• Title/Summary/Keyword: Ratio control valve

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Combustion Characteristics Using a S.I. Optically Acessible Engine with SCV (SCV를 장착학 가솔린 가시화엔진에서의 연소특성)

  • 정구섭;김형준;전충환;장영준
    • Journal of Advanced Marine Engineering and Technology
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    • v.25 no.1
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    • pp.115-123
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    • 2001
  • This study describes the combustion characteristics under various condition of air excess ratio and ignition timing in a 2-valve gasoline optically accessible engine with swirl control valve(SCV). It adapted three different types of SCA(open ration 72.5%, 78%, 89%) to strengthen a swirl flow. Pressure data were acquired using pressure sensor to investigate the effect of swirl flow on combustion, and from these pressure data, IMEP(indicated mean effective pressure) and MFB(mass fraction burnt)were calculated to explain burn rate and flame speed. From acquired flame images, inspected the flame propagation direction, flame area, and flame centroid, Flame propagation direction was shown different tendency between with/without SCV, and flame area with SCV was faster and larger than that of conventional engine. Finally, the representative flame image at each crank angle were acquired by PDF method to verify flame growth process. It is found that strengthened swirl flow is more beneficial for faster and stable combustion.

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Optimal Gas-Flow Conditions for Stabilization of Lean-Burn Combustion (희박연소 안정화를 위한 가스유동장 조건에 관한 연구)

  • 이기형;이창식
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.19 no.3
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    • pp.763-770
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    • 1995
  • Gas flow characteristics within the cylinder is important factors in impoving lean combustion stability. This paper shows the effects of various flow fields generated by a swirl control valve(SCV) on combustion process in a 4-valve spark ignition engine. An impulse swirl/tumble meter was used to elucidation the steady-state flow characteristics, and a rotating grating type LDV was developed to measure the mean velocity and tunbulence intensity in relation to the crank angle. These methodologies were applied to clarify the correlation between gas flow characteristics and combustion stability at a lean air fuel ratio. An analysis of the correlation revealed the gas flow conditions required to optimize a lean-burn system.

A Study on the Modeling of Solenoid Valve for Anti - lock Brake System (미끄럼 방지 제동장치용 솔레노이드 밸브의 모델링에 관한 연구)

  • Song, Chang-Seop;Yang, Hae-Jeong
    • Journal of the Korean Society for Precision Engineering
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    • v.12 no.12
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    • pp.81-90
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    • 1995
  • Anti-lock Brake System has been developed to reduce tendency for wheel lock and improve vehicle control during sudden braking on slippery road surfaces. This is achieved by controlling the braking pressure avoiding wheel lock, while retaining handling and brake performance. This paper is concerned about characteristics of a solenoid valve in hydraulic modulator for controlling brake pressure. First, it was modeling the electromagnet by the permeance method. Second, it was modeling the commercial Maxwell poackage program. And then, a experiment was performed in order to justify modeling. The result of modeling coincided with teh result of experiment and commercial packabe program. As a result, these modelings will be able to use in analysis of dynamic character- istics of the solenoid valve for braking.

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Pressure Ripple Reduction in High Speed On-Off Solenoid Valves Driven by PWM Control (PWM 제어 고속 온-오프 전자밸브에서 발생하는 압력맥동 저감)

  • Kim D.T.;Lee S.K.
    • Transactions of The Korea Fluid Power Systems Society
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    • v.2 no.2
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    • pp.8-13
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    • 2005
  • This paper investigates a fast, accurate and inexpensive hydraulic motor speed control system using high speed on-off solenoid valves. In order to retain the advantages of the two position valve and obtain better performance, the valves are operated by pulse width modulation(PWM) control. PWM signal is generated from a LabWIEW program in microcomputer in order to set up various duty ratio and frequency of carrier wave in PWM signal with varying system parameters. As the results of experiments, the speed control of a hydraulic motor was successfully implemented using on-off solenoid valves. In order to attenuate the pressure ripple and speed variation due to discontinuously controlled flow through the on-off valves, a resonator hose fabricated for automobile power steering system was connected between the valve and a hydraulic motor. From experimental results obtained in the hydraulic motor system with a resonator hose, it was ascertained that the resonator hose showed excellent performances in reducing pressure ripple and motor speed variation.

