• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.602-603
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• 2014

A gearbox can be regarded as a self-exciting dynamic system, which has a vibration source. Transmission error (TE) is considered to be an main excitation source for gear noise and vibration. The TE excitation is transmitted through the gears, shafts, bearings, and housings. Thus, an experimental approach to each mechanical parts is useful in order to understand and evaluate the dynamic behaviour of a gearbox. This study is focused on the transmission and vibration characteristics of a helical gear system in development stage. In addition, by considering the tolerance factors and resonance characteristics, the vibration response of actual dynamic system is analysed.

• Structural Engineering and Mechanics
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• v.55 no.4
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• pp.839-856
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• 2015

A multi-contact tooth meshing model for helical gear pairs considering bearing and shaft deformations is proposed. First, to easily incorporate into the system model, the complicated Harris' bearing force-displacement relationship is simplified applying a linear least square curve fit. Then, effects of shaft and bearing flexibilities on the helical gear meshing behavior are implemented through transformation matrices which contain the helical gear orientation and spatial displacement under loads. Finally, true contact lines between conjugated teeth are approximated applying a modified meshing equation that includes the influence of tooth flank displacement on the tooth contact induced by shaft and bearing displacements. Based on the model, the bearing's force-displacement relation is examined, and the effects of shaft deformation and external load on the multi-contact tooth mesh load distribution are also analyzed. The advantage of this work is, unlike previous works to search true contact lines through time-consuming iterative strategy, to determine true contact lines between conjugated teeth directly with presentation of deformations of bearings and shafts.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.14 no.2
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• pp.1-6
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• 2015

Transmission of a tracked vehicle designed for multiple functions such as steering, gear-shifting, and braking is a core component of heavy vehicle to which the power is transferred based on combined technology of various gears, bearing, and fluid machineries. Robustness and durability of transmission, however, have been issued due to a large number of driving units and sub-components inside its body. The bevel gears are major components for the transmission of power in a transmission. Increasing the tooth surface roughness and chamfering of the bevel gears, especially, we aim to improve the quality of transmission. In this study, design structural evaluation is conducted on bevel gears of transmission for tracked vehicle using the ROMAX-DESIGNER program. By doing so, design safety of the bevel gears has been evaluated based on the gear strength theory of ANSI/AGMA 2003 B97 standard.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.23 no.7 s.166
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• pp.1238-1244
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• 1999

Using a cylindrical worm gear under the actual condition of static loading, tooth fillet strains and transmission errors have been measured. The maximum strain occurs on the filet region of the center of the 1st mating tooth. Tooth fillet strain changes most sensitively according to the variations of the center distance and recess side eccentricity than the access side eccentricity. Even the no-backlash worm gear shows the transmission errors.

• Transactions of the Korean Society of Automotive Engineers
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• v.3 no.6
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• pp.212-223
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• 1995

To improve the efficiency of a power transmission system with slip elements, power split/circulation system is applied. The performance of a power split/circulation system varies widely by the change of the followings; the layout of system, the type and gear ratio of planetary gear, the performance of slip element, etc. Therefore, when one designs such a power transmission system or when one determines the economic/power mode of system, a certain performance prediction method is needed. In this study, the internal power flow pattern of a power split/circulation system is theoretically analyzed on several transmission systems. And an effective performance prediction method(so called performance locus diagram) is presented. By this method, the effects of design factors can be easily understood and the qualitative performances of system can be clearly evaluated.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.5 s.182
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• pp.37-43
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• 2006

Fitting process carried out in automobile transmission assembly line is classified into three classes; heat fitting, press fitting, and their combined fitting. Heat fitting is a method that heats gear to a suitable range under the tempering temperature and squeezes it toward the outer diameter of shaft. Its stress depends on the yield strength of gear. Press fitting is a method that generally squeezes gear toward that of shaft at room temperature by press. Another method heats warmly gear and safely squeezes it toward that of shaft. Warm shrink fitting process for automobile transmission part is now gradually increased, but the parts (shaft/gear) assembled by this process produced dimensional change in both outer diameter and profile of the gear. So that it may cause noise and vibration between gears. In order to solve these problems, we need an analysis of warm shrink fitting process, in which design parameters are involved; contact pressure according to fitting interference between outer diameter of shaft and inner diameter of gear, fitting temperature, and profile tolerance of gear. In this study, an closed form equation to predict contact pressure and fitting load was proposed in order to develop optimization technique of warm shrink fitting process and verified its reliability through the experimental results measured in the field and FEM, that is, thermal-structural coupled field analysis. Actual loads measured in the field have a good agreement with the results obtained by theoretical and finite element analysis and also the expanded amounts of the outer diameters of the gears have a good agreement with results.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.2
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• pp.105-113
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• 2000

For exact spherical involute bevel gear, serveral researchers had developed the mathematical models. The solid models of straight bevel gears are obtained and inspected to avoid interference by computer graphics. Furthermore, A gearbox is assembled by spherical involute bevel gears, which are manufactured by CNC machine. The transmission errors in the tooth mesh are measured by Laser sensor, are compared with the AGMA standard. This gearbox is found to be ranked AGMA Q10(JIS 3)

• Journal of Mechanical Science and Technology
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• v.14 no.5
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• pp.490-498
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• 2000

The authors have proposed methods (lead crowning and profile modification) for modifying the geometry of spur gears and investigated the contact pattern as well as the transmission errors to recommend the appropriate amount of modification. Based on the investigation, dynamic load of the modified spur gear drive has been calculated, which is helpful to predict the life of the designed gear drive. Computer programs for simulation of meshing, contact and dynamics of the modified spur gears have been developed. The developed theory is illustrated with numerical examples.

• Journal of KSNVE
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• v.10 no.1
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• pp.74-81
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• 2000

The vibrational model of a helical gear pair is developed with considering the elastic deformation of the active teeth and the body to be a rigid. The main source of vibration in geared system which has been known to be the gear transmission error is mathematically formulated and used for the analysis of vibrational characteristics of geared system. As an example, a simple geared system containing a helical gearing is considered. The critical speeds are found by the campbell diagram and compared with the experimental results.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.26 no.5
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• pp.559-566
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• 2016

This study shows a development procedure and results of noise reduction for a new developed FF 8th speed automatic transmission. Based on planetary gear operating frequency analysis using PTA(planetary transmission analysis) program developed in 2012, It is expected that gear noise of the rear planetary gear set could be recognized easily in the concept design stage. Therefore, pRMC (planetary run many cases) analysis program that is developed in 2012 was applied to minimize the planetary gear noise level and noise distributions versus torque. To minimize noises coming from oil pump and final gears of a new transmission, several changes were applied, such as changing the clearance of double angular ball bearing, the oil pump rotor tooth number from 9 to 11 and the oil pump type from parachoid to megafloid and so on. Besides, stiffness values of the transmission case and the mount bracket were measured and reinforced properly. Finally, The total noise of the new FF 8th speed automatic transmission was developed successfully. Furthermore, E.O.L. testers also have been adapted to control the noise quality of automatic transmission assembly in the manufacturing factory. This paper could provide practical solutions to the automatic transmission NVH problems.