• Transactions of Materials Processing
• /
• v.18 no.6
• /
• pp.465-470
• /
• 2009

The frictional behaviors of Cermets/Cr-Ceramics and Cu-Al coatings of piston ring were investigated. Friction tests were carried out by pin-on-disk test and materials properties of coating layer were analyzed by nano indentation tester. The effect of surface roughness of cylinder liner on the friction coefficient was analyzed. This study provided tribological data of hard and soft piston ring coatings against cylinder liner. The surface roughness does exert an influence on the average friction coefficient, with smoother surfaces generally yielding lower friction coefficients. In case of hard-coating, the scratch depth, width and pile-up height had close relationship with hardness. So the scratch width, depth and pile-up height increases with decreasing friction coefficient. But in case of soft-coating, the friction coefficients are strongly dependent on the morphological characteristics such as, scratch depth, width, pile-up height and elastic modulus.

• Journal of ILASS-Korea
• /
• v.26 no.2
• /
• pp.57-66
• /
• 2021

The reactivity controlled compression ignition (RCCI) is the technology that provides two different types of fuel to the combustion chamber with the advantage of significantly reducing particulate matter and nitrogen oxides emissions. However, due to the characteristics of lean combustion, combustion efficiency is worsened. The conventional type of pistons for conventional diesel combustion (CDC) has mostly been used in the researches on RCCI. Because the pistons for CDC are optimized to enhance flow and target spray, the pistons are unsuitable for RCCI. In this study, a piston that is suitable for RCCI is designed to improve combustion efficiency. The new piston was designed by considering the factors such as squish geometry, bowl depth, and surface area. The experiment was carried out by fixing the energy supply to 0.9kJ/cycle and 1.5kJ/cycle respectively. The two pistons were quantitatively compared in terms of thermal efficiency and combustion efficiency.

• Tribology and Lubricants
• /
• v.2 no.1
• /
• pp.18-29
• /
• 1986

한국철도에서는 현재 약 450냥에 가까운 Diesel 기관차를 보유하고 있으며 기관의 정밀검사를 위한 Enginer의 Overhaul은 2Y검사로 2년마다 실시하고 있다. 원래 Engine의 Overhaul 주기간격은 Liner Bore와 Piston Ring 등 동력장치 조립체의 구성부품의 체험적인 마모율을 감안하여 결정되며 가장 경제적이면서도 무장애운행을 가능케 하는 것은 마모율이 최저로 유지되고 있을 때이다. 따라서 기관의 마모를 최대로 억제하는 것이 바람직하다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2013.10a
• /
• pp.479-480
• /
• 2013

• Journal of Advanced Marine Engineering and Technology
• /
• v.32 no.3
• /
• pp.430-436
• /
• 2008

Recently, there are many cases to use a ship's engine performance analyzer(SEPA) to measure pressure in cylinder and top dead center(TDC) of piston of engine, and analyze its performance such as fuel injection time and horsepower as well as wear of piston ring. But, SEPA needs TDC pulses($T(1){\sim}T(n)$) generated when pistons of engine are located to the TDC position ($TDC(1){\sim}TDC(n)$), these pulses are gathered from sensors connected to gear wheel of the propeller shaft in the remote distance from the measurement point. Therefore, operators need a long wire cable(WRC) to TDC detecting sensor to get these pulses, but this method is a very uncomfortable and expensive in case of installation, and it might decrease user's purchase desire. In this paper, we design and fabricate a small and inexpensive MODEM cable(M0C) so that it may be available to transmit TDC pulse generated from sensor in propeller shaft through existing power line. We also verify the facts that this MOC can be applied to SEPA and the effectiveness of the system through the experiments.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.6 no.5
• /
• pp.211-221
• /
• 1998

