• 대한기계학회논문집A
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• 제38권4호
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• pp.393-400
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• 2014

본 논문에서는 실제 자전거 주행에 적용 가능한 자동변속장치를 개발하기 위하여 자전거용 변속장치 중 내장기어허브를 이용하여 자전거 자동변속장치를 개발하였다. 개발된 자동변속장치는 주행 중 페달rpm과 주행속도를 측정하여 자동변속을 수행하며, 최대심박수의 ~80% 부근에서 ~150W정도의 주행출력을 낼 수 있는 일반적인 이용자가 사용가능하도록 개발되었다. 서울시 한강변 자전거 주행로의 경사를 구현한 실내주행 실험결과 자동변속장치는 자전거 주행시 이용자의 페달rpm을 적정한 수준에서 유지하도록 변속을 수행하였으며, 자전거 이용이 서투른 이용자도 적정한 페달rpm을 유지하며 주행할 수 있었다.

• 대한기계학회논문집A
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• 제26권5호
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• pp.822-827
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• 2002

In general, jerk phenomenon appeared because of gear changing, when a vehicle starts off or climbs an incline. Therefore, it makes ride quality worse. In this paper, an optimal pattern of automatic transmission was designed using fuzzy logic in order to improve ride quality. After del eloping fuzzy rule for shift pattern control of automatic transmission, dynamic characteristics (i.e. acceleration, velocity, distance and so on) were simulated using dynamic model of a car. To do this he powertrain model of a vehicle with automatic transmission including torque converter, gear box, and final gear drive - from engine to tire - is developed.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2000년도 제32회 추계학술대회 정기총회
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• pp.273-279
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• 2000

Until recently performance requirements for automatic transmission fluids have continued to change to reflect the design changes of automatic transmission. The major purpose for these design changes is to improve the fuel economy and easy driving. To meet recent performance requirements fur automatic transmission the needs for special base oils Bike API Group III and IV base oils become larger. In this paper to evaluate the effects of base oils on performance of automatic transmission fluids formulated with API Group I,II,III and IV and Dexron III and Hereon Type additive package, Brookfield viscosity, oxidation test, SAE No.2 friction test and seal compatibility test were examined. From the test we knew that the use of Croup III and IV base oils in ATF has several benefits in low temperature viscosity, oxidation stability and SAE No.2 friction characteristics.

• 한국기계가공학회지
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• 제20권3호
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• pp.40-46
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• 2021

An automatic transmission of automobiles enables comfortable driving experience with lower transmission shifting jerks. However, the assembly structure is more complicated and requires additional components with lower efficiency than the manual transmission system. Extensive research has been conducted to improve the overall transmission efficiency by optimizing each component of the automatic transmission assembly. This study focuses on enhancing the friction torque of double angular contact ball bearings used in automatic transmission. The friction torque of the bearing varies with the operating conditions such as the operational load and rotating speed. Since reducing the friction torque of the bearing tends to deteriorate the durability of the bearing, it is necessary to design the bearing having a minimum required friction torque by determining the durability life of an automatic transmission assembly, In this study, the theoretical life and friction torque of conventional and newly-developed bearings are calculated. The difference in the friction torque between the new and existing bearings are also evaluated.

• 산업공학
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• 제14권2호
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• pp.134-139
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• 2001

This paper describes an automatic design system for the parts that compose the power transmission. Power transmission is composed of shaft, gear, clutch, brake and housing. To design power transmission, there are many recurrent calculations and drawings needed with conventional design process. In this paper, we propose three dimensional automatic design system that reduce recurrent calculations and drawings. Developed system consists of two modules; 1) Design expert system module to assist determining design parameters of clutch, brake and gear. 2) Parametric modeling module to make three dimensional solid model automatically. The proposed system has been tested in the fields and found to be a useful system.

• 한국소음진동공학회논문집
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• 제26권5호
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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.

• 한국자동차공학회논문집
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• 제5권3호
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• pp.172-181
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• 1997

The dynamic characteristics during gear ratio change including the disturbance of output torque has been one of the most important issues in the study of automatic transmissions of passenger cars. In this paper, to investigate the dynamic characteristics of a passenger car automatic transmission during gear ratio change, a dynamic model of the driveline of a passenger car focused on the automatic transmission is proposed and the dynamic simulation program is developed. The results of the simulation show good agreements with the experimental data, which process the use fullness of the dynamic model and the simulation of the driveline.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2001년도 춘계학술대회 논문집
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• pp.267-270
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• 2001

A lot of efforts have been made to analyze the performance of the vehicle equipped with automatic transmission through simulation. It might be necessary to understand the different types of transmissions, i.e., different power flows, for different models. If there is a module that can be applied to different types of automatic transmission, it could be helpful to transmission-related engineers. This study has started up from this idea. The common bond graph has been obtained from several types of the automatic transmission. The overall generalized equations and kinematic constraint equations have been derived using virtual power sources on common bond graph. They are used to derive state equations and constraints. These equations have been applied as an application to the vehicle equipped with two simple planetary gear set type of Ravigneaux gear type automatic transmission. The state equation, kinematic constraints, and dynamic constraints have been derived in every gear and shift operation using overall generalized equations and kinematic constraint equations. Simulations for constraint speed running, standing-start running, rolling-start running, and LA-4 mode have been conducted to analyze the performance of the vehicle powertrain using GVPS(Generalized Vehicle Powertrain Simulation) program wit pull down menus.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2012년도 추계학술대회 논문집
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• pp.544-545
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• 2012

In recent years, vehicle manufacturers have steadily developed fuel saving technologies such as multi-speed automatic transmission. With such a background, the Hyundai-powertech have developed the new 6-speed rear wheel drive(RWD)automatic transmission for FR vehicles. Despite having six-speed, it has the same number of planetary gears as a previously used five-speed automatic transmission and fewer brakes and one-way clutches than the 5 A/T, meaning that it is light, compact, and inexpensive. But, in addition to meshing this internal and external gear simultaneously and phase difference by the tooth contact point and the time difference occurs asymmetric and symmetric sideband noise and vibration caused by the modulation in the vehicle. In this paper presents a method for the design of the carrier phase difference by developing various theories and experiments for gear noise.

• 한국기계가공학회지
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• 제18권11호
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• pp.24-34
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• 2019

An automotive automatic transmission is a popular power-transmitting device in passenger vehicles, as it provides various speed ratios for diverse driving conditions with easy manipulation and smooth gear shifting. The transmission is mainly composed of input and output shafts, planetary gear sets, brakes/clutches, and housing, and it yields multiple forward gears and one reverse gear by actuating the shifting devices of the brakes and clutches. In developing a new transmission, kinematic configurations of a transmission, which presents a brief structure and actuation schemes for speed ratios, need to be checked to determine if the structure can be assembled in a layout. It is impossible for a transmission concept having any interference in connecting main components to be developed further in the design process, since connection interference leads to failure of a layout design in the 2-D plane. In this research, an analysis of the assemblability of a front-wheel drive automatic transmission is carried out on an example concept design by applying the vertex addition algorithm based on graph theory.