• 유체기계공업학회:학술대회논문집
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• 1998.02a
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• pp.3-10
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• 1998

The situation frequently occurs in which the input torque capacity of the converter should be changed. It is known that the modification of the ou angles of the torque converter elements is suitable for such situation with diameter of flow path of the converter maintained. But so far it has been, predict correctly the converter characteristics as well as the effects of oulet torque capacity in the past numerical methods. In the present numeric introducing the interrow mixing planes, the torque capacity was satifactorily and it was shown that the torque capacity could be effectively changed by the oulet blade angles of pump and stator.

• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.6
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• pp.174-184
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• 1998

The situation frequently occurs in which the input torque capacity of the torque converter should be changed. It is known that the modification of the outlet blade angles of the torque converter elements is suitable for such situation with the outer diameter of flow path of the converter maintained. But so far it has been difficult to predict correctly the converter characteristics as well as the effect of outlet angles on torque capacity in the past numerical methods. In the present numerical method introducing the interrow mixing planes, the torque capacity was satisfactorily estimated and it was shown that the torque capacity could be effectively changed by modifying the outlet blade angles of pump and stator.

• The KSFM Journal of Fluid Machinery
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• v.1 no.1 s.1
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• pp.90-104
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• 1998

The automotive torque converter is a complex turbomachine used to transfer power smoothly from an engine to a transmission. Its hydrodynamic design technology has been advanced very much during the past few years. A review of technologies for developing the torque converter was presented. In this paper, the technologies in the torque converter were divided into four parts: one-dimensional analysis, experimental study, numerical study, and new design method of the torque converter. In order to provide useful guidances to the torque converter designer, numerous papers published previously were incited and summarized briefly in this paper.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.1
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• pp.244-254
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• 2002

To enhance the acceleration performance and fuel consumption rate of a vehicle, the torque converter is modified or newly-developed with reliable analysis model. Up to recently, the one dimensional performance model has been used for the analysis and design of torque converter. The model is described with constant parameters based on the concept of mean flow path. When it is used in practice, some experiential correction factors are needed to minimize tole estimated error. These factors have poor physical meaning and cannot be applied confidently to the other specification of torque converter. In this study, the detail dynamic model of torque converter is presented to establish the physical meaning of correction factors. To verify the validity of model, performance test was carried out with various input speed and oil temperature. The effect of oil temperature on the performance is analysed, and it is applied to the dynamic model. And, to obtain the internal flow pattern of torque converter, CFD(Computational Fluid Dyanmics) analysis is carried out on three-dimensional turbulent flow. Correction factors are determined from the internal flow pattern, and their variation is presented with the speed ratio of torque converter. Finally, the sensitivity of correction factors to the speed ratio is studied for the case of changing capacity factor with maintaining torque ratio.

• 유체기계공업학회:학술대회논문집
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• 2004.12a
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• pp.705-710
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• 2004

In the present study, a transient incompressible viscous turbulent flow is simulated for the automotive torque converter with moving mesh technique. For the analysis, entire torque converter flow passages are modeled. Computed torque ratio, capacity factor and efficiency show a good agreement with the experiment data. The flow instabilities characterized by back-flow and wake etc. appeared in some cascade passages are shown to be Propagating along tangential direction. These flow patterns are mainly influenced by the pump and turbine blade passing and can't be predicted through conventional steady simulation with a mixing plane approach. The understanding of the unsteady flow characteristics in a torque converter achieved in the present study may lead to the optimal design of a torque converter.

• The KSFM Journal of Fluid Machinery
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• v.9 no.5 s.38
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• pp.36-41
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• 2006

In the present study, a transient incompressible viscous turbulent flow is simulated for the automotive torque converter with moving mesh technique. For the analysis, entire torque converter flow passages are modeled. Computed torque ratio, capacity factor and efficiency show a good agreement with the experiment data. The flow instabilities characterized by back-flow and wake etc. appeared in some cascade passages are shown to be propagating along tangential direction. These flow patterns are mainly influenced by the pump and turbine blade passing and can't be predicted through conventional steady simulation with a mixing plane approach. The understanding of the unsteady flow characteristics in a torque converter achieved in the present study may lead to the optimal design of a torque converter.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.3 s.174
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• pp.718-727
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• 2000

Nowadays, most passenger cars equipped with automatic transmissions use torque converter clutches to reduce fuel consumption, and recently the slip control scheme of torque converter clutches is widely studied for the expansion of the operating region of torque converter clutches and thus for the further improvement of the fuel economy of vehicles. In this study, the analysis of the torque converter clutch system including the line pressure control unit of the automatic transmission and the actuating hydraulic control unit of the torque converter clutch is performed, and a feedforward controller and a fuzzy logic controller for its slip control are proposed. Also, for the slip controller to use the grade resistance information during control, an observer-based grade resistance estimator is designed. The performance of the designed grade resistance estimator and the slip controller is verified by dynamic simulations, and the effect of the torque converter clutch slip control on the fuel economy is examined using a driving cycle simulation.

• Proceedings of the KSME Conference
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• 2000.04a
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• pp.678-683
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• 2000

The one-dimensional performance model of a torque converter has been widely used to analyze and predict the performance and dynamic behavior of a torque converter. But this model doesn't include the information of the operating fluid properties. Therefore, to precisely predict dynamic performance of a torque converter, the effect of operating conditions must be considered through experimental coefficients such as friction loss coefficient and shock loss coefficient. And these coefficients cannot be achieved without experiments or internal flow analysis. In this study, the effects of varying material properties of operating fluid according to various operating temperatures are clarified with flow analysis of a torque converter. And these results are verified by comparing with those of performance experiment.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.22 no.3
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• pp.326-335
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• 1998

In this study, a steady three-dimensional incompressible turbulent flow within a torque converter was numerically analyzed with the introduction of interrow mixing model. Mixing planes were introduced to exchange the flow informations between two adjacent elements of the torque converter. The mixing planes were installed among three elements of the torque converter. Therefore, in the present method, it could be possible to calculate the flow-filed within the torque converter without any assumption of circulating flow rates or any extension of boundaries toward the upstream and the downstream for each element. The numerically calculated performances of the torque converter were in good agreement with experimental results, and the complex flow patterns were be observed according to design and off-design condition. As a conclusion, it was found that the present numerical method was very effective in the steady flow analysis of torque converters.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.690-695
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• 2004

The present study is an investigation on the characteristics of heavy load toque converter by experimental process. To get the dynamic performance, the dynamometer was used with a parameters of speed, torque, oil pressure and oil flux, etc. The torque converter was tested for various input speed, output oil pressure and input oil flow rate. All experiments were investigated in case that the speed ratio is increased. The torque ratio and capacity factor was in inverse proportion to speed. Engine revolution had a more effects at region of low speed ratio. But, the opposite phenomena were represented increase of efficiency. In result of this experiments, the characteristics of torque converter were not influenced by oil pressure and oil flux.