Thermal behavior on the cylinder block of a 4-cylinder, 4-stroke 2.0L SOHC gasoline engine was numerically and experimentally analyzed. The numerical calculation was performed using the finite element method. The cylinder block was modelled as a three dimensional finite element by considering its geometry. The physical domain was devided into hexahedron elements. 16 thermocouples were installed at points of 2mm inside from cylinder wall near top ring of piston in cylinder block, which points have suffered major thermal loads and suggested as proper measurement points for engine design by industrial engineers. Under full load and 9$0^{\circ}C$ coolant temperature condition, temperature behavior of cylinder block according to engine speed were analyzed. The results showed that temperature rose gradually to conform to a function of 2nd~4th order of engine speed at intake side, exhaust and siamese side, respectively. As engine load was changed from 100 to 50% by 25% step, temperature curve also conformed to 2nd~7th order function of engine speed. Temperature differences by load condition were similar among 100, 75% and 50%. Under full load and coolant temperature of 11$0^{\circ}C$, temperature behavior were also analyzed and the result also showed conformance to 2n d~7th order function of engine speed. Temperature curve was transferred in parallel upwards corresponding coolant temperature rise.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.28 no.9
• /
• pp.1075-1080
• /
• 2004

In this study, performance and emissions characteristics of an liquefied petroleum gas (LPG) engine converted from a diesel engine were examined by using mixer system and liquid propane injection (LPi) system fuel supply methods. A compression ratio for the base diesel engine, 21, was modified into 8, 8.5, 9 and 9.5. The cylinder head and the piston crown were modified to roe the LPG in the engine. Ignition timing was controlled to be at minimum spark advance for best torque (MBT) each case. Engine performance and emissions characteristics are analyzed by investigating engine power, brake mean effective pressure (BMEP), brake specific fuel consumption (BSFC), volumetric efficiency, CO, THC and NOx. Experimental results showed that the LPi system generates higher power and lower emissions than the conventional mixer fuel supply method.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.11 no.6
• /
• pp.7-13
• /
• 2003

The purpose of this study is to investigate the effect of the in-cylinder flows and different injection timings on fuel behavior in the cylinder of a GDI engine. Three different flows types induced by using masked port, unmasked port, and port deactivation were tumble, swirl&tumble, and high swirl respectively. LIEF technique was applied to investigate the mixture formation and fuel distribution at ignition time in the transparent engine with optical access through the piston top and upper part of cylinder liner. Injection timings of 180,90, and 60 degrees before TDC were examined. It was found that tumble flow was more effective on the homogeneous mixture formation than other flow and swirl flow transported more fuel vapor to the exhaust side at early injection mode, and swirl and swirl & tumble flow made fuel vapor concentrate around the cylinder center at late injection mode.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.7 no.6
• /
• pp.57-64
• /
• 1999

Initial flame development and propagation were visualized under the new ignition system developed to estimate the effects of ignition characteristics on the engine performance in a port injection SI engine. Effects of intake air flow characteristics were also investigated by three different kinds of the swirl control valve. Experiments were performed in an optical single cylinder engine modified form a commercial engine. Flame images were captured through the quartz window mounted in the piston by the high speed video camera and analyzed to compare initial flame development. Results show that IMEP tends to rise slightly as the ignition duration gets longer. The direction of flame propagation is decisively governed by the in-cylinder flow motion. Every flame grows toward the exhaust valve forming a kind of turbulent flame. Initial flame propaagation characteristics are very similar to ones analyzed form pressure data.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.15 no.5
• /
• pp.153-159
• /
• 2007

The performance of a direct-injection type diesel engine often depends on the strength of air flow in the cylinder, shape of combustion chamber, the number of nozzle holes, etc. This is of course because the process of combustion in the cylinder was affected by the mixture formation process. In the present paper, high speed photography was employed to investigate the effectiveness of holes penetrated from the bottom of cavity wall to piston crown for some more useful utilization of air. The holes would function to improve mixing of fuel and air by the increase of air flow in the cylinder. The results obtained are summarized as follows, (1) Activated first of the combustion by shorten of ignition timing and rapid flame propagation (2) Raised the combustion peak pressure, more close to TDC the formation timing of peak pressure.