• 한국자동차공학회논문집
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• 제21권6호
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• pp.24-30
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• 2013

This paper studies the comparative analysis on two different internal cushion devices (the types of needle and relief valve) used to absorb the energy which is generated when the pneumatic cylinder moves with the load at meter-out speed control system. The effect at varying the piston velocity under same driving condition is mainly investigated. The simulation results on pressure in the cushion chamber and the dynamic behavior of the relief valve type cushion device are compared with the needle valve type. Design and performance are improved with the cushion configuration of better quality at high-speed pneumatic cylinder. Based on the relation between absorbed energy and impact energy at cushion process, cushion performance at pneumatic cylinder is evaluated.

• 한국자동차공학회논문집
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• 제18권3호
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• pp.95-103
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• 2010

This paper presents a simulation model of a double-acting high-speed pneumatic cylinder with a relief valve type cushion mechanism. The model predicts piston motion, mass flow rate, pressure and temperature time histories of cushion chamber. Of interest here is to investigate the cushioning effect of varying the piston and piston-rod diameter, cushion ring diameter and length, and stoke in cushion mechanism. As a result, this cushion mechanism is found to be adequate under high-speed driving of pneumatic cylinders. The simulation model proposed here will be very useful to analyze the dynamic characteristics and to improve or design the better cushion mechanism in high-speed pneumatic cushion cylinders.

• 드라이브 ㆍ 컨트롤
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• 제13권4호
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• pp.7-13
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• 2016

This paper presents the meter-out and meter-in speed control characteristics of a pneumatic cylinder with relief valve type cushion device. The piston displacement and velocity are measured to investigate high speed driving performance with variation of the pressure setting in relief valve, air supply pressure, load mass, the supply and exhaust flow rate from the cylinder. Also, the internal pressures and temperatures driving pressure and cushion chamber are measured. The piston displacements and velocities of meter-out and meter-in control are compared experimentally determined data. A comparison experimental data meter-out and meter-in control show that a relief valve type cushion device is suitable for high speed pneumatic cylinders. The desired response characteristics of piston displacement and velocity are satisfactory adjust the pressure setting of a relief valve with varying system parameters such as air supply pressure, load mass and controlled flow rate.

• 한국생산제조학회지
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• 제22권1호
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• pp.1-7
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• 2013

Pneumatic cylinders are widely used to actuators in automatic equipments because they are relatively inexpensive, simple to install and maintain, offer robust design and operation, are available in a wide range of standard sizes and design alternatives. This paper presents a comparative study among the dynamic characteristics of meter-out and meter-in speed control of pneumatic cushion cylinders with a relief valve type cushion mechanism. Because of the nonlinear differential equations and a requirement for simultaneous iterative solution in a mathematical model of a double acting pneumatic cushion cylinder, a computer simulation is carried out to investigate pressure, temperature, mass flow rate in cushion chamber and displacement and velocity time histories of piston under various operating conditions. It is found that the piston velocity and pressure response in meter-in speed control are more oscillatory than with meter-out those when pneumatic cushion cylinders are driven at a high-speed. In meter-out speed control, the effective area of the flow control valve is larger than that of meter-in, and the supply pressure has to be much higher than the pressure required to move the load because it has also to overcome the back pressure in cushion chamber.

• 드라이브 ㆍ 컨트롤
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• 제12권4호
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• pp.54-59
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• 2015

Due to the tendency to use high speed pneumatic cylinders to improve productivity, cushioning devices are adopted to decelerate the piston motion of pneumatic cylinders to reduce noise, vibration, and impact. This paper presents a comparison of the cushion characteristics of a high speed pneumatic cylinder with a relief valve type cushioning device. The system parameters selected are the damping coefficient, Coulomb friction, heat transfer coefficient, and cracking pressure of the relief valve in the air cushioning device. The integral of the time multiplied square error (ITSE) is used to quantitative measure the cushioning performance to assess the effect of varying these. The cushioning performance achieved good results when the ITSE is a minimum value. In a comparison of the piston displacement and velocity with the variations in system parameters, the heat transfer coefficients are not as significantly affected as the other. Also, the cracking pressure of the relief valve is mainly affected by the pressure and temperature in the cushion chamber.

• 재활복지공학회논문지
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• 제3권1호
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• pp.49-53
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• 2009

본 논문은 외상성 척수손상 장애인(SCI)과 뇌성마비장애인(CP)의 맞춤형 전동휠체어 적용 시 착석시스템에 대해 비교해 보는 연구이다. 이를 통하여 장애 영역에 따른 맞춤형 전동휠체어 착석시스템의 다른 점을 파악하고, 이러한 결과들을 기초로 하여 휠체어 공적급여 및 처방 시 관련된 문제들을 개선하는데 도움이 되고자 한다. 휠체어 앉기 및 자세는 크게, 자세유지장치, 착석쿠션, 휠체어 자세변환장치 등 세 가지로 구분되어 있다. 국립재활원의 장애인 보조기구 사례관리 시범사업의 2009년 대상자 중 맞춤형 전동휠체어를 처방하고 구축해준 SCI 장애인 5명, CP 장애인 5명을 대상으로 수행한 일련의 과정을 통하여 대상자군에 따라 각 장치의 사용빈도가 차이가 있다는 것을 발견하였다. 자세유지장치는 머리받침대 등 총 10개의 소분류로 구분하였고, 착석쿠션은 공기형 등 총 4개의 소분류로 구분하였다. 휠체어 자세변환장치는 틸팅 등 총 5개의 소분류로 구분하였다. 자세유지장치에서는 대상군에 따라서 각 소분류의 필요 빈도가 달랐으며, 착석쿠션 또한 SCI 장애인은 공기형을 주로 쓰며, CP 장애인은 폼형을 주로 쓰는 것으로 나타났다. 휠체어 자세변형장치로는 SCI 장애인군에서는 다양한 장치를 사용하였으나, CP 장애인군에서는 기본형 전동휠체어 장치를 사용하였다.