Power Strut Anisotropic Damping for Directional Friction Torque
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Solution Overview
Problem
Existing damping devices for electromechanical struts provide only a constant torque value in different rotation directions, failing to differentiate torque values based on rotation direction.
Innovation Solution
An anisotropic damping device featuring a shell, a rotatable member, and a torsion spring with a first leg fixedly connected to the shell, where the torsion spring is in interference fit with the rotatable member, and the design includes notches that allow the torsion spring to expand or tighten radially depending on rotation direction, altering friction torque accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a torsion spring with legs fixed to the shell is used to provide damping torque, then damping function is achieved, but only one constant torque value is provided in different rotation directions
Solution Approach 1:
The patent applies asymmetry by making the first notch narrower than the second notch in the shell. This asymmetric notch design causes the torsion spring to experience different interference fit conditions with the shaft in different rotation directions. When rotating in one direction, the spring is compressed radially increasing friction torque; when rotating in the opposite direction, the spring expands radially decreasing friction torque, thus achieving directional torque differentiation without complex additional components
Solution Approach 2:
The patent applies local quality by creating different local geometries in the shell's notches. The first notch has a narrower opening width compared to the second notch, which creates localized different interference fit conditions for the torsion spring. This local geometric variation allows the same torsion spring to generate different friction torques in different rotation directions, resolving the contradiction between adaptability and device complexity
2Adaptability or versatility
If the torsion spring is in interference fit with the shaft to generate friction torque, then damping is provided, but the friction torque cannot be adjusted based on rotation direction
Solution Approach 1:
The asymmetric notch design (first notch narrower than second notch) creates directional dependence in the interference fit between the torsion spring and shaft. During rotation in one direction, the spring is radially compressed increasing interference and friction torque; during rotation in the opposite direction, the spring is radially expanded decreasing interference and friction torque. This asymmetric geometry enables automatic directional friction torque adjustment while maintaining smooth rotation operation
Solution Approach 2:
The patent applies dynamics by allowing the torsion spring to dynamically change its radial interference fit with the shaft during rotation. The spring transitions between compressed and expanded states depending on rotation direction, automatically adjusting the friction torque characteristics. This dynamic adaptation occurs through the asymmetric notch geometry guiding the spring's radial deformation during bidirectional rotation
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 anisotropic damping device generates different torque values in different rotation directions by adjusting the interference fit between the torsion spring and the rotatable member, enhancing the damping mechanism's directional sensitivity.
Implementation Method 1
a friction torque provided by the torsion spring to the rotatable member differs depending on the direction of rotation of the rotatable member relative to the shell
Implementation Method 2
the design includes notches that allow the torsion spring to expand or tighten radially depending on rotation direction, altering friction torque accordingly
Data Source
AI summary
A power strut includes anisotropic damping device that provides different frictional torque on a rotatable member in response to rotation in opposite rotational directions. The anisotropic damping device includes a shell, the rotatable member, and a torsion spring. The shell includes a through hole, and the rotatable member extends through the through hole and is rotatably connected to the shell. The torsion spring is sleeved on the rotatable member and is in interference fit with the rotatable member, and the torsion spring is provided with a first leg fixedly connected to the shell. The rotatable member may include a shaft sleeve fixed to a rotating shaft, with the torsion spring in interference fit with the shaft sleeve.