Vibration Isolator Dimensioning Using Negative Rigidity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Vibration isolators used in semiconductor lithography, particularly in vacuum chambers, face challenges in minimizing volume while maintaining low-frequency tuning, leading to increased installation space and complexity due to the rigidity of bellows and the need for additional external volumes.
Innovation Solution
A method for dimensioning vibration isolators that accounts for negative stiffness, combining the smallest piston area with the highest proportion of negative rigidity to minimize volume, eliminating the need for additional external volumes by optimizing the working space and incorporating means like magnets and rotary joints to adjust stiffness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the volume of the vibration isolator is minimized, then installation space within the vacuum chamber is reduced, but the ability to achieve low-frequency tuning is compromised
Solution Approach 1:
The patent applies parameter changes by systematically varying the piston area and fluid volume parameters to achieve the optimal balance between compact size and low-frequency tuning. The dimensioning method calculates specific parameter values (piston area A, fluid volume V) that satisfy both the volume minimization goal and the natural frequency requirement f0 = (1/2π)√(k/m), where k is the stiffness determined by the parameters.
2Strength
If bellows are used to close the working space, then structural integrity is improved, but horizontal rigidity increases making the system too stiff
Solution Approach 1:
The patent employs flexible membranes instead of rigid bellows to close the working space. These flexible membranes provide the necessary structural integrity to contain the fluid while simultaneously maintaining low horizontal rigidity, allowing the isolator to remain compliant in the horizontal direction while preserving vertical support capabilities.
3Manufacturing precision
If additional external volume is connected to the working space, then low-frequency tuning is achieved, but device complexity and vacuum feedthrough requirements increase
Solution Approach 1:
The patent merges the functions of the working space and the compliance volume into a single integrated fluid volume contained within the isolator housing. This eliminates the need for separate external volume chambers and complex vacuum feedthroughs, while still achieving the required low-frequency tuning through proper dimensioning of the combined volume.
4Volume of moving object
If piston area is reduced to minimize volume, then compactness is improved, but the force required to support the load increases
Solution Approach 1:
The patent uses parameter changes by calculating the optimal piston area A that balances the competing requirements of compactness and force distribution. The dimensioning method determines A such that the pressure distribution across the piston surface provides adequate support force for the load m while maintaining a compact overall volume, based on the relationship between pressure, area, and the natural frequency requirement.
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 approach results in a compact vibration isolation system with reduced volume, minimizing installation space within vacuum chambers and reducing the complexity of vacuum feedthroughs, while maintaining effective low-frequency tuning.
Implementation Method 1
The working space includes a fluid volume, via which a piston is supported in a horizontal and a vertical direction in a vibration-isolated manner
Implementation Method 2
Patent specification EP 1 359 341 B1 (Integrated Dynamics Engineering GmbH) shows a magnetic spring device with negative rigidity, in which a module made of permanent magnets adds negative rigidity to the overall system of the vibration isolator
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The method involves oscillation-isolatingly supporting a piston in horizontal and vertical directions. A negative rigidity of a negatively rigidity adding unit (9) of an oscillation isolator (1) is considered during calculation of a volume of a working chamber (3), where the volume is required for a desired natural frequency of the isolator. The isolator is dimensioned for three, preferably six degrees of freedom. The volume of the chamber is minimized during dimensioning. A sum of a positive rigidity and the negative rigidity is formed during calculation of the degrees of freedom. Independent claims are also included for the following: (1) an oscillation isolator (2) a stationary oscillation isolation system (3) an arrangement.