• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.2
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• pp.32-38
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• 2004

This study was performed to investigate the behavior of liquid and vapor phase of fuel mixtures with different piston cavity diameters in a optically accessible engine. The conventional engine was modified as Central Injected DI gasoline engine with swirl motion. Two dimensional spray fluorescence images of liquid and vapor phase were acquired to analyze spray behavior and fuel distribution inside of cylinder using exciplex fluorescence method. Piston cavity geometries were set by Type S, M and L. The results obtained are as follows. In the spray formation after SOI, the cone angle and width of the spray were decreased at late injection timing. With a fuel injection timing of BTDC $180^{\circ}C$, fuel was not greatly affected in a piston cavity but generally distributed as homogeneous mixture in the cylinder. With a fuel injection timings of BTDC $90{\circ}C$ and $60^{\circ}C$, fuel mixture was widely distributed in near the cavity center. As a injection timing was late in the compression stroke, residual width of fuel mixture was narrow in proportion to piston cavity.

• Tribology and Lubricants
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• v.22 no.3
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• pp.155-163
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• 2006

Ring, groove and cylinder bore wear may not be a problem in most current automotive engines. However, a small change in ring face, groove geometry and cylinder bore diameter can significantly affect the lubrication characteristics and ring axial motion. This in turn can cause to change inter-ring pressure, blowby and oil consumption in an engine. Therefore, by predicting the wear of piston ring face, ring groove and cylinder bore altogether, the changed ring end gap and the changed volume of gas reservoir can be calculated. Then the excessive oil consumption can be predicted. Being based on the calculation of gas flow amount by the theory of piston ring dynamics and gas flow, and the calculation of oil film thickness and friction force by the analysis of piston ring lubrication, the calculation theory of oil amount through top ring gap into combustion chamber will be set. This is estimated as engine oil consumption. Furthermore, the wear theories of ring, groove and cylinder bore are included. Then the each amount of wear is to be obtained. The changed oil consumption caused by the new end gap and the new volume of oil reservoir around second land, can be calculated at some engine running interval. Meanwhile, the wear amount and oil consumption occurred during engine durability cycle are compared with the calculated values. Next, the calculated amount of oil consumption and wear are compared with the guideline of each part's wear and oil consumption. So, the timing of part repair and engine life cycle can be predicted in advance without performing engine durability test. The wear data of rings, grooves and cylinder bore are obtained from three engines before and after engine durability test. The calculated wear data of each part are turn out to be around the band of averaged test values or a little below.

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.1
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• pp.31-38
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• 2006

Cylinder liner rotation is a new concept for reducing piston assembly friction in the internal combustion engine. The purpose of cylinder liner rotation is to reduce the occurrence of boundary and mixed lubrication friction in the piston assembly. This paper reports the results of experiments to quantify the potential of the rotating liner engine. A GM Quad-4 SI engine was converted to single cylinder operation and modified for cylinder liner rotation. The hot motoring method was used to compare the friction loss between the baseline engine and the rotating liner engine. Additionally, tear-down tests were used to measure the contribution of each engine component to the total friction torque. The cycle-averaged motoring torque of the RLE represents a $23\~31\%$ friction reduction compared to the baseline engine for hot motoring tests. Through tear down tests, it was found that the piston assembly friction of the baseline engine is reduced from $90\%$ at 1200 rpm to $71\%$ at 2000 rpm through liner rotation.

• Transactions of the Korean hydrogen and new energy society
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• v.17 no.2
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• pp.227-233
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• 2006

A free-piston hydrogen fueled engine is considered as one of the next power systems which is able to obtain high efficiency and low emission, simultaneously. In this study, in order to ensure the possibility as the next generation power system, the combustion characteristics and the performance of the free-piston hydrogen fueled engine are analyzed by using the linear RICEM for the change of injection pressure and equivalence ratio. As the results, in-cylinder maximum pressure is shown at injection pressure $P_{inj}$=6bar. Backfire phenomenon is not observed under experimental condition and knock occurs over ${\Phi}=0.8$. The thermal efficiency is the highest at injection pressure, $P_{inj}$=6bar and equivalence ratio, ${\Phi}=0.7$, respectively.