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Construction of Map for Transient Condition of a Sl Engine and Refinement of Intake Air Model & Fuel Model (가솔린 엔진의 비정상 상태에 대한 Map 구성과 공기 및 연료 모델 개선)

  • 심연섭;강태성;강승표;고상근
    • Transactions of the Korean Society of Automotive Engineers
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    • v.10 no.5
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    • pp.1-8
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    • 2002
  • For gasoline engines, a three-way catalytic converter that has the maximum efficiency at stoichiometric air/fuel ratio is used to clean up the exhaust gas. So a precise air/fuel ratio control is necessary to maximize the catalytic conversion efficiency, For a transient condition, a fred-forward air/fuel ratio control method that estimates the air mass inducted into a cylinder is being used. In this study, a fuel injection map that makes an accurate air/fuel ratio control possible was constructed for the very same transient condition. For the same condition above, intake air model and fuel model were refined so that fuel injection values based on air mass through a throttle valve and intake manifold pressure are equal to the map values.

A Control of CVT Hydraulic System using Embedded System (임베디드 시스템을 이용한 CVT 유압시스템 제어)

  • Han, K.W.;Ryu, W.S.;Jang, I.G.;Jean, J.W.;Kim, H.S.;Hwang, S.H.
    • Transactions of The Korea Fluid Power Systems Society
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    • v.4 no.1
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    • pp.18-24
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    • 2007
  • The continuously variable transmission (CVT) of which speed ratio can change continuously in a fixed range has the benefits of low fuel consumption and exhaust gas because it enables the engine of a vehicle to operate in a high efficiency range regardless of vehicle speed. The speed ratio of belt type CVT is controlled by adjusting line pressure. The one of the line pressure control methods, mechanical-hydraulic control is usually adopting VDT's control method, in which the secondary solenoid valve has two functions both a regulator and a line pressure controller. However, this control method could not show the high performance of CVT with optimal driving capability because of the limitation of simple control algorithm, and it could not gain market share sufficiently in spite of the advantage of CVT with low fuel consumption. On the other hand, the electro-hydraulic control method gives the enhancement of power performance and low fuel consumption by implementing various driving mode using the proportional control or PWM control. The key of CVT technique is to develop a control algorithm of the electro-hydraulic solenoid valve in order to implement the speed ratio efficiently. In this paper, the line pressure control algorithm is proposed and the hydraulic system is controlled using metal belt type CVT test rig and the embedded ECU platform.

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A Study on Exhaust Gas Characteristics and Engine Performance of EGR Valve Installed Engine for Development of EGR Valve Test System (EGR 밸브 평가 장치 개발을 위한 EGR 장착 엔진 성능 및 배출 가스 특성 연구)

  • Na, D.H.;Ko, C.S.;Seo, H.J.;Lee, C.E.
    • Journal of Drive and Control
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    • v.9 no.4
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    • pp.52-57
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    • 2012
  • In this study, in order to understand contents and ranges of design for the EGR Valve test system for improving quality and performance of EGR Valve, engine performance and exhaust gas characteristic of 3L-class diesel engine was analyzed. Experimental operation of engine performance test was performed with 50% engine load and 20% and 100% opening ratio of EGR Valve. From test of performance and exhaust gas characteristic of engine, torque output of engine and temperature and pressure of inlet and outlet of EGR Valve were measured. As a result, for design of EGR Valve test system, input fluid flow of EGR Valve must be set the same amount with exhaust gas flow that was below of engine speed of 2,500 rpm, and temperature of inlet of EGR Valve must be set under about $510^{\circ}C$. And the difference of temperature between inlet and outlet of EGR Valve must be over than about $200^{\circ}C$. Exhaust gas of inlet and outlet of EGR Valve were under 1 bar that was not considerable, and the difference of pressure between inlet and outlet of EGR Valve were under 1 bar that could not effect on mechanical operation of EGR Valve.

