Switchable Friction Damper for Direction-Dependent Force Control
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Solution Overview
Problem
Existing friction dampers struggle with accurately determining and controlling frictional power, particularly in direction-dependent applications such as washing machines, where the frictional force differs between insertion and extraction directions.
Innovation Solution
The friction damper incorporates a switching unit with a power transmission unit featuring a threaded spindle, which mechanically couples the actuator with a locking element. This setup allows for precise positioning and robust power transmission, enabling active control in both directions and varying the frictional power based on direction and amplitude.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a switching unit with a force transmission unit (threaded spindle) is used to mechanically couple the actuator to the locking element, then the positioning precision and force transmission robustness are improved, but the device complexity increases
Solution Approach 1:
The threaded spindle acts as an intermediary mechanical element between the actuator and the locking element. It converts rotational motion from the actuator into linear displacement of the locking element, enabling precise positioning through the threaded engagement while maintaining a relatively simple overall structure.
2Adaptability or versatility
If the actuator is designed to be double-acting for active switching in opposite directions, then the controllability and adaptability are improved, but the device complexity and energy consumption increase
Solution Approach 1:
The actuator is designed with dynamic capabilities to actively switch between two opposing linear directions. This allows the locking element to be positioned flexibly in different directions along its displacement path, enabling the friction damper to adapt to different operational requirements (insertion vs. extraction) while maintaining a unified actuator structure.
3Productivity
If the friction force is set direction-dependently with variable amounts, then the performance optimization for washing machine operations is improved, but the control system complexity increases
Solution Approach 1:
The friction force is optimized locally for different directional operations. The system applies different friction force characteristics for insertion direction versus extraction direction, allowing each direction to have optimally tuned friction properties suited to its specific functional requirements in the washing machine application.
4Use of energy by moving object
If the threaded spindle is made self-locking to maintain position without continuous actuation, then the energy consumption is reduced, but the positioning precision and adaptability decrease
Solution Approach 1:
The threaded spindle is designed with self-locking capability through its thread geometry, where the friction between mating threads prevents backward movement without requiring continuous actuator engagement. This allows the locking element to maintain its positioned state passively after actuation, significantly reducing energy consumption while preserving sufficient positioning accuracy for the application.
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
This solution allows for precise and variable determination of frictional power, ensuring optimal performance in washing machines by maintaining consistent or adjustable frictional forces depending on the operational direction and load.
Implementation Method 1
The force transmission unit comprises a threaded spindle, which ensures precise positioning of the locking element by means of the switchable actuator
Implementation Method 2
The frictional force is generated by a friction unit in a direction-dependent manner. To generate the frictional force, the friction unit has at least one friction lining that frictionally rests against the plunger
Data Source
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AI summary
A friction damper comprises a housing (2) having a longitudinal axis (3), a plunger (4) displaceable along the longitudinal axis (3), a friction unit (33) for generating a direction-dependent frictional force on the plunger (4), wherein the friction unit (33) comprises at least one friction lining (35) bearing against the plunger (4) and a friction lining carrier (34) on which the at least one friction lining (35) is held, wherein the friction lining carrier (34) is displaceably arranged relative to the plunger (4) between an extension position and an insertion position, and a switching unit (43) for variably setting the frictional force, wherein the switching unit (43) comprises a switchable actuator (44), a locking element (51) and a force transmission unit (47, 48, 50, 52) which is connected to the actuator (44) and to the The locking element (51) is mechanically coupled, wherein the power transmission unit (47, 48, 50, 52) comprises a threaded spindle (50).