Thermal external cracks can be initiated at the parting line, which is the dividing line that splits the core and cavity halves of a molded exhaust manifold-turbine housing. The fatigue cracks are often resulted from hot-cold cycle loads called by thermal shock cycles, and are accompanied by large plastic strains. This paper investigated the effects of parting lines of the integrated exhaust manifold-turbine housing and compared the magnitude of plastic strains directly correlated to low cycle fatigue damages or cracks. The finite element results showed that the plastic strains at runner junctions including parting line was calculated by 0.68%, which is approximately 60% higher than that of the turbine housing considering no parting line. So, if the analysis target is less than 0.50 % of plastic strain amplitude, the fatigue damages or cracks could be expected by considering the parting lines in integrated exhaust manifold-turbocharger.

V-type coupling, which is often applied to turbochargers, is a mechanical fastener where radial forces close turbine housing and bearing housing together. It prevents leakage of exhaust gases by contact pressure of the backplate caused by the load transmitted from the bolt-tightening torque. Therefore, it is important to study the mechanical behaviors of the coupling system in order to establish more accurate sealing assessment technologies. In this study, an experiment was first conducted to obtain the relationship between torque and its resulting axial force in a specially designed gage bolt. Strains were then measured when the torque was applied using the gauge bolts on the turbocharger. Thus, the magnitude of the axial force due to the bolt torque can be obtained inversely. In addition, the circumference and width strains of the turbocharger coupling were measured under the assembly load, and theses results were compared with the finite element results. As a result, they tend to be very similar, but in the ring area, analysis results show a relatively small value, and near the bolt, the analysis results are larger than the experimental strains. This is thought to be due to the reduced strains around the bolt by the hammering process.

The wastegate valve regulates the maximum boost pressure inside the turbocharger to prevent damage to the engine and turbocharger which can occur from overload. However, even though the opening and closing behaviors of the valve should be controlled accurately, thermal deformations of the turbocharger system can lead to excessive distortion of the actuator rod, which can have a significant effect on the turbocharger performance. In this study, thermal deformation analysis of the turbocharger assembly has been analyzed through finite element analysis under operation condition. The result shows that the deformation in the turbine housing is relatively large and actuator rod is bent by thermal load. It causes rotational deformation at the wastegate valve face connected to the rod. And it is efficient to increase the stiffness of the EWGA rod to minimize the rotational deformation of the valve face. It means that the actuator rod should be placed in a position close to the center of the turbocharger to minimize the length of the rod that has the greatest effect on stiffness enhancement.

Coupling is commonly used as a mechanical fastener to connect the turbine housing and the bearing housing in a turbocharger assembly. The finite element analysis was used to predict the structural behaviors of the coupling system, which could be caused by the bolt clamping force in the assembly process and the thermal deformation during turbocharger operation. The back plate is used to prevent gas leakage from the turbine housing to the bearing housing while the fixed pin is inserted to set the reference position between the two parts. Thus, in order to predict the mechanical behaviors of the coupling system numerically, the temperature distributions were calculated by heat transfer analysis based on the rated speed of the diesel engine. As a result of analyzing the structural characteristics of the turbocharger, the contact pressure of the back plate was influenced by thermal deformations whereas the bending deformation of the fixed pin was affected by the thermal deformation and the pin position.

V-Coupling is used as a mechanical fastener to connect the turbine housing and the bearing housing in a turbocharger. The back plate is located between the turbine housing and the bearing housing, which is compressed by the bolt clamping force of coupling to prevent gas leakage under turbocharger operation. This paper presents the theoretical and analytical methods to predict the sealing performance by calculating the contact pressures on the back plate. The mathematical model was constructed to derive the contact force on the back plate by considering the force transfer mechanism. And, finite element analysis was carried out to predict the contact pressures by applying the bolt load in the coupling system. As a result, the analysis results of the mathematical model are well consistent with the results of the finite element analysis. Therefore, in the early design stage of turbocharger coupling, mathematical model would be helpful to determine the design parameters.

V-Coupling is commonly used as a mechanical fastener to connect the turbine housing and the bearing housing in a turbocharger assembly. The back plate between the turbine housing and bearing housing would be compressed by tightening torque of the coupling bolt in order to protect the gas leakage at a turbocharger’s operation. This paper presents the numerical and experimental method for the prediction of the mechanical behavior and sealing performance of the coupling system. The test was conducted to verify the finite element model by measuring the circumferential and axial direction strains of V-coupling under turbocharger’s assembly load. Finite element analysis was carried out to obtain the mechanical strains and contact pressures of the coupling. It can be seen that the analysis results are in good agreement with the measured strains from the coupling’s assembly load. And, the pressure distribution of the back plate also presented to identify the sealing performance of the turbocharger’s coupling system.

Recently, car industry trend is downsizing, a lean-burn engine, green car and cost cutting. A turbocharger is the key components to improve fuel efficiency and power. This research is to study on the flow analysis in the performance analysis for change rotating speed of turbocharger turbine with three different rotating speed in the turbine. After measuring real design features, modeling, velocity distribution, pressure distribution and temperature distribution are conducted numerically. Torque and power are compared with three different cases in order to analyze the performance for turbine. Finally, optimum power is determined with the sequence of case 1, case 2, and case 3.

The axial thrust acting on the turbocharger rotor is basically generated by the unbalance between turbine wheel gas forces and compressor wheel air forces. It has a significant influence on the friction losses, which reduces the overall efficiency and performance of high-speed turbocharger. Therefore, it’s important to calculate the thrust forces under operating conditions (surge, choke and etc.) in a turbocharger. The purpose of this paper is the development of numerical simulation methods which were verified by experimental results of axial thrust and thermally induced constraint tests of the turbocharger. The first FE model showed the relationship between thrust forces and strains by calculating the strains on specially designed thrust bearing and were compared with test results. And the second one is to identify the thermally induced strains in order to remove the thermal effects from measured strains. With these models, it’s possible to inversely predict the magnitudes of the axial thrust by directly measured strains and temperatures under operating turbocharger.

In this paper, the main objective is to determine the mechanical responses due to the axial forces on thrust bearing for an automotive turbocharger. The rotating shaft in a turbocharger is supported by the bearings, usually oil-lubricated radial journal bearings and a thrust bearing. The axial forces acting on the thrust bearing have significant influences on the mechanical friction losses, which reduces the efficiency and performance of high-speed turbocharger. There are simple well-known formulas such as Petroff’s equation for calculating the mechanical frictional losses in these types of bearings. However, it's difficult to estimate the accurate axial forces from this formula. Thus, this work determined the relationship between thrust forces and strains by measuring and calculating the strains on thrust bearing and compared both results. The result shown that behaviors of axial strain are changed linear and non-linear depend on the boundary condition. Therefore, it’s possible to predict the magnitudes of the axial forces by measuring the strains under operating turbocharger.

터보 노즐에 유동하는 가스 에너지의 변화와 그위상의 조정에 의하여 디젤엔진의 성능 개선 가능성을 검토 하였다. 그리고 디젤기관의 각실린더와 터빈 노즐 면적과 가스의 유동에 대한 동기화를 실시함으로써 엔진 성능 또한 개선할 수 있었다.