| With its high fuel efficiency and simple structure,the dry dual clutch automatic transmission(DCT)occupy the certain position of the market.However,the development of traditional hydraulic system of dry DCT is severely restricted by its low energy utilization,complex hydraulic system,poor starting and shifting performance.Therefore,the development of low energy consumption,high efficiency and high reliability hydraulic system of dry DCT has important theoretical significance and engineering application value.This paper presents a new hydraulic system of dry DCT.For the oil supply system,an electric motor is used,and work together with hydraulic pump and accumulator;For the hydraulic oil circuit,it reduces the number of solenoid valves,simplifies the system oil circuit and reduces the cost;First,For clutch control,displacement control mode is used for odd gear clutch K1 and pressure control mode is used for even gear clutch K2.Aiming at the displacement control scheme of clutch K1 of the dry DCT,a mathematical model is established and simulated.The stability,step and sinusoidal response characteristics of the system are analyzed.Then,according to the working status of clutch K1,K2 kiss point and slip point during the shift of DCT,it is divided into 5 working stages,and the dynamic mathematical model of each stage is established according to its dynamic characteristics.Through the PID step response control,the shift characteristics of DCT and the control characteristics of different control modes of clutch K1 and K2 are analyzed.By comparison,the response characteristics and anti-interference performance of clutch K1 displacement control scheme are better than that of clutch K2 pressure control.In addition,the relationship between the stiffness and displacement accuracy of the reset spring of the shift valve and the response of the displacement of the shift valve to the pressure of PPV1 are analyzed.The pressure variation characteristics of motor,quantitative pump and accumulator oil supply system are analyzed.Finally,a new DCT AMESim simulation model is established,and the changes of speed and torque in the process of shifting of the gearbox are also analyzed,and the characteristics of the torque speed of the clutch and the gearbox,under the different torque overlap in the process of shifting.The new dry DCT designed in this paper has good shift characteristics,simplifies the system structure and improves the working efficiency of the hydraulic system.It effectively solves many problems existing in traditional dry DCT,brings certain economic benefits to enterprises and society,and also provides technical support for the promotion and development of dry clutch. |
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