Vacuum Pump Sound Muffling Device Using Nested Expansion Chamber
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Solution Overview
Problem
Conventional vacuum pumps with sound muffling devices face challenges in downsizing while maintaining effective sound muffling, as reducing the size of the muffling device alone does not provide the desired sound reduction.
Innovation Solution
A vacuum pump design incorporating a sound muffling device with a casing, first and second passage portions, and a valve chamber, which introduces and discharges gas through an expansion chamber to reduce exhaust sound, and includes a compact configuration to secure sound muffling effect and downsizing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the sound muffling device is downsized, then the vacuum pump can be reduced in size, but the sound muffling effect deteriorates
Solution Approach 1:
The sound muffling device is nested within the housing structure of the vacuum pump, with the expansion chamber utilizing the space between the housing outer wall and the sound muffling device inner wall. This nesting approach allows the sound muffling function to be integrated into the existing pump structure without significantly increasing the overall pump volume, thereby achieving both downsizing and effective sound reduction.
Solution Approach 2:
The expansion chamber is designed to extend in the axial direction of the rotor, utilizing the length dimension rather than increasing radial or lateral dimensions. This dimensional strategy allows the expansion chamber to achieve sufficient volume for effective sound muffling while keeping the pump's footprint compact, resolving the contradiction between size reduction and sound muffling performance.
2Object-affected harmful factors
If the cross-sectional area of the expansion chamber is increased to improve sound muffling, then the sound reduction effect is improved, but the device size increases
Solution Approach 1:
The expansion chamber utilizes the axial length of the rotor as its primary dimension, extending along the rotor axis rather than expanding radially. This allows the chamber to achieve sufficient volume for effective sound muffling while maintaining a compact radial profile, thereby improving sound reduction without significantly increasing the overall device size.
Solution Approach 2:
The sound muffling device is positioned locally within the housing, with the expansion chamber strategically located to utilize available space between the housing outer wall and the device inner wall. This localized placement optimizes the use of available volume for sound muffling purposes without requiring a proportional increase in overall device dimensions.
3Reliability
If a valve member is added to prevent counterflow, then gas backflow is inhibited, but the device complexity increases
Solution Approach 1:
The valve member is integrated into the existing exhaust port structure, combining the valve function with the exhaust passage. The valve chamber is formed within the sound muffling device housing, merging multiple functions (sound muffling, gas flow control, and exhaust) into a single integrated component, thereby reducing overall device complexity while maintaining reliable counterflow prevention.
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 design achieves a significant sound muffling effect and allows for the downsizing of vacuum pumps by utilizing a compact sound muffling device that secures the capacity of the expansion chamber and inhibits counterflow, improving sound reduction in low-frequency bands.
Implementation Method 1
the sound muffling device causes the gas discharged from the exhaust port to pass through the first passage portion, the expansion chamber, and the second passage portion to be discharged, to thereby reduce pump exhaust sound at a predetermined level or less
Data Source
AI summary
A vacuum pump includes a pump main body and a sound muffling device. The pump main body includes a housing including an intake port and an exhaust port, and a rotor that is rotatably arranged inside the housing and transports gas from the intake port to the exhaust port. The sound muffling device includes a casing, a first passage portion, and a second passage portion. The casing includes an opening end portion that is airtightly connected to an outer wall surface of the housing, a bottom wall portion that faces the opening end portion, and a peripheral wall portion, the casing defining an expansion chamber by the outer wall surface of the housing and respective inner wall surfaces of the bottom wall portion and the peripheral wall portion.