Steady-Flow Characteristics and Its Influence on Spray for Direct Injection Diesel Engine

  • Jeon, Chung-hwan;Park, Seung-hwan;Chang, Young-june
    • Journal of Mechanical Science and Technology
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    • v.16 no.7
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    • pp.986-998
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    • 2002
  • Flow and spray characteristics are critical factors that affect the performance and exhaust emissions of a direct injection diesel engine. It is well known that the swirl control system is one of the useful ways to improve the fuel consumption and emission reduction rate in a diesel engine. However, until now there have only been a few studies on the effect of flow on spray. Because of this, the relationship between the flow pattern in the cylinder and its influence on the behavior of the spray is in need of investigation. First, in-cylinder flow distributions for 4-valve cylinder head of DI (Direct Injection) Diesel engine were investigated under steady-state conditions for different SCV (Swirl Control Valve) opening angles using a steady flow rig and 2-D LDV (Laser Doppler Velocimetry). It was found that swirl flow was more dominant than that of tumble in the experimented engine. In addition, the in-cylinder flow was quantified in terms of swirl/tumble ratio and mean flow coefficient. As the SCV opening angle was increased, high swirl ratios more than 3.0 were obtained in the case of SCV -70° and 90°. Second, spray characteristics of the intermittent injection were investigated by a PDA (Phase Doppler Anemometer) system. A Time Dividing Method (TDM) was used to analyze the microscopic spray characteristics. It was found that the atomization characteristics such as velocity and SMD (Sauter Mean Diameter) of the spray were affected by the in-cylinder swirl ratio. As a result, it was concluded that the swirl ratio improves atomization characteristics uniformly.

A Study on the Pressure Surge of ABS Hydraulic System (ABS 유압 장치의 유충 현상에 관한 연구)

  • 김병우;송창섭
    • Transactions of the Korean Society of Automotive Engineers
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    • v.9 no.5
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    • pp.140-147
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    • 2001
  • The solenoid valve in ABS hydraulics, modulator is a two directional on-off valve and is controlled by around 100Hz high speed pulse width modulation. When the inlet valve is switched from open state to closed state, there are braking force degration, noise and vibration due to pressure surge phenomena in the hydraulic line and wheel cylinder. In this study, identifies pressure surge phenomenon in the braking process of a ABS, and investigates the way to reduce the phenomenon. For the purpose theoretical analysis on the pressure surge in the closed state hydraulic line, characteristic curve method based on wave equation was utilized. During this analysis, we could find pressure surge characteristics change due to hydraulic line change and PWM control conditions. In conclusion, by using the results of this study for the pressure surge prediction and reduction method, we could expect braking performance enhancement in Anti-Lock Braking System.

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Design and Dynamic Characteristic Analysis of the Direct Drive-type Pneumatic Servo Valve

  • Kim, Dong-Soo;Lee, Won-Hee
    • 제어로봇시스템학회:학술대회논문집
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    • 2002.10a
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    • pp.88.6-88
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    • 2002
  • In this study, the pneumatic servo valve was developed, and the study results could be summarized as follows; 1. A servo solenoid was designed, and its electromagnetic field was interpreted and the system's transient response was identified by using a commercial analysis program. 2. A program for analysis the flow in the spool was developed, and a study was conducted on the flow rate of the nozzle depending upon the pressure ratio between the upstream pressure and the downstream pressure, when the valve is fully opened in the spool and the flow force depending upon a displacement of the spool in the valve. 3. A PWM analog controller was designed and manufactured in...

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