• 대한기계학회논문집
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• 제17권12호
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• pp.3179-3186
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• 1993

The study on the spray characteristics of TBI(Throttle Body Injection) injector has been carried out in this paper. The objective of this study is to improve the performance of TBI injector. The increase in the injection pressure and the utilization of assisted air are considered. The spray patten of TBI injector take the hollow-cone shape with $60^{\circ}~70^{\circ}$ spray angle regardless of injection pressure and injection pulse width. SAMD(Sauter Mean Diameter) of water in TBI injector are 510-$550{\mu}m$ and 310-$370{\mu}m$ respectively when injection pressures are $0.75 kgf/cm^{2}$ and $2.8 kgf/cm^{2}$. Then SMD of gasoline is estimated 380~$410{\mu}m$ and 230~$280{\mu}m$ respectively. The improvement of spray characteristics in TBI injector can be obtained with assisted air. If $W_{A}/W_{L}$ was over 0.2, SMD of water can be made under $50{\mu}m$.

• 대한기계학회논문집B
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• 제35권5호
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• pp.517-524
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• 2011

볼텍스 튜브는 고압의 가스를 이용하여 고온 가스와 저온 가스를 분리하거나 입자상 물질의 분리에 사용 할 수 있는 장치이다. 본 연구에서는 직경 10mm의 볼텍스 튜브의 기본 설계 자료를 구축하기 위하여 에너지 분리 성능 실험을 수행하였다. 설계를 위한 기초 자료를 확보하기 위하여, 공급압력, 볼텍스 발생기의 오리피스 직경 및 튜브의 길이가 에너지 분리 특성에 미치는 영향력을 실험을 통하여 분석하였다. 결과적으로 오리피스 직경과 공급압력이 볼텍스 튜브의 성능의 지배적인 성능인자임을 확인하였다. 튜브길이가 성능에 미치는 영향은 미미하였다. Dc=0.7D, L=16D의 볼텍스 튜브에서 가장 우수한 에너지 분리효과를 얻을 수 있었다.

• 한국정밀공학회지
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• 제14권3호
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• pp.156-165
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• 1997

In the practical control systems, the dynamic range of actuatiors is limited(or saturated) when actuators are driven by sufficiently large signals. This gives rise to a nonlinearity as a result of actuator saturation. For example, the upper limit is imposed on productive capability by available factory space and capital equipment. Other examples of those kinds of actuator saturations are a maximum torque of the actua- ting motors and a throttle position in an aircraft speed control A saturating actuator may lead not only to a large overshoot during start-up and shut-down, but also to deterioration of the performance due to the uncertainties. That is, the speed of response is decreased and, possibly, the system output may not follow the lalrge reference inputs. The large-overshoot may be accompanied by rest wind-up(or called by integra- tor wind-up) which comes from controllers with integral action in saturation operation regions. Eventually, as the overshoot increases, the system has a limit cycle or becomes oscillatorily unstable. Due to these cir- cumstances, many studies are focused on the stability and robustness of the nonlinear systems with satu- rating actuator in the time-domain as well as in the frequency-domain.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2000년도 춘계학술대회 논문집(Proceeding of the KOSME 2000 Spring Annual Meeting)
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• pp.45-51
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• 2000

Investigators who study on combustion in the cylinders of reciprocating piston type internal combustion engines have been encountered embarrassments due to the difficulties of adjusting specific parameter without interfacing other parameters such as cylinder wall temperature composition of gas in the cylinder existence of cylinder lubricant etc. Rapid compression-expansion machine the position and speed of piston of which are able to be controlled by means of a system controlled electrically and speed of piston of which are able to be controlled by means of a system controlled electrically and actuated hydraulically could be utilized as one of the most preferable countermeasures against those difficulties. Several units of rapid compression-expansion machines were developed but the speed up of frequency of piston movement still is the problem to be improved to cope with actual speed of internal combustion engines. Authors designed and manufactured a new rapid compression-expansion machine electrically controlled hydraulically actuated and computer programed and then examined the performance of one. Results of a set of experiments revealed acquirements of certain improvement of frequency of piston movement preserving the stability of system response and reproducing accurate compression ratio of cylinder those are the key function for the in-cylinder combustion experiments of internal combustion engines.

• 오토저널
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• 제3권2호
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• pp.18-26
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• 1981

The purpose of this paper is to study the possibility of practical use of gasoline-methanol mixed fuel as an alternative fuel of gasoline engines in the light of engine performances and harmful exhaust emissions as well as mixings and separations of the mixed fuels. When the methanol of 99.8% purity is mixed with super or regular gasoline available on the market today, the experimental results obtained without modifying carburetor in this study are as follows; 1.The separation ratio depends upon the gasoline-methanol mixing ratio only, regardless of fuel temperature and fuel additives for preventing separation of phase. 2.The critical absorption ratio is affected by the gasoline-methanol mixing ratio, its temperature and the quantity of fuel additives. 3.Concerning the distillation temperature, the initial point of all sorts of fuels is almost same,but 10% point and 35-60% point of mixed fuels are lower than those of gasoline only. 4.In case of throttle valve opening set, engine output using the mixed fuels is decreased compared to gasoline, but thermal efficiency is increased as a consequence of decreasing specific energy consumption. 5.In case of fixed load test, thermal efficiency is increased at low engine speed even under low part-load as well as under comparatively high part-load including full load. 6.CO and NOx emissions are reduced remarkably with the mixed fuels.

