듀얼 클러치 변속기 구조에 대한 설계 및 동적 성능 해석

Abstract

최근 자동차 업계의 전반적인 기술 개발동향을 살펴보면 장기적인 유가상승 추세와 선진국의 연비 및 배기가스 배출 규제강화의 영향으로 높은 효율과 더불어 친환경 차량의 기술 개발이 주를 이루고 있다. 이에 따라 연비를 높이기 위한 변속기의 성능 향상은 물론 구조에 따른 성능 비교에 대한 고찰이 필요하다. 본 연구에서는 수동변속기의 효율과 자동변속기의 편의성을 동시에 만족시킬 수 있는 DCT (Dual Clutch Transmission)를 장착한 차량의 구조에 따른 동적 성능을 비교하고 분석하였다. 이를 위해 차량의 powertrain은 engine, DMF (Dual Mass Flywheel), dual clutch, gear-box, synchronizer, drive axle 그리고 tire 등으로 구성하였으며, 각각의 modeling은 DCT의 작동 mechanism을 바탕으로 dynamics와 bond graph를 이용하여 상태방정식을 유도하였다. 두 DCT의 비교를 위해 velocity ratio를 동일하게 구성하였으며, 여기서 발생하는 gear ratio의 변화와 gear의 rotational inertia를 고려하여 modeling 하였다. 다음 modeling을 통해 유도한 상태방정식을 반영하여 각각의 module을 개발하였으며, 변속을 자동으로 수행할 수 있도록 3가지 mode (power, normal, economic)의 shift schedules과 shift control algorithm을 적용하여 Matlab/Simulink 기반의 DCT simulator를 개발하였다. 이후 변속시에 나타나는 DCT의 characteristics를 확인하기 위해 simulation을 수행하였으며, 구조가 서로 다른 두 DCT를 장착한 차량의 주행성능과 가속성능 그리고 연비에 대한 simulation 결과를 비교하고 분석하였다.|In recent years, the automobile industries concentrate on developing high efficiency and environmentally friendly vehicles due to the long term increase of oil prices and regulations for exhaust gas emissions. Vehicles equipped with DCT (Dual Clutch Transmission) are proposed as alternatives to improve both fuel efficiency and transmission performance by changing conventional transmission structures. In this study, the dynamic performance of the vehicles equipped with DCT satisfying both fuel efficiency of MT(manual transmission) and convenience of AT (automatic transmission) is investigated and compared using two types of structures. The state equations for DCT powertrain model consisting of engine, DMF (dual mass flywheel), dual clutch, gear-box, synchronizer, drive axle and tire are then developed using the bond graph method based on the DCT operating mechanism. The velocity ratios for two types of DCTs are set equal for comparison. The gear ratio changes and rotational inertia of the gear are also considered in the modeling process. Each module is developed based on the state equations derived from the powertrain modeling. The three shift schedule modes (power, normal, economic) and shift control algorithm are developed and applied for the gear shift of DCT. DCT simulator is then developed based on Matlab/Simulink. The simulation is conducted to investigate the driving performance, acceleration performance and the fuel efficiency of the vehicles equipped with two different types of DCTs during the shift. These are investigated and analyzed in the paper.; In recent years, the automobile industries concentrate on developing high efficiency and environmentally friendly vehicles due to the long term increase of oil prices and regulations for exhaust gas emissions. Vehicles equipped with DCT (Dual Clutch Transmission) are proposed as alternatives to improve both fuel efficiency and transmission performance by changing conventional transmission structures. In this study, the dynamic performance of the vehicles equipped with DCT satisfying both fuel efficiency of MT(manual transmission) and convenience of AT (automatic transmission) is investigated and compared using two types of structures. The state equations for DCT powertrain model consisting of engine, DMF (dual mass flywheel), dual clutch, gear-box, synchronizer, drive axle and tire are then developed using the bond graph method based on the DCT operating mechanism. The velocity ratios for two types of DCTs are set equal for comparison. The gear ratio changes and rotational inertia of the gear are also considered in the modeling process. Each module is developed based on the state equations derived from the powertrain modeling. The three shift schedule modes (power, normal, economic) and shift control algorithm are developed and applied for the gear shift of DCT. DCT simulator is then developed based on Matlab/Simulink. The simulation is conducted to investigate the driving performance, acceleration performance and the fuel efficiency of the vehicles equipped with two different types of DCTs during the shift. These are investigated and analyzed in the paper.