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The noise and vibration of electric vacuum pump (EVP) become a major problem for electric vehicles when the vehicle is stationary. This paper aims at the EVP’s abnormal noise of an electric vehicle when stationary. Driver’s right ear (DRE) noise was tested and spectrogram analysis was carried out to identify the noise sources. In order to attenuate this kind of abnormal noise, a new EVP rubber mount with a segmented structure was introduced, which optimized the transfer path of vibration. Then dynamic stiffness and fatigue life of the EVP mount with different rubber hardness were calculated through finite element analysis (FEA) approach. Bench tests of fatigue life and DRE noise were performed to validate the FEA results. Test data of the sample mount shows that sound pressure level of DRE was dramatically attenuated and thus passengers’ ride comfort was enhanced.

With increasing pressure for reduction in CO2 emissions and stricter fuel targets from road vehicles, OEMs around the globe have to electrify their vehicle range to meet increasingly challenging emission standards in recent years and new transmission technologies are gaining more attention in different main markets. The actual and future powertrain development has three major directions in order to reduce or avoid emissions in the transportation sector: Hybrid Vehicles: Hybrid Electric Vehicles (HEV), Plug-in HEV (PHEV) Electric Vehicles (EV); Range Extender Electric Vehicle (REEV); Fuel Cell Electric Vehicles (FCEV), Range Extender FCEV (REFCEV). This paper presents a new type Hybrid transmission which is called “DHT (Dedicated Hybrid Transmission)” technology for cost-effective HEVs and PHEVs; it permits the design of very compact automatic transmissions with an integrated high-voltage electric motor on the output side of the transmission.

In view of the problem of low-frequency (less than 10Hz, such as 0.5Hz, 1.15Hz, 8Hz in this paper) longitudinal vibration exists in a pure electric vehicle, modeling methods of drive-line torsion vibration system are conducted. Firstly, dynamometer test is performed, signals of motor speed and seat rail acceleration are obtained, the frequency characteristics of flutter is determined using the order analysis and time frequency analysis. Then four types of modeling and analysis are investigated facing the drive-line torsion vibration problem, including single model without electromagnetic stiffness, branch model without electromagnetic stiffness, single model considering electromagnetic stiffness and branch model considering electromagnetic stiffness. The results show that, modeling taking into account the electromagnetic stiffness and branches can reflect more low-frequency characteristics helps to reveal the low-frequency longitudinal flutter of the researched electric vehicle.

From traditional vehicle to pure electric vehicle and then to range-extended electric vehicle (ReEV), the electrification of vehicle has caused a great change in NVH characteristics. ReEV has the most complex noise and vibration problems because it behaves both like traditional vehicle and pure electric vehicle. In addition, it has its own specific NVH characteristics. Firstly, internal combustion engine drives the generator rather than drives the vehicle. Due to the structure and load change, auxiliary power unit (APU) performs specific NVH characteristics. In addition, the pure electric mode will have the high frequency noise generated from the driveline because the noise couldn't be masked by the engine. In system level, unexpected and confusing sound in passenger compartment may affect the driver's comfort and judgments. Therefore, more and more attentions on these issues should be paid. NVH study and improvement methods on ReEV are emphasized.

In course of the electrification of vehicle's powertrain, one of the vital problems we've been faced with is the limitation of the vehicle's driving range due to the capacity of currently available batteries. Therefore, range-extended electric vehicle (ReEV) concept has become one of the most promising transitory technologies to compensate this defect. Electric vehicle is supposed to be quiet and comfortable for the customers. However, some annoying sound derived from powertrain and accessories must be reduced or eliminated to meet this requirement. Accessory NVH has an important contribution to ReEV's NVH performance. If it is not well handled, poor vibration and noise may appear. This paper focuses on accessories' NVH performance in ReEV including the NVH problems from steering pump, vacuum pump and AC compressor.

In recent years, electric vehicle and hybrid vehicle are either on the market or under intensive research and development (R&D). Since the concept of auxiliary power unit (APU) was brought into the automotive industry, the range-extended electric vehicle (ReEV) has become the favor of the worldwide manufacturers. Normally, the APU starts and stops more frequently in response to the control strategy compared with traditional vehicles, which will affect the ride comfort of passengers. Thus, APU start-stop NVH refinement is an important aspect of ReEV R&D. In this paper, a subjective evaluation on a ReEV was performed to quickly diagnose NVH issues firstly. Based on subjective results, the NVH experiment in a semi-anechoic room was carried out to troubleshoot these issues. The accelerations of the APU mounts, the seat track and the steering wheel as well as interior noise level were acquired and analyzed.

Tire cavity noise of pure electric vehicles is particularly prominent due to the absence of engine noise, which are usually eliminated by adding Helmholtz resonators with arbitrary transversal section to the wheel rims. This paper provides theoretical basis for accurately predicting and effectively improving acoustic performance of wheel resonators. A hybrid finite element method is developed to extract the transversal wavenumbers and eigenvectors, and the mode-matching scheme is employed to determine the transmission loss of the Helmholtz resonator. Based on the accuracy validation of this method, the matching design of the wheel resonators and the optimization method of tire cavity noise are studied. The identification method of the tire cavity resonance frequency is developed through the acoustic modal test. A scientific transmission loss target curve and fitness function are defined according to the noise characteristics.