• 오토저널
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• 제14권5호
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• pp.69-82
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• 1992

Vibration of intake menifold is important as it could worsen the noise levels radiated from surface itself and support bracket, and it eventually leads to the failures of a Throttle Position Sensor and an Idle Air Control Valve. In this study, structural modification method is proposed to reduce structural vibration of an intake manifold system. At first, vibration problems are identified through tests on a running engine. Then modal data acquired by modal testing and finite element analysis are helpful to understand vibration mechanism of the system, and used as the design guide when structural modifications are attempted. After the system model is validated by comparison of the modal data obtained from analysis and experiment, iterative calculations are performed to find optimized structure of the system by finite element analysis. As a result, a newly designed plenum bracket is suggested in such a way that the intake manifold is stiffened, and that design of the support bracket is suggested in such a way that the intake manifold is stiffened, and that design of the support bracket is changed in terms of bolting position, thickness, shape, and minimum weight increase. Finally, it is shown that a new design achieves a significant reduction of vibration of an intake manifold system and it is confirmed by tests on a running engine.

• 오토저널
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• 제14권2호
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• pp.34-43
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• 1992

The purpose of this study is to consider the performance and exhaust characteristics in the practical engine according to the cooling water temperature change of engine and to set up the optimum cooling condition and to obtain the optimum operating condition of thermostat in the cooling system. In order to accomplish the purpose of this study, authors have used the following procedure. 1. This study is to investigate the influence of the cooling water temperature on the engine performance and the exhaust gas, authors regulated the cooling water temperature by using the special closing circuit and measured the concentration of exhaust gas by using the exhaust gas measuring system in the exhaust pipe. 2. This study carried out the experiment by regulating the opening degree of throttle valve and engine speed in the dynamometer and by changing the cooling water temperature, at the same time kept air-fuel ratio constant and made the spark ignition time MBT(Minimum spark advance for Best Torque) 3. This study measured the cooling water temperature by using the K-type thermocouple centring around the easy over-heated parts and by installing a special closing circuit. Therefore, in this study, authors intend to examine the influence of the cooling water temperature on the engine performance, exhaust gas and present the basic materials needed in the engine design including the optimum operating time control system for the cooling water temperature.

• 한국자동차공학회논문집
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• 제25권3호
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• pp.317-325
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• 2017

The EDR(Event Data Recorder) is a part of the ACU(Airbag Control Unit) functions mounted on a vehicle. EDR data have pre-crash data and post-crash data. Pre-crash data are recorded within 5 sec from time zero(AE) with 0.5 sec resolution, and reveal vehicle speed, engine rotation speed, throttle opening, brake pedal operation, acceleration pedal position and steering angle, etc. Using this EDR data, the investigation of a traffic accident can become more objective and scientific. Crash tests of three vehicles equipped with EDR function had been performed successfully. Evaluation of EDR data reliability had also been performed using Vbox and PC-Crash's sequence table function. Based on the results, we could confirm EDR data's reliability and availability for Traffic Accident Analysis by the series of this process.

• Journal of Electrical Engineering and Technology
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• 제10권5호
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• pp.2162-2169
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• 2015

Cruise control is a technology for automatically maintaining a steady speed of vehicle as set by the driver via controlling throttle valve and brake of vehicle. In this paper we investigate cruise controller design method with consideration for distance to vehicle ahead. We employ linear time varying (LTV) model to describe longitudinal vehicle dynamic motion. With this LTV system we approximately model the nonlinear dynamics of vehicle speed by frequent update of the system parameters. In addition we reformulate the LTV system by transforming distance to leading vehicle into variation of system parameters of the model. Note that in conventional control problem formulation this distance is considered as disturbance which should be rejected. Consequently a controller can be designed by pole placement at each instance of parameter update, based on the linear model with the present system parameters. The validity of this design method is examined by simulation study.

• 한국자동차공학회논문집
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• 제7권7호
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• pp.157-166
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• 1999

This paper describes the launching characteristics of a passenger car using a Push-Belt type Continuously Variable Transmission(CVT) which equipped a wet type multi-plate clutch asa starting device and a solid flywheel with a torsional damper for a torsional coupling device. To reduce the torsional vibration of the drive-line , some torsional coupling devices were used for the passenger car equipped CVT having the clutch as a starting device especially . In this study, we developed the computer simulation program to investigate the launching characteristics of a passenger car equipped CVT using the mathematical models of this system. For the mathematical models of the vehicle, the CVT, the we type multi-plate clutch and the torsional damper, we obtained the specification and the necessary data through the reverse engineering of those. For the verification of our analysis, we performed the test of prototype car with different throttle positions at road and dynamometer. The launching characteristics of a passenger car considered here an acceleration performance and an ascending performance.