| High transmission efficiency and good shift smooth are the developing trend of gearbox. AT has an excellent shift smooth and advanced technology, but its intrinsic drawback is low efficiency due to using hydraulic torque converter. The virtues of AMT are simple structure, high efficiency and low cost, but the traction interruption is its inevitable disadvantage that leads greater shift jerk, result in a bad shift quality. Recently people are increasingly interested in a new type of automated transmission termed as DCT and it will be the next generation of gearbox, which bridge the gap between automated manual transmission (AMT) and conventional automatic transmission (AT). DCT can be regard as a betterment of AMT, and be simply explained as following: it is composed of two manual transmissions (MT), one for odd gear such as 1st, 3rd and 5th, another for even gear such as 2nd, 4th and 6th, each transmission has its own clutch and output shaft, they are connected with one common output shaft via gear stage and are coupled to engine by twin clutches individually. Its structure is simpler than that of AT which is built up with planetary gear sets. Without of torque converter which is a complex and low efficient part of AT will make for high mechanical efficiency. DCT can achieve powershift without traction interruption during shift process, compared with AMT, DCT will have a better shift quality. Now DCT is the hotspot in the research field of automatic transmission.There are two kinds of clutch used in DCT, one is dry clutch, the other is wet clutch, this paper use wet clutch for example, based on comprehending the mechanism of DCT, aim at its work characteristics to study the integrated control strategies systemically based on dynamic simulation technologies of the driveline with DCT. The main contents include: dynamics analysis of powertrain with DCT, Analysis of clutch friction characteristic, the principle for judging the clutch work state such as slipping and sticking, simulation controller design of clutch and engine, a dynamic model of the powertrain with DCT has been established with Matlab-Simulink, the integrated control strategies of the overlap control between twin clutches and engine during gear shift, finally the simulation result is shownand analysed in depth.There are six parts in the dissertation. The first part introduces the structure, work principle, development process and development foreground of double clutch transmission, summarizes the merit and study meaning of double clutch transmission. This chapter finally analyse the characteristics and development trend of wet clutch.In the second chapter, the detailed structure of wet double clutch is introduced. The contents include: front cover, inner cover of outer clutch, inner cover of inner clutch, steel flake and frictional flake of outer clutch, steel flake and frictional flake of inner clutch, balance piston, work piston and replacement spring of inner clutch, outer cover of inner clutch, replacement spring and work piston of outer clutch, snout and bush. Besides, the work principle of wet double clutch is analysed, three kinds of work process of wet double clutch is introduced. In the third chapter, the friction material, friction type and lubrication mechanism of wet clutch is introduced. There are three stages in the engagement of the wet clutch: squeeze, compact and rough. The main capability parameter and invalidation form of wet clutch is reckoned. Capability parameter include: engaged time, friction power, increase of clutch temperature, abrasion rate. Invalidation form include: minimum friction torque, resistive capability of agglutination, resistive capability of abrasion, pressure condition. Finally the main dimension and hot burthen of clutch is reckoned.Dynamic simulation model of the driveline with DCT is built in the fourth chapter, dynamics analysis of powertrain with DCT, dynamics equation and system model of double clutch based on three different kinds of work pattern is introduced. Analysis of clutch friction characteristic, the principle for judging the clutch work state such as slipping and sticking, a dynamic model of the powertrain with DCT has been established with Matlab-Simulink, simulation controller design of clutch and engine in the end.In fifth chapter, the simulation result is shown and analysed in depth, the shift process and shift control strategy is analysed. Finally, the integrated control strategies of the overlap control between double clutches and engine during gear shift is analysed.The last chapter summarizes the whole paper. Introduce the main work and research result and the next research direction.Simulation technologies are playing more and more important roles for shortening development period and economizing development expenses in automotive industry. Due to the virtues and great market foreground of DCT, recently a lot of studies on powertrain simulation, control strategies and structure design have been done and have got a common know that the overlap control strategies of the twin friction clutches is the most difficult technology and the smooth control is the main reason for prolonging it to popularize to other type vehicles. The systematic analysis of the powertrain dynamic characteristics, reasonable evaluating system for shift qualities and comprehensive identification of the factors which affect the shift quality mainly are the key for solving the problem. |
