Switchable Clutch Friction Brake Eliminates Stick-Slip
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Solution Overview
Problem
Switchable clutches with freewheel experience undesirable rattling noises due to the stick-slip effect, which is exacerbated by temperature dependence and friction torque scattering, leading to unreliable seat height adjustments.
Innovation Solution
Incorporation of an open friction ring acting as a friction brake between the adjusting ring and the housing, with axially curved end sections providing a preload and ensuring precise axial positioning, preventing stick-slip and allowing smooth adjustment without play.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a friction brake is introduced to prevent stick-slip, then adjustment smoothness is improved, but device complexity increases
Solution Approach 1:
The friction ring is nested within the adjusting ring, with the friction ring's end sections positioned inside the adjusting ring's axial space. This nested arrangement allows the friction brake to be integrated into the existing clutch structure without requiring separate mounting space, thereby improving adjustment smoothness while minimizing additional structural complexity.
Solution Approach 2:
The friction ring acts as an intermediary element between the adjusting ring and the housing. It provides the necessary friction brake function to prevent stick-slip effects during adjustment, while its elastic end sections serve as a mediator to maintain continuous contact and ensure smooth operation without directly complicating the main clutch mechanism.
2Measurement precision
If the friction ring is made elastic to provide preload, then positioning precision is improved, but manufacturing precision requirements increase
Solution Approach 1:
The friction ring is designed with elastic end sections that can be deformed during assembly to create a preload force. By changing the physical state of the end sections from relaxed to elastically deformed, the system achieves precise axial positioning of the adjusting ring. The elasticity allows for self-adjustment during assembly, reducing the need for extremely tight manufacturing tolerances while maintaining positioning precision.
3Stability of the object's composition
If the friction brake holds the adjusting ring firmly, then stability is improved, but energy loss increases
Solution Approach 1:
The friction brake applies only the necessary amount of friction force to prevent stick-slip and maintain stable positioning during adjustment. The elastic end sections provide just enough preload to ensure continuous contact and stability without excessive friction that would cause significant energy loss. This partial action approach maintains stability while minimizing energy dissipation.
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 friction brake ensures reliable, play-free operation by maintaining the adjusting ring's position, eliminating stick-slip and allowing seamless rotation without overcoming free travel, even at fluctuating temperatures, thus providing a lossless adjustment experience.
Implementation Method 1
a friction brake acting on the adjusting ring (3), which is designed as an open friction ring (4) acting on the adjusting ring (3)
Implementation Method 2
The end sections directed towards the adjusting ring have a spring-elastic effect, so that they are partially or completely flattened against the bend during assembly, which creates a preload
Data Source
Figure 1~2
AI summary
Switchable clutch with a freewheel, a housing having a clamping surface, a drive element rotatable relative to the housing, an output element rotatable relative to the housing, clamping ramps facing the clamping surface provided on the output element, several clamping rollers arranged between the clamping surface and the clamping ramps, an adjusting ring (3) connected to the drive element and movable along a raceway in the housing, which has contact surfaces for the clamping rollers, wherein the switchable clutch (1) has a friction brake acting on the adjusting ring (3).