Vacuum Pump Damper Notch Filter Vibration Isolation
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Solution Overview
Problem
Conventional dampers for vacuum pumps face challenges in reducing vibrations on specific frequency bands while maintaining the flexibility of vacuum pump installation postures, as reducing natural frequency can impair stability and lead to resonance issues, especially when the pump is installed upside down or horizontally.
Innovation Solution
A damper system comprising a first vibration absorbing member with a spring element and a mass element, and a second vibration absorbing member with a spring element and damping element, forming a notch filter type vibration isolating structure, where the center frequency is adjusted to coincide with the rotation frequency of the vacuum pump's rotor, using a thin-wall cylindrical member and an elastic member to create a clearance that can be adjusted using spacers or an actuator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the natural frequency of the damper system is reduced to improve vibration isolating properties, then the damping characteristics are improved, but the rigidity of the damper must be decreased which conflicts with the requirement to withstand pressure difference between vacuum and atmosphere
Solution Approach 1:
The damper is divided into two independent vibration absorbing members: a first member (bellows) for absorbing axial vibrations and a second member (elastic material) for absorbing radial vibrations. This segmentation allows each member to be optimized for its specific function without compromising the other, enabling the system to achieve low natural frequency while maintaining sufficient rigidity to withstand pressure differences.
Solution Approach 2:
A hose band is introduced as an intermediary tightening member that applies external force to both the first and second vibration absorbing members. This hose band pre-tensions the bellows and elastic material, enhancing the overall rigidity of the damper system to withstand vacuum pressure while allowing the members to maintain their vibration absorption characteristics.
2Speed
If the damping coefficient of the damper is decreased to reduce natural frequency, then the natural frequency is reduced, but the resonance phenomenon occurs when rotor frequency coincides with natural frequency
Solution Approach 1:
The vibration absorption function is segmented between two members with different characteristics: the bellows provides spring element characteristics for low natural frequency, while the elastic material provides damping element characteristics to suppress resonance. This segmentation allows the system to have low natural frequency without excessive resonance vibrations.
Solution Approach 2:
The damper combines two different materials with complementary properties: a metallic bellows structure for elastic deformation and vibration isolation, and an elastic material (such as rubber or polymer) for damping. This composite structure achieves both low natural frequency and adequate damping to prevent resonance.
3Speed
If the rigidity of the damper is decreased to reduce natural frequency, then the natural frequency is reduced, but the stability of vacuum pump installation postures is impaired
Solution Approach 1:
The damper structure is segmented into axial vibration absorption (bellows) and radial vibration absorption (elastic material), allowing independent optimization. The elastic material provides sufficient radial rigidity to maintain installation stability while the bellows provides low axial natural frequency for vibration isolation.
Solution Approach 2:
The hose band acts as a mediator that applies pre-tension to both vibration absorbing members, enhancing the overall structural rigidity. This pre-tension maintains the damper's stability in various installation postures while allowing the vibration absorption mechanisms to function effectively at low natural frequency.
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 notch filter type vibration isolator effectively reduces vibrations on a particular frequency band, maintaining the flexibility of vacuum pump installation postures and preventing resonance, while ensuring stability and proper operation of the vacuum pump.
Implementation Method 1
a first vibration absorbing member provided with a spring element having a spring constant k and a mass element having a mass m
Implementation Method 2
a spring element having a spring constant k
Implementation Method 3
a damping element having a viscosity damping coefficient C
Implementation Method 4
a mass element having a mass m
Implementation Method 5
a notch filter type vibration isolating structure having a steep damping characteristic in a particular frequency band
Data Source
AI summary
A damper is configured for a vacuum pump that evacuates a vacuum system via gas transfer by a gas transfer mechanism in the vacuum pump by the rotating action of a rotating body in the vacuum pump. The damper restrains the propagation of vibrations produced in the vacuum pump to the vacuum system during an evacuation operation. The damper comprises a vibration absorbing device that is positionable between the vacuum pump and the vacuum system during an evacuation operation and that has a damping characteristic in a frequency band that coincides substantially with a rotation frequency of the rotating body of the vacuum pump.