| Engineering vehicles usually refers to self-propelled construction machinery, which is widely used in mining, construction, railway, highway, national defense, ports and so on. It can reduce the engineering cost and shorten the project cycle,etc. Engineering vehicles in the traction operation is mainly in off-road. Bad working environment, big and uneven load, the unsufficient engine power and the limited strength of the actuator are its features. Moreover, while the driver is driving the vehicle, he has to simultaneously complete the control of the work device and frequently shifting.etc, which increases the intensity of labor. Therefore, it’s significant to give full play to the working performance and automatic operation performance of engineering vehicles.The main research object of this paper was from the cooperation projects of Continuously Variable Transmission (CVT) project of Northeast University, Shengyang Yueshida CVT Co.Ltd and Dongfeng Company. Taking the Dongfeng agricultural machinery product-wheeled tractor 1804 as the research object, the performance of mechanical parts was been understand, and the drive system, which used the STC microcontroller as the microprocessor controller, was been set up to meet the control requirements. Through measuring and analyzing the experimental data, finally, a pure electric continuously variable transmission which could deliver large load was developped.The transmission in this paper is used only for the function test and experimental research, which is not made into product. Based on this, developping the controller can match the transmission, which is also the first exploration of the controller productization. Therefore, having the experimental study on transmission, if the study and application achieve success, its significance is far-reaching significant.To research of the controller, this paper has cleared the structure function of mechanical components, the transmission mechanism and action process, and determined the control strategy. The main experimental idea of the controller is to combine the control of software and hardware driver fully and effectively. The compiled environment of software is based on Keil software, which is programmed with C language, to control the machine main body to complete the target action effectively, flexibly and controllably. The hardware section takes STC12C5A60S2 microcontroller as the microprocessor. Through building the control system, building a backward channel and connecting the driver circuit, the input signal can be received by the microprocessor effectively and correctly. According to the control requirements and control purposes, cooperating forward and backward drive circuit to drive motor and control CVT to realize the automatic conversion. Firstly, after finishing control mainframe, the calibration test is done. The experimental bench is set up to do the field test and obtain the experimental data, And then the experimental data is used to accurately describe the curve of the speed ratio change. The curve of the speed ratio change is transformed into digital signals and the program language is modified accurately to make it consistently with gear change request to meet the control requirements. During the hole experimental process, hardware and software need cooperate with each other to directly collect the control signal. Feedback logical thinking is applied to control the drive motor. The hole process finished the development of the pure electric control for tractor’s drive controller and experimental research.The transmission uses friction drive to achieve the large load transmission, and the controller also has the good ability of control response and follow, They realize the function of multi-position control and continuous control requirements. |
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