At present, the most representative hybrid electric vehicles are Toyota hybrid electric vehicle and general dual-mode hybrid electric vehicle. However, because Toyota hybrid electric vehicle has the deficiency of low transmission efficiency of the whole transmission system when driving at high speed, although general dual-mode hybrid electric vehicle improves the transmission efficiency of the transmission system, it has the problems of complex mechanical structure and high cost.
In response to these problems, a Chinese company stepped onto the historical stage of hybrid vehicles at the time when Toyota of Japan vigorously promoted dual engine hybrid to the Chinese market. Since its establishment, the company has received a large number of financial support at the level of national enterprises. Compared with the traditional gear transmission system, the planetary gear transmission system has the advantages of small volume, light weight, compact structure, large bearing capacity, high transmission efficiency, large transmission ratio, reliable movement, strong impact and vibration resistance. Its most significant advantage is that the power can be split when the system is driven. Therefore, in various mechanical transmission systems, planetary gear transmission has become the primary choice of gear transmission devices in the system, such as heavy-duty transport aircraft, oil and weapons, as well as the gear transmission device of vehicles requiring differential. Based on these advantages, the company adopts planetary gear mechanism in the gear transmission system of hybrid electric vehicle, and puts forward a new hybrid power split transmission system scheme under the condition of effectively avoiding the patent of Toyota hybrid electric vehicle.
The power transmission system of the hybrid electric vehicle takes the engine and large and small motors as the power source of the system, and the gear transmission system is composed of composite planetary row mechanism and parallel shaft gear mechanism. Although the power transmission system of the hybrid electric vehicle improves the transmission efficiency of the whole system, compared with ordinary vehicles, multiple power sources of the hybrid electric vehicle make its power transmission system have a variety of driving modes, It makes the vibration characteristics of the whole system more complex. The transmission power of the system is increasing and the gear speed is accelerating. The vibration and noise of the power transmission system of hybrid electric vehicle has become a thorny problem. Dynamic excitation is the root cause of vibration and noise caused by the transmission system. When the hybrid electric vehicle is driving, the power transmission system has the intervention of external excitation and the internal excitation between the gears in the system. These two kinds of excitation belong to dynamic excitation. The stiffness excitation in the internal excitation is periodic excitation, which has the characteristics of mutation and time variability. It is caused by the change of the number of meshing teeth in the process of tooth meshing in the system. Error excitation is also a kind of internal excitation, which is mainly caused by the geometric error of gear transmission system in manufacturing and assembly. In addition, due to the need of lubrication and the manufacturing accuracy and installation error of gear teeth, the tooth side clearance in the system can not be avoided. In the gear transmission system of hybrid electric vehicle, under the condition of high speed and light load, the tooth side clearance in the composite planetary gear system will have an important impact on the dynamic characteristics of the system. This “vibration impact” problem caused by clearance has a serious impact on the service life and reliability of gear transmission system. Based on the above characteristics, the gear transmission system of hybrid electric vehicle is a typical nonlinear system. The research on the nonlinear dynamic characteristics of the system is of far-reaching significance to the vibration and noise reduction of the gear transmission system of hybrid electric vehicle.