Hyun Ku Lee

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.

An Automated Design Search for Single and Double-Planet Planetary Gear Sets

Design of planetary gear sets is more involved than the design of their counter-shaft counterparts as it involves simultaneous design of a set of internal and external gear meshes while complying with a large number of systems and gear mesh related requirements for assembly, durability, noise, and efficiency. A manual iterative design process often results in suboptimal designs that fail to meet all these requirements simultaneously. In this paper, a methodology for an automated design search of single and double-planet planetary gear sets is proposed. With the input of a number of system-level constraints associated with the spacing and phasing of the planets, and acceptable ranges of basic geometric design parameters, this methodology defines a large design space in that a large number of geometric design concepts are identified and checked for any interferences. The external and internal meshes of these concepts are evaluated by using computationally efficient loaded gear tooth contact analysis model to predict their performance metrics such as transmission error amplitudes and contact and root stresses. They are then rank-ordered based on their performance metrics to identify balanced planetary gear set designs meeting all requirements equally well. At the end, results of an example design search were presented to demonstrate the effectiveness of the proposed methodology in defining a balanced solution that is acceptable in terms of all of its requirements.

Helicopter Rotor Load Prediction Using a Geometrically Exact Beam with Multicomponent Model

In this paper, an accurate structural dynamic analysis was developed for a helicopter rotor system including rotor control components, which was coupled to various aerodynamic and wake models in order to predict an aeroelastic response and the loads acting on the rotor. Its blade analysis was based on an intrinsic formulation of moving beams implemented in the time domain. The rotor control system was modeled as a combination of rigid and elastic components. A multicomponent analysis was then developed by coupling the beam finite element model with the rotor control system model to obtain a complete rotor-blade/control-system aeroelastic analysis. The rotor blade analysis was in good agreement and validated by comparing with DYMORE. Numerical results were obtained for a four-bladed, small-scale, articulated rotor rotating in vacuum and in a wind tunnel to simulate forward-flight conditions and its aerodynamic effects. The complete rotor-blade/control-system model was loosely coupled with various inflow and wake models in order to simulate both hover and forward-flight conditions. The resulting rotor blade response and pitch link loads are in good agreement with those predicted by CAMRAD II. The present analysis features both model compactness and robustness in its solution procedure while capturing the sophisticated behavior of individual rotor components. The analysis is expected to be part of a framework useful in the preliminary design phase for helicopters.

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.

Research for the Development of a pRMC Program for the Planetary Gear Noise

To design the optimized low noise planetary gear sets, a program called pRMC(planetary run many cases) is developed. The pRMC is especially using a combination analysis method for all gear specifications and also able to analyze any type of planetary gear sets. The pRMC is composed of the 5 sections those are generate, setting, evaluate, combine and analysis. After calculating all candidate gear sets, the pRMC could show many results that represent the character of each gear set including the transmission error which is the main gear noise factor, the contact ratios, the bending stress and so on. By comparing the results objectively, user could predict and select the optimized gear set which has quiet noise level and desired durability. The planetary gear designed by pRMC could have reduced noise and vibration level from 5 to 10 dB than previous-designed one.

A Design Framework to Improve the Dynamic Characteristics of Double Planet Planetary Gearsets

Double planet planetary gear sets have significantly more design options than their single planetary counterparts as the addition of the second planet set allows for greater flexibility in sizing and synthesizing transmission kinematic chains. Generally, the primary design constraints for these systems are based on transmitted load, speed ratio, and availability of space. However, once these specifications are met, few attempts are made to optimize the design any further as manual design techniques fail to assess all performance related aspects of the system. In this paper, a methodology to improve existing double planetary gear sets through adjustment of limited set of feasible design constraints is proposed. The improvement will be achieved through modifying the values of gear tooth profile shift, tooth thickness, and planet gear center distances. Design of experiments (DOE) approach is implemented to generate a finite set of models that accurately represent the entire design space. In order to investigate if the proposed alternative designs are an improvement from the baseline system, a finite element tool is used to model all of the potential configurations. The parameters that are used for the fundamental measurement of system performance in this study are bearing forces, gear mesh forces and transmission error spectra.

Research for a Development of the Test Equipment for Transmission Error of the Planetary Gear Carrier Pack

In general, there has been a lot of research concerned about the gear noise known to be proportional to gear transmission error for external gears likewise spur, helical gear, and hypoid gears. But, In the case of planetary gear set, gear noise study is insufficient because of the difficulty of designing, manufacturing, and understanding of its mechanical system. This study is aimed to develop the transmission error measurement equipment for the planetary gear sets used in the automatic transmission. By comparing the results of the transmission error and noise objectively, user could select the optimized planetary gear set which has quiet noise level before manufacturing the automatic transmission.

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

An Experimental Study and Analysis on NVH Behaviors of the Planetary Gear Set

ABSTRACT In this paper, Verification of the qualitatively identical relationships existing between simulation data and experimental results allowed for a new analysis procedure of a planetary gear set -- in an automatic transmission -- to be conducted. Tooth profiles were found to be crucial to the gear mesh forces of the planetary gear set. Based on Kahraman’s Model (8) , dynamic resonances of the planetary gear set were found to be out of operating range. Most importantly, a 2DPLANETARY FEM program, an innovative design tool for planetary gear sets, was utilized. * 기 호 설 명  : 각변위 K : 강성 I ce , I j : 극 관성모멘트 r : 기어 반경 E : 영계수 n : 모달인덱스 : 단위길이당 질량 I : 관성모멘트 1. 서 론 차량에서 발생하는 소음 중, 변속기에서 발생하는 기어 화인 소음(gear whine noise)은 약 200 ~ 4,000 Hz까지 광범위한 주파수 영역의 순음으로 구성되어 있다. 특히 자동 변속기의 주요 변속 장치로 †교신저자; 정회원, 현대자동차E-mail : hk-lee@hyundai-motor.comTel : (031)368-2380, Fax : (031)368-6095* 현대자동차사용되는 유성기어방식은 단순 축 기어 방식에 비하여 상대적으로 집약적이면서도 무게 대비 고용량의 토크를 전달할 수 있고 반경방향의 베어링 부하를 줄일 뿐 아니라, 소음도 적은 장점을 가지고 있다