• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2004년도 유체기계 연구개발 발표회 논문집
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• pp.697-702
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• 2004

LG Electronics developed linear compressors for a household refrigerator which can reduce energy consumption up to $24\%$ by only Drop-ln instead of a conventional reciprocating compressor. The linear compressor is composed of a linear oscillating motor, a piston directly coupled with the linear motor, a cylinder and the specific discharge system of LG. Because of this free-piston structure, the position of the piston can be changeable according to the voltage variation, load variation and so on. By this reason, LG linear compressor has been in need of an additional unit to control the position of the free-piston stably. In this paper we will introduce the innovative technology which is able to operate the linear compressor without controlling the piston position like a conventional reciprocating compressor.

• Tribology and Lubricants
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• 제17권2호
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• pp.138-145
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• 2001

The rolling piston type rotary compressor has been widely used for refrigeration and air-conditioning systems due to its compactness and high-speed operation. The present analysis is a part of research program directed toward maximizing these advantages of refrigerant compressors. The study of lubrication characteristics in the critical sliding component is essential for the design of refrigerant compressors. Therefore, theoretical investigation of the lubrication characteristics of a rotary compressor used for refrigeration and air-conditioning systems is studied. Newton-Raphson method is used for the partial elastohydrodynamic lubrication analysis between vane and rolling piston in the rotary compressor. The results show that the rotational speed of a shaft and the discharge pressure influence significantly the friction force and the energy loss between vane and rolling piston.

• 한국정밀공학회지
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• 제20권6호
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• pp.205-213
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• 2003

This paper is concerned with a roiling piston type rotary compressor for air conditioning use. Vibration of the compressor is analyzed numerically and experimentally. Multibody dynamic analysis methods to predict the vibration is given. The compressor is modeled as a system composed of bodies, joints, and force elements. Experimental results are also shown to be compared with simulation results. A sensitivity study using different variables that affect the compressor vibration is also carried out. It is found that the mass of weight balancer plays an important role in acceleration.

• 한국정밀공학회지
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• 제17권8호
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• pp.53-59
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• 2000

In this study aluminum casting experiments are carried out to reduce the grain size of a cast preform and to spheriodize its dendritic structure by adding Ti+B and Zr and to modify flaked eutectic silicon by adding Sr, And a finite element simulation is performed to determine an optimal configuration of the cast preform to be used in forging of a compressor piston for an automobile air-conditioner. When 0.15% Ti+B Zr and 0.05% Sr are added respectively into the molten aluminum alloy the finest grain in casting of the preform is obtained. It is confirmed that the optimal configuration of the cast preform predicted by FEM simulation is very useful for forging the compressor piston. After forging the cast preform of the compressor piston. the microstructure and the hardness of the cast preform is compared with those of the cast/forged product.

• 설비공학논문집
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• 제17권8호
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• pp.754-763
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• 2005

This paper introduces a new concept compressor in which piston orbits in the cylinder having an annular space formed between two concentric circular walls. In this configuration, two gas pockets are formed with $180^{\circ}$ phase difference: one between the wrap of the orbiting piston and the inner cylinder wall and the other between the piston wrap and the outer cylinder wall. This alternating feature of gas compression and discharge processes yields several advantages such as low torque variation and low gas pulsation. Computer simulation program has been developed to evaluate the compressor performance. The volumetric, adiabatic, and mechanical efficiencies of the orbiter compressor are calculated to be $85.6\%,\;97.2\%,\;and\;95.2\%$, respectively, when it is used as an air compressor.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2002년도 proceedings of the second asia international conference on tribology
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• pp.411-412
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• 2002

Piston-cylinder system are widely used in power engineering applications. In reciprocating refrigeration compressors, where extremely low friction losses are required, ringless pistons are being used to diminish the friction between piston rings and cylinder wall. Since the ringless piston has the freedom of lateral motion there is a potential danger that it will occasionally hit the cylinder wall while moving up and down along it's axis. A good design must therefore provide a smooth and stable reciprocating motion of the piston and ensure that the fluid film separating the piston from the cylinder wall is maintained all times. And the compromise between refrigerant gas leakage through the piston-cylinder clearance and the friction losses is required utilizing a dynamic analysis of the secondary motion for the high efficiency compressor. To this end, the computer program is developed for calculating the entire piston trajectory and the lubrication characteristics as functions of crank angle under compressor running conditions. The results explored the effects of some design parameters and operating conditions on the stability of the piston, the oil leakage, and friction losses.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 1996년도 제23회 학술대회
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• pp.7-16
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• 1996

Rapid increase of refrigeration & air-conditioning system( r & a system ) in modern industries brings attention to the urgency of development as a core technology in the area. And it required to the compatibility problem of r & a system to alternative refrigerant for the protection of environment. Then, it is requested to research about the lubrication characteristics of refrigerant compressor which is the core thechnology in the r & a system. The study of lubrication characteristics in the critical sliding component is essential for the design of refrigerant compressor. Therefore, theoetical investigation of the lubrication characteristics of rotary compressor for r & a system is studied. And the Runge-Kutta method is used for the analysis of the behavior of rolling piston in the rotary compressor. The results show that the rotating speed of shaft and the discharge pressure have an important effect upon the angular velocity of the rolling piston. This results give important basic data for the further lubrication analysis and design of the rotary compressor.

• Journal of Power Electronics
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• 제6권1호
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• pp.29-37
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• 2006

A sensorless control for an IPM (Interior Permanent Magnet) synchronous motor in a single piston rotary compressor is presented in this study. The rotor position is estimated from the d-axis and q-axis current errors between the real system and a motor model of the position estimator. The torque pulsation of the single piston rotary compressor is compensated to reduce speed ripples, as well as, mechanical noise and vibration. The proposed sensorless drive enables the compressor to operate at a lower speed which increases energy savings and reduces mechanical noise. It also gives high speed operations by a flux weakening control for rapid air-cooling and heating of the heat pump air-conditioners.

• Tribology and Lubricants
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• 제17권1호
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• pp.22-27
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• 2001

This paper presents an analysis of eccentricity ratio of rolling piston using mobility method which is a powerful tool for analyzing dynamically-loaded journal bearings with efficiency and applicability. And, we investigate influences of design parameters (discharge pressure, radial clearance, rotational velocity of shaft, and eccentricity of compressor) on bearing load and eccentricity ratio. The results show that the discharge pressure, radial clearance and rotational velocity of shaft have significant influence on eccentricity ratio, and the discharge pressure and eccentricity of compressor have influence on bearing load.

• 소음진동
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• 제10권4호
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• pp.615-622
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• 2000

Discharge valve mechanism for an electrodynamic-oscillating compressor is different from that of a conventional reciprocating compressor. It has a larger discharge port area, heavier valve mass and stiffer valve spring comparing with the reciprocating one. Since the motion of piston is not kinematically restricted as in conventional reciprocating compressors, the stroke of the piston can change sensitively with supplied boltage and load. Thus piston can impact with discharge valve occasionally. This work deals on dynamic analysis of discharge valve considering all of those different characteristics. Impact is considered by a spring-mass model, and the pressure fluctuation at the both sides of the valve is also included considering the discharge port area and valve spring preload. It is assumed that piston moves in the region of between top and bottom dead center not by calculating piston motion from an electrodynamic equation but by getting values through experiment. Discharge pressure fluctuation is calculated using Helmholtz modeling. Finally, dynamic model for a discharge valve is constructed. In order to validate the model analysis results, the valve motion is experimentally measured and compared with analysis.