• Journal of KSNVE
• /
• v.9 no.4
• /
• pp.795-805
• /
• 1999

Rubber mounts so called grommets and pipes are two major paths of vibration transmission from a compressor, an important vibration source in an air conditioner, to the whole unit. A procedure of configuring the suction and discharge pipes of the compressor was developed in this paper so as to reduce the vibration transmission through the pipes as well as the grommets. Through investigating the effects of shapes and connecting disrections of pipe elements on vibration transmission, a guideline to configure the pipe layout, which enables to reduce vibration transmission, was proposed. The initial pipe layout by the guideline was optimized with the objective function, minimization of boty vibration transmission and the cost, and with the constraints to yield the final dimensions of the pipes. The procedure not only minimizes the transmitted force to the circumferential devices but enables to eliminate rubber blocks or dampers, which are generally used to avoid resonances of the pipe system.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.24 no.7
• /
• pp.517-524
• /
• 2014

Micro-vibration induced by on-board equipments such as fly-wheel and cryogenic cooler with mechanical moving parts affects the image quality of high-resolution observation satellite. Micro-vibration isolation system has been widely used for enhancing the pointing performance of observation satellites. In general, the micro-vibration isolation system requires a launch locking mechanism additionally to guarantee the structural safety of mission payloads supported by the isolation system with low stiffness under launch environment. In this study, we propose a passive launch and on-orbit vibration isolation system using shape memory alloy mesh washers for the micro-vibration isolation of spaceborne compressor, which does not require the additional launch locking mechanism. The basic characteristics of the isolator were measured in static and free vibration tests of the isolator, and a simple equivalent model of the isolator was proposed. The effectiveness of the isolator design in a launch environment was demonstrated through sine vibration, random vibration and shock tests.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.40 no.3
• /
• pp.237-242
• /
• 2012

Spaceborne pulse tube-type cryogenic compressors are widely used for space applications. To guarantee cooling performance of the compressor, mission life time and micor-vibration stability, suitable thermal control of compressor is required. Micro-vibration of the compressor is the one of the sources to degrade the pointing performance of observation satellite. In the present work, on-orbit thermal design of compressor in order not to degrade the performance of micro-vibration isolation system keeping the thermal control performance has been proposed and investigated through thermo-mechanical analysis.

• Proceedings of the KSME Conference
• /
• 2001.06b
• /
• pp.618-623
• /
• 2001

In a practical vibration isolation system, vibration is transmitted from the source to the receiver through several paths such as more than one inter-connected point and multi-degree of freedom at each connection point. Therefore, the major path investigation for vibration transmission among them is often required in a point of view of isolation. For the path analysis of multi-dimensional vibration isolation system, it is useful to employ the concept of vibration power in high frequency range where radiation of noise from the receiver structure is concerned. The idea is simple to understand and formulate but rather complicated to apply in practice. For an accurate estimation of power flow especially over a high frequency range, it is well known in theory that rotational motions should be taken into consideration together with translational motions at inter-connected points. In reality, however, power transmissions related to rotational terms are often neglected mainly due to difficulties in the instrumentation. In this paper, necessary formula and measurable mechanical quantities for vibration power analysis will be reviewed and experimental results with rotational terms included for compressor system in a commercial air conditioner will be shown.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2000.11a
• /
• pp.33-48
• /
• 2000

Limitations of the simple single degree of freedom vibration isolation theory in real applications are discussed and a theory of multi-dimensional vibration/noise isolation by power approach is introduced. Illustrations of the application to compressor of an air-conditioner are presented together with problems caused by approximations. Then possible sources of distortions in the vibration power estimation are looked into and some relevant research topics are suggested.

• Journal of KSNVE
• /
• v.2 no.4
• /
• pp.281-292
• /
• 1992

Two types of vibration problems are encountered in industrial field: active isolation and passive isolation. In a passive type of vibration isolation, a foundation of a delicated machinery such as TEM, SEM, inspection- probe test, photolithograph, etc. is designed to have a vibration amplitude lower than an acceptable limit. In an active type, the isolation is focused on the vibration reduction caused by the machine itself(pump, motor, press, compressor, etc.). The foundation for such a machine should be so designed as to reduce the transmitted vibration below the permissible level prescribed. At any case, a transmissibility and stability must to be considered. Since an active isolation type is aimed for a vibration source, it is useful to isolate the transmitted vibrations energy from a major vibration source at the specific location. In this paper, a designed methodology of double anti-vibration system has been examined in order to have low transmissibility and reliable stability. Also experiment of scale model behavior has been conducted. Finally, the experiment output of the transfer function is compared to the analytical data.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2010.05a
• /
• pp.897-898
• /
• 2010

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2002.05a
• /
• pp.627-632
• /
• 2002

The paper considers acoustic analysis of the shock absorbing muffler within a rotary compressor. The internal space of the compressor is modelled as a combination of cavities and pipes. A simple one-dimensional impedance approach is used fur the acoustic analysis in the low frequency range, with ignoring the effects of gas flow and temperature gradients that are closely related to power efficiency of the compressor. Using the similarity between the vibration isolator and the shock absorbing muffler, the source strength transmissibility is newly proposed as a performance measure of the muffler and its validity is supported by power analysis. Some Important muffler design rules obtained are; (1) a muffler cavity and its opening throat should be used as a pair, (2) a long thin throat is desirable for high frequency noise isolation, (3) a large muffler cavity should be used with care since it shortens the working frequency range of the muffler. The rules were applied to redesign a compressor muffler currently in use, and a significant improvement was achieved by simply attaching a throat to the outlet holes of the muffler.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2001.11a
• /
• pp.403-408
• /
• 2001

Structure-borne noise and vibration is one of the main complaints of home appliances such as refrigerators, washing machines, air conditioners, etc. There have been many efforts to reduce the emitting noise and vibration. Mostly the efforts have been concentrated to optimize the mounts shape and its material properties realizing that the vibration power is mainly transmitted to the structure via mounts. It is known that softer mounts have the better vibration isolation effect. But mounts have another important function in addition to the vibration isolation. That is to support the motor and compressor safely. Thus mounts should be stiff enough to resist the supporting items. But the two properties, stiff and soft, are contradict each other. So the designer should compromise the two complicity properties properly in between. Noticing that, motors and compressors themselves are very quite until they are connected to the base structure via mounts, wire connecting idea was proposed in this work. Instead of using conventional mounts, as shown in Fig 4, compressor was mounted using six wires as shown in Fig 5. Since wire is very flexible in bending but stiff in tension, we can realize the ideal mount design requirements, stiff enough to support and soft enough to isolate vibration power. The suggesting idea was tested with an air conditioner outdoor unit.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.15 no.3 s.96
• /
• pp.280-289
• /
• 2005

A single degree of freedom system and transmissibility are key concepts in many problems of vibration isolation. In order to apply this approach, however, several assumptions must be satisfied, which are often not realistic. For examples, in practical systems, vibration transmissions at multi-point with multi-degree of freedom(translational and rotational DOF) take place and mobilities or impedances of receiver structures cannot be ignored any more especially over high frequency range. Therefore, a multi-dimensional treatment is required for accurate estimation of dynamic behavior of the system. In this paper, an approach using vibrational power flow is introduced to deal with analysis of multi-dimensional vibration isolation system in a more practical way and in aspects of vibration isolations and vibration path analysis. Procedures of this approach and some results of research for vibrational power path analysis with rotational terms included are presented. Difficulties in this method are also discussed.