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Compared with the traditional vehicle drivetrain system, the electric drive system is characterized by one or two transmission ratio, higher maximum speed and faster torque response. Therefore, NVH problem of electric drive system is more complex. In the development of electric drive system, NVH problems caused by structural vibration, especially the torsional vibration, are easy to occur and difficult to solve. The purpose of this study is to further study the structural characteristics of the electric drive system and its response characteristics under various vibration excitations. The research object is an electric drive system under development, which adopts two-stage and fixed ratio transmission, the maximum speed is 12000 rpm. In the on-vehicle test, an unbearable noise has been found in this system under certain running condition. According to the NVH measurement result, this noise was caused by the system resonance at a certain frequency.

With the continuous development of various technologies in the field of electric vehicles, more and more mature products are put into the market. Among them, electric commercial vehicle has been supported by many preferential policies because of its wide use and high energy utilization and has developed rapidly in recent years. At present, the electric drive-train systems of commercial vehicles can be divided into motor direct drive, integrated el-axle and distributed e-wheel drive. The first type only uses motor to replace the engine, and the other parts have little change. This method has low transmission efficiency and loose structure, which is a temporary transition scheme. The drive types of integrated E-axle and distributed E-wheel have their own advantages and disadvantages, which way to become the mainstream of the future have not yet been decided.

In recent years, with the rapid development of automobile industry, especially the vigorous promotion of new energy vehicles, CAE simulation analysis technology plays an increasingly important role. Differential is a key component of vehicle drive line system, its main function is to meet the different demands of the wheels on both sides when turning. The differential is composed of differential case, planetary gears, planetary gear shaft and half-shaft gears. Because of complex working conditions and poor stress environment, fatigue damages are easily occurred on these components. If the fatigue life of differential can be predicted by simulation analysis technology, it will provide a basis for vehicle design, which will reduce the cost of practical test. In addition, the structure can be optimized by simulation analysis, so as to improve its performance and fatigue life. However, the structure of differential is complex, and it is difficult to analyze its fatigue life.

Vehicle gearbox whine is a common NVH problem which may directly cause complains from passengers on the quality and performance of vehicle. In order to efficiently and fundamentally control the whine phenomenon, this work first studied the characteristics and mechanisms of the gearbox vibration and noise. The study results revealed that the transmission error of gear was the excitation source of gearbox vibration, and the ambient air was the main transfer path of radiation noise. Then a multi-physics coupling simulation model was built to reveal the interactions among gear, housing and ambient air. This model could also predict the characteristics of the sound field near the passenger’s ear. To take account the psychoacoustic property of human auditory system, this work applied a quality index called tonality to evaluate the severity of gearbox whine. This paper also describes a case study to verify the accuracy and availability of the simulation model.

In the driveline system of all-wheel drive or rear-wheel drive vehicle, drive axle is a major transmission component. Within the perspective of noise and vibration, drive axle is not only a transfer path of the excitation from engine, but also an excitation source because of the engaging movement of its inner gear sets. As a precision assembly, the design parameters and manufacture processes of drive axle have a great impact on the NVH performance of vehicle. This paper proposes a workflow and a cascaded targets system for NVH development of vehicle drive axle. In order to efficiently and fundamentally control the NVH performance related to drive axle, this work first studied various kinematical and structural characteristics of component parts to conclude the key design parameters.

The vibration isolation performance of vehicle powertrain mounting system is mostly determined by the three-directional stiffness of each mount block. Because of the manufacturing tolerance and the coupling effect, the stiffness of mounts cannot be maintained stable. The purpose of this study was to find out the way to optimize the stiffness of mounts via the design of experiments (DOE). According to the DOE process, a full factorial design was implemented. The z-direction stiffness of three mount blocks in the mounting system was selected as the three analysis factors. The maximum and the minimum stiffness of each mount block within the manufacturing tolerance were selected as the two levels. The measured vibration of vehicle body under certain loading case was selected as the response factor. After eight times of experiment, the DOE parameters were analyzed with statistical methods.

In the design or match process of vehicle powertrain system, gearbox rattle is a common NVH problem which directly affects passengers’ judgment on the quality and performance of vehicle. During the development process of a passenger car, prototype vehicles have serious gear rattle problem. In order to efficiently and fundamentally control this problem, this work first studied the characteristics and mechanisms of the gearbox rattle. The study results revealed that the torsional vibration of powertrain system was the root cause of gearbox rattle. Then a simulation model of the full vehicle was built with the aid of Simulink® toolbox, which is a graphical extension to MATLAB® for modeling and simulation of variety of systems. With this model, the sensitivity analysis and parametrical optimization were performed, and the simulation results indicated that the dual-mass flywheel (DMF) was the best measure to control the rattle.

The NVH performance is one of the most important concerns in vehicle development. For all-wheel drive (AWD) vehicles and rear-wheel (RWD) drive vehicles, prop shaft is a major transmission component which may cause various NVH problems. This paper focuses on the vehicle NVH problems caused by the second order excitation force of prop shaft. In order to control the NVH performance of the prop shaft efficiently and fundamentally, this work first studied the rotation kinematical characteristics of prop shaft. Then a rigid-elastic coupling model of vehicle driveline was built with the theory of multi-body dynamics. With this model, the sensitive factors that may affect the second order excitation force were investigated. This paper also describes a case study to verify the conclusions which are revealed from the theoretical calculation and the simulation.

An adaptive feed-forward active control system for improving the sound quality of vehicle engine noise is presented in this paper. Based on the narrow-band and periodic properties of engine noise, an artificial waveform, which was synthesized with sinusoidal components at the fundamental frequency of the engine noise and its harmonics, was adopted as the reference signal. Then these primary noise components were canceled via an adaptive notch filter bank, the coefficients of which were updated using the FXLMS algorithm. The core of the designed system is a new algorithm for improving the quality characteristics of the residual noise by adjusting the gain values of the noise component at each reference frequency. The feasibility and advantages of the designed system were validated through both simulation and practical vehicle tests.