Analysis And Research Of Impact And Vibration Existing In The Powertrain Of Hybrid Electric Vehicle

With the problem of energy shortage increasing,"energy saving and environment protection"has become hot topic. Hybrid technology appears in this background. It effectively solved the problem of high emission and high fuel consumption in the traditional vehicle. Comparing with the conventional vehicle, hybrid electric vehicle has more complicated properties. According to the current research, the key technology of hybrid electric vehicle is consist of design and parameters matching of HEV, assembly technology of HEV and sophisticated energy control technology of HEV. In addition to focusing on the key technology of HEV, the impact and vibration which is brought by the special structure of HEV powertrain can not be ignored. This paper made an analysis and research on the impact and vibration existing in the powertrain based on the project of Geely Hybrid Electric Vehicle. The main works are as follows,Firstly, This paper made a brief presentation on the overall layout of the powertrain of LG-1A Hybrid Electric Vehicle, meanwhile gave a detailed explanation of the overall control strategy initial developed. It analyzes the portion of overall control strategy who affects the impact and vibration, and point out the direction of perfecting the control strategy, and then, figures out the main reason which gives rise to the impact and vibration in the powertrain.1,The powertrain is imposed a high resistance torque in a short time by the engagement of automatic clutch, which leads to the impact in the powrtrain. Also, it is the reason for rocketing of the longitude acceleration of the vehicle.2,The vibration of the powertrain is due to the torsion stiffness of the shaft between the engine and the automatic clutch just spent a small, meanwhile the slow damping and the lack of the flywheel of the engine is also the reason for vibration. Also, the vibration as isolation of the automatic clutch is closely linked with the work status.As the simulation technology plays an important role in modern science and technology research, therefore, the mathematics model of the powertrain is established, which offers the analysis tools for the project. This paper calculates the engine inertia via the method of identification and experiment, for the project encountered numerous difficulties such as the failure of offering of parameters from the company. Meanwhile, this paper gives an introduction of Unitire Model which is applied in the model of powertrain. It is said that the model is effective and reliable via the comparison between the simulation data and the experiment data.Finally, the automatic clutch engagement process, the separation process and the joint-driven process is studied and analyzed by the method of simulation and experiment. Firstly, the paper obtains the best parameter threshold of the impact response during the automatic clutch engagement process by subjective evaluation and experiment data. Then it optimizes the overall control strategy based on the threshold, which is certificated that the strategy is effective for solving the problem of impact during the automatic clutch engagement process. Meanwhile the paper concludes the best rule of engagement for reducing the impact according to the result of the simulation, whose reasonableness is validated by experiment. Next, the paper obtains the best threshold and engagement rule for solving the vibration during the automatic clutch engagement process via the same method. About the vibration during the separation process, this paper obtains the motor optimal separation speed under different gear based on a large number of experiments, and it will be realized on the test vehicle.