overview
Problem
Existing friction dampers lack a robust and efficient mechanism for variably setting direction-dependent friction forces, which limits their applicability in applications like washing machines and tumble dryers.
Innovation Solution
A friction damper design featuring a housing with a tappet, a friction unit with a threaded spindle for force transmission, and a switching unit with a lockable actuator and locking element, allowing precise control of friction force direction and magnitude through a threaded spindle and self-locking mechanism for failsafe operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a switching unit with a switchable actuator and locking element is used to variably set friction force, then the applicability of the friction damper is improved, but the device complexity increases
Solution Approach 1:
A threaded spindle is introduced as an intermediary force transmission unit between the actuator and locking element. The spindle converts rotational actuator motion into linear locking element displacement, providing precise control while maintaining a compact structure. This mechanical intermediary resolves the contradiction by enabling variable friction force settings without proportionally increasing overall device complexity.
Solution Approach 2:
The friction damper employs a dynamic switching unit that can variably adjust friction force between different states (locked and unlocked positions). The locking element can be positioned at multiple locations along the threaded spindle, allowing the friction force to be changed from minimum to maximum values. This dynamic adjustability improves applicability across different operating conditions while using a relatively simple mechanical structure.
2Measurement precision
If a threaded spindle is used for force transmission to ensure exact positioning, then the positioning precision is improved, but the manufacturing complexity increases
Solution Approach 1:
The threaded spindle provides self-service functionality by automatically converting rotational actuator motion into precise linear positioning of the locking element. The thread geometry inherently provides the positioning precision without requiring additional control mechanisms or complex manufacturing processes. Standard threaded components can be used, reducing manufacturing complexity while maintaining exact positioning capability.
3Ease of operation
If the actuator is configured as single-acting to simplify actuation, then the ease of operation is improved, but the reliability decreases due to inability to actively switch in opposite direction
Solution Approach 1:
The single-acting actuator's limitation (inability to push in both directions) is converted into a benefit through the mechanical design. The actuator only needs to provide force in one direction to move the locking element along the threaded spindle, while spring forces or gravity can assist in returning the mechanism to its initial state. This converts the apparent harm of single-direction actuation into a simpler, more reliable system with fewer active components required.
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 robust, direction-dependent friction force control with reduced energy consumption and failsafe operation, ensuring reliable performance even in power failures, and adaptable for various applications by varying friction force settings.
Implementation Method 1
a force transmission unit which is mechanically coupled to the actuator and to the locking element, wherein the force transmission unit comprises a threaded spindle
Implementation Method 2
the friction unit comprises at least one friction lining that rests frictionally on the tappet
Data Source
AI summary
A friction damper includes a housing having a longitudinal axis, a tappet that is displaceable along the longitudinal axis, a friction unit for generating a direction-dependent friction force on the tappet, wherein the friction unit includes at least one friction lining that rests frictionally on the tappet and a friction lining carrier on which the at least one friction lining is held, wherein the friction lining carrier is arranged to be displaced relative to the tappet between an extraction position and an insertion position, as well as a switching unit for variably setting the friction force, wherein the switching unit includes a switchable actuator, a locking element and a force transmission unit which is mechanically coupled to the actuator and to the locking element, wherein the force transmission unit comprises a threaded spindle.