• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.7
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• pp.1-7
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• 2014

A variable displacement vane pump is possible to improve the fuel economy by varying the pump capacity with a vane mechanism according to the engine operating speed range and reducing its driving torque. In general the experimental evaluation of the vane pump for the transmission has been performed mainly not with the vehicle or dynamometer test rig but with component test rig due to the implementation and safety problems. In this paper, in order to evaluate the performance of the developed vane pump as well as the compatibility with other rotary and hydraulic components of the target transmission, the transmission dynamometer based test rig is implemented where the developed pump is built into it and then the variable pump capacity and effect of power reduction are investigated experimentally.

• Journal of the Korean Society of Propulsion Engineers
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• v.22 no.3
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• pp.14-20
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• 2018

An estimation law of air mass flow rate for high speed engine control is presented. The variables of mass estimation equations are modified to measurable variables which can be obtained during flight, and the effectiveness of each variable to the estimation accuracy is evaluated. The equation is modified to a simplified form, and the uncertainty is evaluated. In addition, reference data for the selection of estimation methods is suggested by considering the sensitivity analysis of sensor error.

• Transactions of the Korean Society of Automotive Engineers
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• v.9 no.6
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• pp.24-29
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• 2001

Adaptive valve timing control is one of the promising techniques to accomplish the optimized mixture formation and combustion depending on the load and speed, which is needed to meet the future challenges in reducing fuel consumption and exhaust emissions. The behavior and the effect of adaptive valve timing control system has been investigated by computer simulation, which simulates the gas dynamics in engines. Improved fuel economy can be achieved by reduction of pumping loss under low and mid load conditions. EIVC(Early Intake Valve Closing) strategy turns out to be superior to LIVC(Late Intake Valve Closing) strategy in reducing fuel consumption. Deterioration of combustion quality can be overcome by introducing LIVO(Late Intake Valve Opening) strategy, which increases turbulent intensity in cylinders. Furthermore, LIVO can reduce HC emission by decreasing the required amount of fuel to be injected during cold start.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.342-352
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• 2003

Idle NVH characteristics are one of the most important aspects among the vehicle performances. Vehicle developers are devoted to improve vehicle interior noise and steering wheel and seat vibrations. In order to improve the idle quality, noise and vibration transfer path should be carefully evaluated. Also, effects of various components related to the idle performance should be confirmed. A general procedure for improving the idle qualify is described in detail. The relationship among cylinder pressure characteristics, crankshaft rotational speed variation, and vehicle vibrations is also investigated. Influences of drive shaft, torque converter, air conditioning system, vehicle structure including engine mount system, and idle control parameters on the vehicle idle quality are studied. Weak points of typical vehicles on the idle qualify are identified. Some of improvement measures are proposed and verified.

• Journal of Biosystems Engineering
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• v.16 no.2
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• pp.124-132
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• 1991

This study was carried out to obtain the information needed in the development of forward speed control system and the improvement of combine performance. The effects of variety, grain moisture content and forward speed on the combine load characteristics were investigated through experiments. The results of this study are summarized as follows. 1. A data acquisition system was developed to measure the engine speed and the torques and speeds of the threshing cylinder, dean-grain auger and tailings-return auger. The system consisted of transducers, signal conditioner, interface board and microcomputer. The system accuracy is better than ${\pm}2.3%$ full scale. 2. Linear regression equations were obtained for the torque, speed and power requirement of threshing cylinder for different paddy varieties, grain moisture contents and feed rates. 3. The maximum value of relative frequency for threshing cylinder torque decreased as the increase in feed rate and moisture content. The range of torque fluctuation was 1.2~3.7 and 1.2~1.9 times the average and maximum torque, respectively. The maximum value of power spectrum density (PSD) appeared to be about 11 Hz regardless of paddy variety, grain moisture content and feed rate. 4. The speed of tailings return thrower decreased rapidly at below 900rpm, and it fell to near zero about 3 seconds after that time. When the travelling of combine harvester was stopped immediately after sensing the overload, it took about 7 seconds for a full recovery of the no-load speed of tailings return thrower.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.48 no.5
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• pp.241-248
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• 1999

Recently, many linear motion generators and motors are rapidly finding applications that ranges from short stroke linear motion vibrators, such as dynamic cone type loudspeakers to stirling engine driven linear reciprocating alternators, compressors, textile machines etc. The stroke-length may go up to 2m, and the maximum speed is in the range of 5 to 10m/s with oscillating frequency as high as 15 kHz. Therefore, the linear oscillating actuators(LOAs) may be considered as variable speed drivers of precise controller with stoke-length and reversal periods during the reciprocating motion. In this paper, the design, fabrication, experiments, and extraction of control parameters of a moving coil type LOA for driving of linear reciprocating motion control systems, are treated. The actuator consists of the NdFeB permanent magnets with high specific energy as the stator produced magnetic field, a coil-wrapped nonmagnetic hollow rectangular bobbin structure, and an iron core as a pathway for magnetic flux. Actually, the design is accomplished by using FEM analysis for the basic configuration of a magnetic circuit, and characteristic equations for coil design. In order to apply as the drivers of a linear motion reciprocating control system, the control parameters and circuit parameters, such as input voltage-stoke, exciting frequency-stoke, coil inductance and so on, are extracted from the analysis and experiments on concerning a fabricating LOA.

• Transactions of The Korea Fluid Power Systems Society
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• v.5 no.4
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• pp.1-9
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• 2008

In this paper, an energy regeneration algorithm is proposed to make the maximum use of the regenerative braking energy for a parallel hybrid electric vehicle(HEV) equipped with a continuous variable transmission(CVT). The regenerative algorithm is developed by considering the battery state of charge(SOC), vehicle velocity and motor capacity. The hydraulic module consists of a reducing valve and a power unit to supply the front wheel brake pressure according to the control algorithm. In order to evaluate the performance of the regenerative braking algorithm and the hydraulic module, a hardware-in-the-loop simulation (HILS) is performed. In the HILS system, the brake system consists of four wheel brakes and the hydraulic module. Dynamic characteristics of the HEV are simulated using an HEV simulator. In the HEV simulator, each element of the HEV powertrain such as internal combustion engine, motor, battery and CVT is modelled using MATLAB/$Simulink^{(R)}$. In the HILS, a driver operates the brake pedal with his or her foot while the vehicle speed is displayed on the monitor in real time. It is found from the HILS that the regenerative braking algorithm and the hydraulic module suggested in this paper provide a satisfactory braking performance in tracking the driving schedule and maintaining the battery state of charge.