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습식 DCT(Dual Clutch Transmission) 클러치 팩 내부에서의 체결 동작에 따른 변속기유 거동 연구
김우정(WooJung Kim),이상호(SangHo Lee),장시열(Siyoul Jang) 한국트라이볼로지학회 2017 한국윤활학회지(윤활학회지) Vol.33 No.3
This work studies the flow behaviors in the gap between the friction pad and separator in wet-clutch systems. The fluid volume of the lubricant is modeled using the entire system of wet-clutch pack of a dual clutch transmission that has larger outer radius of odd gear shifts and smaller inner radius of even gear shifts. Flow behaviors in the gap of the clutch pad are computed using the gear shift modes that consider the real relative velocities between the friction pad and separator. Flow behaviors in the gap of the disengaged clutch pad are mainly investigated for the wet-clutch system, whereas the engaged clutch pad is modeled with no fluid rate through the contacting surfaces. The developed hydrodynamic fluid pressures and velocity fields in the clutch pad gap are computed to obtain the relevant information for managing flow rates in wet-clutch packs under dual operating conditions during gear shifts. These hydrodynamic pressures and velocity fields are compared on the basis of each gear level and gap location, which is necessary to determine the effects of groove patterns on the friction pad. Shear stresses in the gap locations are also computed on the basis of the gear level for the inner and outer clutch pads. The computed results are compared and used for the design of cooling capacity against frictional heat generation in wet-clutch pack systems.
김해용(HaeYong Kim),장시열(Siyoul Jang),김우정(WooJung Kim) 한국트라이볼로지학회 2014 한국윤활학회지(윤활학회지) Vol.30 No.5
Frictional heat greatly influences the friction behaviors during clutch engagement. Therefore, the engagement of a wet or dry clutch is frequently not under control by the frictional heat. In a wet clutch, the frictional temperature also specially needs to be controlled, and in many cases, the clutch material is selected to prevent a temperature rise from the friction between friction pad and separator. However, only the selection of the clutch material cannot ensure sufficient control of the temperature rise by the friction. The groove pattern on a friction pad is designed for more flow rates of transmission fluid between the contact gap of clutch pad and separator for the cooling effect. In this work, grove patterns are designed for more flow rates out of the contact gap between friction pad and separator plate. Selected groove design shows the improvement flow rates of transmission fluid through both inner and outer radius, where most of the transmission fluid flows through the outer radius when the clutch is engaged due to the centrifugal force in conventional wet clutch groove. Several comparisons of the amounts of frictional heat generated on clutch pads are made in order to verify the decrease of the temperature rise according to the flow rates along the groove patterns.
영구자석 동기전동기 능동단락 회로 동작에 감자해석 관한 연구
유회총(Huai Cong Liu),김우정(WooJung Kim),문종주(JongJoo Moon),안일환(Il Hwan An) 한국자동차공학회 2022 한국자동차공학회 학술대회 및 전시회 Vol.2022 No.11
This paper investigates the behavior of active short circuit(ASC) in order to protect and inverter and a motor when any faults occur on inverter system at high-speed operation region of motor. The implementation of ASC function is to control the inverter output to be a zero vector which state can be named three phases short(3PS) in the fault condition. The ASC function causes unintended brake torque in the motor and the freewheeling current between the inverter and the motor which is called ASC-current. In general, the ASC current will be several times higher than the maximum power current. Therefore, the magnets selected for the motor design must ensure that they will not be demagnetized under the ASC current. This paper introduces an 8-pole 100kW permanent magnet synchronous motor, discussed the maximum current value of the motor in ASC state, and conducts finite element analysis of demagnetization through dynamic and static methods to verify the safety of permanent magnet selection.
습식클러치 패드의 Groove 패턴에 의한 변속기유의 동적 거동
김해용(Hae Yong Kim),장시열(Siyoul Jang),김우정(WooJung Kim),신순철(Soon Cheol Shin) 한국트라이볼로지학회 2014 한국윤활학회지(윤활학회지) Vol.30 No.2
Transmission fluid film behaviors in the gap between the wet clutch pad and separator plate are analyzed using the CFD software ADINA. Three pattern groove designs are selected and are used to validate the fluid film behaviors based on the outlet flow in the gap when the wet clutch pad and separator plate are engaged. The main design goal for pattern grooves is faster engagement. In most cases, much of the outlet flow of transmission fluid in the gap occurs on the outer radius boundary due to the centrifugal force generated by the clutch pad circular motion. Groove patterns are created to ensure faster transmission fluid outlet flow in the direction of the inner radius boundary. Computational results of the selected groove patterns are compared.
파형 습식클러치의 드래그 토크 저감을 위한 파형내 유로 위치 설정 설계 연구
조정희(Junghee Cho),한준열(Juneyeol Han),김우정(Woojung Kim),장시열(Siyoul Jang) 한국트라이볼로지학회 2017 한국윤활학회지(윤활학회지) Vol.33 No.1
Drag torque reduction in a wet clutch pack is a key aspect of the design process of the dual clutch transmission (DCT) system. In order to reduce the drag torque caused by lubricant shear resistance, recently developed wet clutch pack systems of DCT, as well as automatic transmission and other four-wheel drive (4WD) couplings, frequently utilize wavy wet clutch pads. Therefore, wavy shape of friction pad are made on the groove patterns like waffle pattern for the reduction of drag torque. Additionally, the groove patterns are designed with larger channels at several locations on the friction pad to facilitate faster outflow of lubricant. However, channel performance is a function of the aviness of the friction pad at the location of the particular channel. This is because the discharge sectional area varies according to the waviness amplitude at the location of the particular channel. The higher location of the additional channel on the friction pad results in a larger cross-sectional area, which allows for a larger flow discharge rate. This results in reduction of the drag torque caused by the shear resistance of DCTF, because of marginal volume fraction of fluid (VOF) in the space between the friction pad and separator. This study computes the VOF in the space between the friction pad and separator, the hydrodynamic pressure developed, and the shear resistance of friction torque, by using CFD software (FLUENT). In addition, the study investigates the dependence of these parameters on the location and waviness amplitude of the channel pattern on the friction pad. The paper presents design guidelines on the proper location of high waviness amplitude on wavy friction pads.