Radial Vibration Damper Tuning for Modal Separation
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Solution Overview
Problem
Radial vibration dampers for rotating shafts are costly due to complex designs and high production costs, and existing torsional vibration dampers with loose tolerances can shift location, becoming ineffective.
Innovation Solution
A radial vibration damper with an annular channel and a spring damper member having angled surfaces and a specific tuning ratio, allowing for a press-fit installation that decouples the first radial mode from the second axial mode, using a monolithic inertia member and a spring damper with a stiffening rib or wedge-shaped surface, made from cost-effective materials like elastomeric or nylon.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a multi-part inertia member with specially shaped elastomeric member is used to achieve proper radial response and modal separation, then the radial vibration damping performance is improved, but the device complexity and manufacturing cost increase
Solution Approach 1:
The patent merges the multi-part inertia member design into a single monolithic inertia member, eliminating the need for separate components while maintaining the required radial response characteristics and modal separation between first and second modes
Solution Approach 2:
The patent modifies the geometric parameters of the spring damper member, specifically the angle of the interior opposing surfaces of the annular channel (set between 0-45 degrees) and the tuning ratio (clearance gap to selected depth ratio between 1:1.5 to 1:0.5), to achieve proper radial response with simpler construction
2Ease of manufacture
If a torsional vibration damper with radial mode is used to reduce cost, then manufacturing cost decreases, but the axial mode frequency becomes lower than radial mode frequency causing the damper to shift location and become ineffective
Solution Approach 1:
The patent changes the frequency characteristics by adjusting the tuning ratio (clearance gap to selected depth ratio between 1:1.5 to 1:0.5) and the angled surfaces geometry, ensuring the first mode is radial and the second mode is axial with at least 20 Hertz frequency separation, preventing location shift and maintaining effectiveness
3Reliability
If a robust metal-to-metal press-fit is used to secure the damper in position, then the damping effectiveness is improved, but the manufacturing precision requirements increase due to loose tolerances in shaft inner diameter
Solution Approach 1:
The patent uses the tuned parameters (angled surfaces at 0-45 degrees and tuning ratio between 1:1.5 to 1:0.5) to create a press-fit design that accommodates loose shaft tolerances while maintaining secure positioning and damping effectiveness through the spring damper member's compression characteristics
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 a cost-effective radial vibration damper with adequate modal separation, ensuring the first mode is radial and the second mode is axial, with a frequency difference of at least 20 Hertz, maintaining effectiveness and reducing manufacturing costs while ensuring robust installation and operation.
Implementation Method 1
a spring damper member seated in the annular channel... which protrudes therefrom a sufficient distance that, once the shaft-engaging portion is compressed against a shaft, the spring damper member defines a clearance gap
Data Source
Figure 1~2
Figure 3A~3D
Figure 3E
AI summary
Radial vibration dampers have an inertia member (106) defining an annular channel (152) having (i) a radially facing, open face (154); (ii) a bottom surface(156); and (iii) interior, opposing surfaces (158, 159). The interior, opposing surfaces (158, 159) are each angled outward away from a central transverse plane (P) through the inertia member (106) at an angle in a range from zero degrees to at most 45 degrees. A spring damper member (108) is seated in the annular channel (152) to a selected depth that defines a damper gap between a radial inner surface (109) of the spring damper member (108) and the bottom surface (156) of the annular channel (152) and defines a clearance gap between the shaft and the inertia member (106). A tuning ratio of the clearance gap to the selected depth is in a range of about 1:1.5 to about 1:0.5.