• Transactions of the Korean Society of Automotive Engineers
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• v.17 no.4
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• pp.63-71
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• 2009

The elastic effects of the valve train components are analyzed by using the finite element models of the rocker arm and valve. The whole equations of motion of the valvetrain of an internal combustion engine formulated by finite element techniques are solved by imposing the contact conditions with the augmented Lagrange multiplier method. The velocity and acceleration constraints as well as the displacement constraints are imposed on the contact points. The numerical simulations show that, even if the magnitude of the elastic deformation of the components is very small, it may have large effects on the valvetrain dynamics of a high-speed engine.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.31 no.3 s.258
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• pp.242-247
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• 2007

Energy savings and environmental protection policies have been the general trend in the engine design. The friction power loss associated with the cam mechanism has become important. But it is difficult to measure the torque of rotating valvetrain in real engine environment because most of conventional torque meters are axial type. The objective of this paper is to develop new equipment which can be installed in a rotating camshaft. It uses strain gages to measure the elastic deformation of torque sensor which replaces the cam sprocket. It includes telemetry to transmit torque data via Bluetooth and induction power system to provide adequate power to rotating torque meter. The developed torque meter has good linearity and thermostability. It was installed in a real engine, and successfully measured the valvetrain torque.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.11
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• pp.223-229
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• 2016

In this study, a cold forging process was developed for the roller tappet housing of an engine valvetrain system. A tappet sample was manufactured and subjected to an endurance test. The material properties were obtained from a compression test, and forging analysis was carried out to design a forging process using a commercial program, Deform-3D. The forging process was set up based on the analysis results, and a die set and sample tappet housing were manufactured. To evaluate the sample, the dimensional accuracy, surface roughness, parallelism, and concentricity were measured and confirmed. To evaluate the actuation and durability, a special test rig was developed to simulate the valvetrain system of the engine. An actuation test was performed based on the idle speed of a general diesel engine, and an endurance test was done based on the maximum speed. The results show minor wear of 0.002 mm. The developed test rig will be used to evaluate the actuation and durability of other valvetrain parts.

• Journal of the korean Society of Automotive Engineers
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• v.24 no.4
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• pp.42-43
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• 2002

• Journal of Mechanical Science and Technology
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• v.15 no.6
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• pp.685-692
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• 2001

This paper reports on the mixed lubrication characteristics between the cam and the tappet contact surface of direct acting type valve train systems. First, the dynamic characteristics are solved by using the lumped mass method to determine the load conditions at the contact point. Then, the minimum oil film thickness is calculated with consideration of elastohydrodynamic line contact theory and the friction force is obtained by using the mixed lubrication model which separates the hydrodynamic and the boundary friction. Finally, the average surface temperatures are calculated by using the flash temperature theory. The results show that, there are some peaks in the friction force due to the asperity contact friction, and flash temperature at the position of minimum oil film thickness. It is thought that there is a relationship between the surface temperature and cam surface wear, and therefore, the analysis on the worn cam profile has been performed.

• Journal of ILASS-Korea
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• v.22 no.1
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• pp.22-28
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• 2017

In this study, the effects of intake valve closing timing by using Cam-in-Cam system on combustion and emission characteristics for diesel engine were investigated under GT-POWER simulation environment. As a result, it was found that volumetric efficiency and effective compression ratio were decreased as the intake valve closing(IVC) timing is retarded due to its backflow effect. Also, we found that in-cylinder pressure, heat release rate and NOx emission were decreased as IVC timing was retarded. These show that the LIVC(late intake valve closing) can be effective to control AFR and mixing rate in diffusion combustion of diesel engine.

• Journal of ILASS-Korea
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• v.20 no.3
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• pp.141-148
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• 2015

In order to research engine characteristics of spark-ignited engine with intake valve closing timing change for Miller cycle, two cam for LIVC(Late Intake Valve Closing) were designed and fabricated an prototype valvetrain. And intake valve closing timing were adjusted to build low compressing and high expansion cycle for HEV. In experimental study, it were investigated with different engine speed, spark timing and air-fuel ratio to compare base cam and LIVC cam type. It was found that the volumetry efficiency and effective work of compression process were decreased in case of LIVC cam. When compared with the existing results, the maximum pressure in the cylinder was reduced about 12~13 bar and the volumetric efficiency was reduced about 16%.

• Journal of ILASS-Korea
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• v.23 no.2
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• pp.58-65
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• 2018

An analytic strategy to control the variable valve actuation applied to two intake valves (flow port intake valve and swirl port intake valve) was performed in this study. we considered the variation in phasing of intake valve profiles by using the Cam-in-Cam technology. The analytic model was implemented in the GT-Power simulation program and analyzed the result of regulated emissions such as, NOx and Soot, especially with IMEP characteristics. Namely, we meticulously investigated the sources of having effect on the amount of NOx and soot formation under the test conditions with retard timing of both flow port and swirl port intake valves for decreasing the opening duration by 35CAD. Also, we analyzed the effect of incylinder pressure and temperature with NOx variations and in-cylinder pressure and temperature on NOx variations and normalized turbulent intensity. Through this analysis, some useful results on the combustion and flow characteristics of the swirl port and flow port control of the intake valve were obtained by this study.