| Because a CVT has a simple structure, low cost, long service life and its speed ratio is continuous in a designed range, drivers are free from the problem of shifting impact when driving vehicles with CVT. Theoretically, as there is no speed fluctuations caused by shifting and the engine operates in an ideal working mode, it is easy to realize a integrate control of the power transmission and to fully exert the engine's characteristics for higher fuel economy, higher power, comfort of driving and steering smoothness. Therefore, foreign manufacturers are applying themselves to the research on integrate engine and CVT control technology.A vehicle with CVT made by Nanjing Fiat Co. Ltd is chosen for the research on comprehensive engine and CVT control in the typical operating conditions of up and down a slope.The main work includes:1. Study of a integrate engine and CVT control down a long slope: Research is made on integrate control of power transmission to fully utilize the engine's assistant brake capability as the vehicle down a long slope. An engine's brake torque curve is obtained through trials. Double-mass inertia model for a vehicle up and down the slope is established. A integrate control strategy of the engine and CVT in the above operation conditions is proposed. The mathematics softwares MATLAB and SIMULINK are used to make simulations.2. Study of a integrate engine and CVT control up a slope: On the basis that the power is fulfilled as the vehicle up a slope, research is made on integrate control of power transmission to better fuel economy. Engine universal dynamics and economic speed regulation characteristics are obtained by trials. Double-mass inertia model for a vehicle moving up the slope is established. Integrate control strategy of the engine and CVT of the vehicle ascending the slope is proposed. The mathematics softwares MATLAB and SIMULINK are used in this paper to make simulations.3. Establishment of an automobile dynamic simulation test platform: Automobile dynamic simulation test platform is built and the power transmission train of the vehicle's CVT is installed. The software and hardware of CVT controller is designed. In the mean time, this paper exploits the interface of the trial platform, which is based on the virtual instrument of LabView, to adopt the visualization technology to monitor the control results of the trials.4. Actualization for vehicles in driving operation on the dynamic simulation test platform: The method of simulation is studied to simulate the vehicle down a long slope and up a slope on test platform. Firstly, force analysis of the vehicle while moving up and down the slope is done. Secondly, force analysis is done on the test platform. For the test simulation down a long slope, the engine is considered as the load and the working state of a direct current generator as an electromotor. Force analysis is done on the test platform, and the simulation method on the test platform for dynamic simulation using a direct current generator is obtained. For the test simulation up the slope, the engine is giving a driving force and the DC generator is considered as the load, which is now generating electricity. Force analysis is done to the test platform, and the simulation method on the test platform for dynamic simulation of the vehicle ascending the slope using a DC generator is obtained.5. Study of trials on the integrate control of engine and CVT as vehicle drives on slope: This section mainly includes trial research on the c integrate control strategy of engine and CVT.The main innovations of this thesis include: 1. Proposing integrate control strategy of engine and CVT for vehicle down a long slopeSustained braking system should be used in order to improve the safety of automobile moving down the slope. The former researches shows that: no matter what kind of sustained braking method adopted separately, stable speed state down the slope can not be realized because of the limited gear lever of the transmission. Generally, the combined functions of halting the engine, shutting off the exhaust-port and retarded braking can stabilize the vehicle speed as it descends the slope. However, because of the additional braking system, not only is the cost increased, but also the control system is more complicated. Because of these problems, this thesis proposes the engine and CVT integrate control strategy which makes use of the characteristics of continuous variable transmission and the capability of the engine sustained braking for the first time. At the same time, the double-mass inertia model which is established in the transmission system fills up a blank space in the research of CVT. In addition, the combination of the engine braking and CVT fully shows the advantages of the CVT technology.2. Proposing integrate control strategy of engine and CVT for vehicle up a slopeIn former studies on the integrate control strategy of power transmission on vehicles with CVT, drivers should choose the operation mode(power mode/economy mode), and that has a affection on vehicle control. This thesis proposes the integrate control strategy of power transmission for vehicle up a slope, which can confirm the engine's driving torque and option of operation mode through the manipulation of accelerograph pedal, and improves the fuel economy and control effect of entire vehicle on the basis that the power of vehicle is fulfilled.3. Establishment of the dynamic simulation test platformIn former test platforms, chassis dynamometer test platform is used at the demand of dragging operation conditions and load increase state, but the cost is terribly high, and the entire car should be placed in the test platform, but it's of no benefit to the research. Considering all of this, the dynamic simulation test platform can be established using a DC motor which can not only be loaded but also dragged. At the same time, the simulation method of the operating conditions (up and down the slope) has been studied. From the study, the control methods and equations using the DC motor to load and drag have been found .This study has laid the foundation for the application of the DC motive used in the test platform.
|
PDF Full Text Request