• Journal of Energy Engineering
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• v.23 no.3
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• pp.221-230
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• 2014

Simplified finite element model of spark ignition (SI) engine to analyse combustion heat transfer is presented. The model was discredited with 3D thermal elements of global length 5 mm. The fuel type is petrol. Internal nodal temperature of cylinder body is defined as 21000C to represent occurrence of gasoline combustion. Material information and isotropic material properties are taken from published report. The heat transfer analysis is done for the instant of combustion. The model is validated by comparing the computed maximum temperature at the piston surface with the published result. The computed temperature gradient at the crucial parts are plotted and discussed. It has been found that the critical top surface suffered from thermal and the materials used to construct the engine parts strongly influenced the temperature distribution in the engine. The model is capable to analyze heat transfer in the engine reasonably and efficiently.

• Journal of Power System Engineering
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• v.2 no.2
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• pp.27-34
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• 1998

The purpose of this study is to investigate the performance of swirl combustion chamber diesel engine by changing the jet passage area and its angle, the depth and shape of the piston top cavity(main chamber). The performance of diesel engine with newly changed swirl combustion chamber was tested through the experimental conditions as engine speed, load and injection timing etc. The test results were compared and analyzed. The rate of fuel consumption was affected significantly by the jet passage area at the high speed and load, by the depth of the piston top cavity at the low speed and load. The exhaust smoke density and exhaust gas temperature depended sensitively on variation of the injection timing rather than the shape of the combustion chamber within the experimental conditions.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.11a
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• pp.207-207
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• 2000

Fuel consumption of a modern combustion engine is significantly influenced by the mechanical friction losses. The reduction of the engine friction losses offers a remarkable potential in emission and fuel consumption reduction. The analysis of the engine friction distribution of modern engines shows that the piston and the cylinder have a high share at total engine friction. The present study uses PISDYN(by Ricardo) software to analyze the friction losses. The design parameters such as skirt profile, center of mass of the piston are shown to have key influences on the friction losses.

• KSTLE International Journal
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• v.1 no.2
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• pp.101-106
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• 2000

Variable displacement axial piston pumps are widely used for raising the energy level of the fluid in hydraulic systems. And the regulator is the device which regulates the discharge flow of the piston pump by controlling the swivel angle. The regulator receives the hydraulic pilot pressure and controls the pump output flow depending on the machine load and engine speed. This work deals with constant power control (horsepower control) in the design of a regulator by using a bent-axis type piston pump. In order to effectively use engine power, we must keep the horsepower from the engine to the pump constant. Therefore the regulator operates the constant power control. As a result, optimum power usage is obtained by accurately following the power hyperbola. This study focused on developing a simulation model of a regulator. First, the governing equations of the regulator are derived, and analysis is performed by computer simulation, which can identify significant parameters of regulator. As a result, the variation of the swivel angle, flow rate, hyperbolic curve, inner leakage and responsibility are simulated, and significant parameters of a regulator are identified.

• Transactions of the Korean hydrogen and new energy society
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• v.26 no.3
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• pp.294-299
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• 2015

Free piston linear engine (FPLE) is a promising concept being explored in the mid-20th century. On the other hand, Arficial neural networks (ANNs) are non-linear computer algorithms and can model the behavior of complicated non-linear processes. Some researchers already studied this method to predict internal combustion engine characteristics. However, no investigation to predict the performance of a FPLE using ANN approach appears to have been published in the literature to date. In this study, the ability of an artificial neural network model, using a back propagation learning algorithm has been used to predict the in-cylinder pressure, frequency, maximum stroke length of a free piston linear engine. It is advised that, well-trained neural network models can provide fast and consistent results, making it an easy-to-use tool in preliminary studies for such thermal engineering problems.

• Journal of the Korean Society for Heat Treatment
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• v.20 no.2
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• pp.72-77
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• 2007

Abrasive wear between piston ring face and cylinder liner is an extremely unpredictable and hard-to-reproduce phenomenon that significantly decreases engine performance. Wear by abrasion are forms of wear caused by contact between a particle and solid material. Abrasive wear is the loss of material by the passage of hard particles over a surface. From the pin-on-disk test, particle dent test and scuffing test, abrasive wear characteristics of diesel engine cylinder liner-piston ring have been investigated. Pin-on-disk test results indicate that abrasive wear resistance is not simply related to the hardness of materials, but is influenced also by the microstructure, temperature, lubricity and micro- fracture properties. In particle dent test, dent resistance stress decreases with increasing temperature. From the scuffing test by using pin-on-disk tester, scuffing mechanisms for the soft coating and hard coating were proposed and experimentally confirmed.