• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.8 no.2
• /
• pp.185-188
• /
• 2007

Lately, the modulated EGR system that includes EGR valve and EGR cooler is being installed in diesel engines fur the purpose of the simultaneous reduction of NOx and PM. In this study. we designed and constructed a test bench for the performance evaluation of the modulated EGR system, and tested an electronically controlled EGR valve for 2.0 L diesel engines. The performance of the EGR valve was evaluated in terms of the valve lift behavior. the valve opening/closing response, and the mass flow rate through the valve. The valve lift with respect to the duty ratio of PWM signal was non-linear, and followed a different path fur valve opening and closing, that is, hysteresis. The valve opening response was concluded satisfactory falling within the usual standard response time. For the duty ratio of 40 to 60%, the mass flow rate through the valve was observed to depend on the pressure difference across the valve as well as the duty ratio, while it solely depended on the pressure difference fur the duty ratio above 60%.

• Proceedings of the KSME Conference
• /
• 2001.06d
• /
• pp.933-938
• /
• 2001

A 5-valve(intake 3-valve) engine has been developed to increase engine performance. These vehicles have a high power caused by the decrease of inertia mass of an intake valve and the increase of intake effective area. In this study, velocity profiles at near intake valves were inspected by using a two-color PIV and laser sheet method with tumble control valve(TCV). In addition, steady flow tests were performed to quantify tumble ratio on flow-fields generated with a TCV. These experimental results show that the tendency of the tunble ratio in intake 3-valve engine is different from the one in intake 2-valve engine. From this results, the intake flow characteristics around intake valves were made clear.

• Proceedings of the KSME Conference
• /
• 2001.06b
• /
• pp.676-681
• /
• 2001

ABS is a safety device, which adds hydraulic system to the existing brake system to prevent wheel from locking, so we can obtain maximum braking force on driving. The hydraulic system to control braking pressure consists of sol-flow type using solenoid valve, flow control valve or consists of sol-sol type using two solenoid valve. In this paper, the hydraulic system in ABS is composed of sol type using a 3port-2position solenoid valve, and vehicle system is composed of 1/4 vehicle model. And slip ratio is controlled using PWM (Pulse-Width-Modulation) control algorithm. Braking friction coefficient and tracking friction coefficient which are described by slip ratio's function have maximum value when slip ratio has its value from 0.1 to 0.3. And slip ratio is controlled constantly in this boundary value even in the variation of road's condition in some boundary.

• Transactions of the Korean hydrogen and new energy society
• /
• v.18 no.3
• /
• pp.348-355
• /
• 2007

To grasp a feasibility of back fire control by valve overlap period, back fire limit equivalence ratio was estimated with valve overlap period which has the same supply energy and positive intake pressure as valve overlap period $300^{\circ}\;CA$. As the result, it was shown that the smaller valve overlap period has the higher back fire limit equivalence ratio under valve overlap period $300^{\circ}\;CA$ as well as VOP $0^{\circ}\;CA$. This result means that expansion of back fire equivalence ratio by decreasing valve overlap period was caused by decrease of back flow duration of flame from in-cylinder to intake port than decrease of lower supply energy.

• Journal of ILASS-Korea
• /
• v.1 no.2
• /
• pp.50-56
• /
• 1996

In an fuel injection type gasoline engine, atomization of fuel droplet and mixture formation process are very important to understand engine combustion efficiency, and also has influence directly on the decision of engine performance and pollutant emission. In this study, perforated throttle valve instead of solid type throttle valve was developed and equipped to an SPI engine to promote secondary atomization and good droplet-air mixture formation. From the engine performance lest. it was verified that the case of perforated valve kas more advantages in each experimental parameters such as in cylinder gas pressure, mass burnt ratio, fuel consumption rate, and pollutant emission characteristics than that of solid one equipped. No matter what the same perforated valve, there are some distinct results in engine performance characteristics according to the perforate ratio.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.8 no.2
• /
• pp.81-91
• /
• 2000

Dynamic models of line regulator valve(LRV) and ratio control valve (RCV) are obtained for an electronic controlled CVT. LRV and RCV are operated by variable force solenoid(VFS). Considering the CVT shift dynamics, oil pump's efficiency and saturation characteristics of VFS, simulations are performed and compared with test results. Simulation results are in good agreement with the experiments, which shows the validity of the dynamic models of LRV and RCV obtained. In addition, the effects of the orifice size in the exhaust port of RCV are investigated. Simulation results show that as the orifice size decreases, the residual pressure in the primary actuator increases which insures the large torque transmission capacity, meanwhile the duration time for the downshift increases.

• Journal of ILASS-Korea
• /
• v.1 no.1
• /
• pp.55-62
• /
• 1996

In a fuel injection engine, atomization of liquid fuel and mixture formation process has influenced(or affected) directly on the engine performance and pollutant emission. In this study, the characteristics of fuel spray and the behaviors of secondary atomization developed at the downstream of the valves were investigated using an image processing method. Solid and perforated valves are chosen in order to evaluate the valve performance in terns of air flow rate, valve opening angle and valve shape. Experimental results clearly indicate that the spray atomization quality can be improved by increasing the perforated rat io and the blockage rat io in the perforated valve, the characteristics of spray atomization is improved by using the perforated valve with high perforated rat io and blockage ratio.

• Journal of Industrial Technology
• /
• v.19
• /
• pp.51-57
• /
• 1999

This research has an object to find out how the position of inlet valve influence swirling and tumbling of turbulence inside the combustion chamber of 4 valve engine. The computational analysis of three dimensional complicated turbulence flow in the cylinder is done by the KIVA-3V program to carry out this object. One use 6 valve positions with the bowl type of piston cavity. The swirl ration and the tumbling ratio of flow filed are evaluated quantitatively to find out how each valve position influence flow phenomena in the combustion chamber during the intake and compression processes.

• Journal of Biomedical Engineering Research
• /
• v.12 no.3
• /
• pp.149-156
• /
• 1991

In this paper, fluttering behavior of mechanical bileaflet heart valve prosthesis was analyzed taking into consideration of the impact between valve plate and stopper Vibration system of the valve was modeled as a rotating system, and equations are induced by moment equilibrium equations. Lift force, drag force, gravity and buoyancy were considered as external forces acting on the valve plate/ The 4th order Runge-Kutta method was used to solve the equations. Valve plate does not come to the static equilibrium position at a stretch, but come to that position after under damping vibration. Damping ratio increases as the cardiac optput increases, and the mean damping ratio is in the range of 0.16~40.25. Fluttering frequency does not have any specific value, but varies as a function of time. It is in the range of 10~40Hz. Valve opening appears to be affected by the orientation of the of the valve relative to gravitational forces.

• Proceedings of the KSME Conference
• /
• 2004.11a
• /
• pp.1698-1703
• /
• 2004

To understand the high expansion effects by adopting intake closing time in the cases of compensating intake air-mass and effective compression ratio simultaneously, fundamental study was carried out by using RICEM realizing Atkinson cycle. Intake air-mass and effective compression ratio were compensated by increasing supercharged pressure and geometric compression ratio. The results showed that the increasing rates of expansion ratio and expansion-compression ratio were increased by compensating both a intake air-mass and effective compression ratio the same tendencies were obtained with the increases of compression ratio and cut off ratio It was also found that LIVC has more advantages in expansion ratio and effective work than those of EIVC under above conditions.