Koo-Tae Kang

An Experimental Study for Predicting the Planetary Gear Noise in the Vehicle

In this paper, various methods to improve the planetary gear noise in vehicles were introduced. Those cases of improvement have been used as good guidelines and references to prevent planetary noise problems. In this research, different types of planetary gear systems were also analyzed. The consequences of those analysis said in common that the planetary gear set generating noise mainly is the one which takes power directly from the turbine. Furthermore, a frequency versus vibration level map was introduced to judge how to solve the noise problem quickly in a vehicle development process. Besides, it is provided a predicting method which planetary gear set most contributes to noise problem taking in the vehicle and how to design the planetary gear set robustly.

A Development of the Noise Quality Checking System EOL of the 6th Speed Automatic Transmission in the USA

This paper shows a whole noise quality checking system for the new developed 6th speed automatic transmission manufactured in USA. Due to demand for manufacturing of the high NVH quality transmissions in the mass product line, some special checking system called EOL NVH is adapted. This EOL system is using vibration sensor and analysis technologies. Through adapting vibration analysis technologies and functions likewise RMS, crest factor, harmonics, peak, band and order tracking, various noise problems caused by wear, nick and deformations could be successfully detected and predicted. Therefore, automatic transmissions manufactured in the USA could get high NVH quality. The developing process described in this paper and results on EOL system will offer good guides to the engineers who built the next transmission factory.

The Mathematical Model on Crosstalk Effect of Airborne Noise Sources and Verification based on Comparison between Transfer Path Analysis Methods

In this paper, the mathematical model on crosstalk effect between acoustic noise sources is presented. Based on this model, a theoretical value to quantitate crosstalk effect of sources can be defined on the authority of reverberation property of surrounding which sources are located, relative magnitudes of sources and phase deference between acoustic wave transferred from all of sources. In order to verify crosstalk effect factor, experiments are made for two cases, weak and strong crosstalk effect condition, by using toro representative transfer path analysis(TPA) methods.

The Mechanism and Solution of Harmonic Gear Whine Noise in Automotive Transmission Systems

Since gear noise in automotive is one of the most unpleasant noises for passengers, various solutions, such as gear design optimization, tooth modification and transfer path reformations in the vehicle have been developed. But, these attempts are mainly focused on the fundamental mesh excitation of the gear set without any consideration of their harmonic noise (1st , 2nd or higher). Harmonic gear whine noise is easily audible in the vehicle because of their high frequency characteristics in spite of low sound pressure level. This annoying pure-tone noise is usually issued in the transmission system composed of the gears produced by grinding process. This paper will present the main sources of this harmonic gear whine noise with the test results of gears with identical design parameters but having different surface structure (roughness parameters, wave patterns). Additionally, manufacturing guidelines of gear surface structure will be proposed at the end of this paper.Copyright

Experimental and Analytical Approach for Identification of Driveline Clunk Source & Transfer Path

Driveline clunk is perceived as disturbing metallic noise due to severe impact at driveline components such as gear pairs when the engine torque is suddenly applied and transmitted to the driveline system. In this work, experimental method detecting the most contributive gear pair to the clunk generation was investigated and applied to mini van vehicle of front-engine and rear-wheel-drive. Another experimental method, TPA (Transfer Path Analysis), was employed to identify transfer path of the clunk. And then, driveline clunk model was developed using commercial multi-body-dynamics program, ADAMS, in order to further investigate the critical clunk mechanism and potential clunk reduction solutions by perfor ing parameter study.

Whine Noise Development of Engine Timing Gear System in Heavy Duty Vehicle

Gear train is the most applied in the heavy duty engine timing system on the benefit of reliability, durability, timing accuracy, maintenance, and high torque transmission. But the gear train is vulnerable to rattle and whine noise due to many serial gear connections, which lead to more possibility for gear backlash impact and gear transmission errors compared with chain and toothed meshed belt timing systems. Furthermore, normal heavy duty diesel vehicles like truck and bus are well vibration isolated from engine at gear noise frequency range. Therefore, noise source control is inevitable in the developing process in heavy duty diesel vehicles. The objective of this paper is to reduce timing gear whine noise in the engine developing process for heavy duty vehicles. Main focus is modification of gear tooth shape in the proto engine developing process considering vehicle driving modes. To investigate engine timing gear whine noise, transmission error analysis was executed in accordance with proto type gears and optimal gear tooth modification was induced by transmission error analysis, engine bench, and vehicle test.Copyright

An Experimental Research for the Optimization of the Gear Grinding Machine`s Operating Condition

ABSTRACT To improve the gear noise quality, gear tooth grinding machine are widely used in automotive industry. While using the gear profile grinding machine to improve the gear tooth quality of the transmission, several defects such as chattering, tooth waves that cause the gear noise occasionally happened. But it is very difficult to solve that problem, because there is no one who knows the setting up the optimal grinding condition appropriately. The abnormal manufacturing conditions which make the gear noise make the engineer to spend a lot of time, effort, and money. Due to demands for solving the serious abnormal gear noise happened in the automatic transmission in the mass product stage, the vibration checking process in the worm wheel axis, work rotation and fixed axis of the grinding machine were adapted to find the root causes. As a result, gear profile wave are affected by the work rotation axis’s unbalance which is caused by worm wheel feeding speed. And a primary and the secondary grinding feeding speed, cutting oil, work fixed forces are also proved as the important factors. After setting up the grinding condition reported in this paper, it was adapted successfully to the grinding machine to manufacture the new automatic transmissions’ gear. The gear noise was dramatically disappeared and the process and the results will offer good guides to the engineers who manufacture the gear with the grinding machine.

A Research for the Planetary Gear Noise Development in FF 6th Speed Automatic Transmission

In order to improve the planetary gear noise of the new developed 6th speed automatic transmission, it needs to understand noise mechanism. Basically, many transmission’s components have an effect on the gear noise. In this paper, planetary gear noise sources which are influenced by gear tooth shapes and backlash among the gears, position of pinion gears, and misalignment of the sun gear are studied and experimented. Also, transfer-path likewise one-way clutch contacted between the carrier and case, and valve-body covers are also researched to reduce the transferred vibration and radiated noise levels. After developing the planetary gear noise, its evaluation specification is adapted to EOL (end of line) equipment to check the transmission’s noise quality in the factory.Copyright

A Development of an Intake RCV System for the Low Noise Turbo Engine

In this paper, an intake RCV system for low noise turbo engine was developed through optimization process of a geometric path of compressor housing and an open rate of recirculation valve. At first, the critical customer requirement from voice of customer was defined and quality function deployment of an intake RCV system was executed. And then, the renovative concept design using pugh matrix method was selected as final concept for satisfaction of requirement. Simultaneously, system analysis was carried by function diagram and fishbone diagram. Next, control factors and levels for the optimal design were performed. And, the optimal design of an intake RCV system was studied using design of experiment. Conclusively, we achieved not only cancellation tip-out noise at the driving condition but also improvement of NVH commodity through optimization process of an intake RCV system, which is optimal configuration of compressor housing and recirculation valve.

A Study of Improvement on the Torsional Vibration of Input Shaft and Structural Vibration of Vehicle Using Tunable Dual Stiffness Type Clutch in Auto-transmission

According to torsional vibration characteristic of a tunable dual stiffness type clutch(TDSTC) in auto-transmission, the input shaft system have occurred breakdown for the duration cycle and over-vibration happened on vehicle at specific condition. This paper introduces the improvement of the torsional vibration of input shaft and the vehicle vibration by tuning of the TDSTC.