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The generator is an important loaded component of an engine front end accessory drive system (EFEADS). With a huge moment of inertia and a highest running speed, the vibration and noise often occurs in operation, which has an effect on the service life. Thus an overrunning alternator decoupler (OAD) is used in the EFEADS for reducing the vibration of system. In this paper, a model of EFEADS with an OAD is established. The impact of the OAD on the dynamic responses of pulley of generator and the system are analyzed, and is verified by bench experiments. And the influence of parameters, such as spring stiffness, moment of inertia of generator and loaded torque on the dynamic performances of the system are studied. The influence of misalignment in pulleys on the dynamic performance of system is also discussed. The presented method is useful for optimizing the dynamic performance of system, such as the oscillation of tensioner arm and the slip ratio of the belt-generator pulley.

A model for a generic layout of an engine front end accessory drive system is established. The dynamic performances of the system are obtained via a numerical method. The dynamic performances consist of the oscillation angle of tensioner arm, the slip ratio of each pulley and the dynamic belt tension. In modeling the system, the hysteretic behavior of an automatic tensioner, the loaded torque of the accessory pulley versus the engine speed, the torsional vibration of crankshaft and the creep of the belt are considered. The dynamic performances of the system at steady state and under accelerating condition are analyzed. An example is provided to validate the established model. The measured results show that the torsional vibration of crankshaft is larger and the dynamic performances of the system are different under accelerating conditions, though the acceleration is small.

During the operation of the ball joint, its service life and transmission efficiency are affected by the internal friction. Taking the ball joint as the research object, based on fractal theory, the friction between the steel ball and the raceway inside the ball joint of an automotive drive shaft system is studied in this paper. During the analysis, the friction between the steel ball and the arc raceway is regarded as the friction between a sphere and an arc raceway surface. In order to describe the friction state more accurately, this paper proposes a correction coefficient to modify the distribution function of contact asperities in the plane, and obtains the distribution function of contact asperities between the sphere and the arc raceway surface. The correction coefficient is related to the load, the size parameters and the material parameters of the steel ball and the raceway.

The ever increasing popularity of electric vehicles and higher requirement on safety and comfort has led heat pump air conditioning system indispensable in electric vehicle. Many studies have shown that the addition of nano particles contributes to great improvement on thermal conductivity than that of conventional refrigerants. Therefore, the application of the magnetic nanorefrigerant in heat pump air conditioning system has massive potential to heighten the heat transfer efficiency. This paper aims at studying the magnetic nanorefrigerant comprised of the magnetic nano powder Fe3O4 and refrigerant R134a. According to the relevant theoretical analyses and empirical formula, the heat transfer coefficient, density, viscosity, and other physical parameters are calculated approximately. In the heat pump air conditioning system of a certain type of electric vehicle, the special working condition parameters are selected to carry out calculation analysis with numerical analysis software.

Because the power unit of electric vehicle has large torque, the rubber mount of electric vehicle is fully compressed under the condition of full throttle acceleration. When designing the mount of electric vehicle, the dynamic-to-static stiffness ratio of mount under the case should be as low as possible to improve the vibration isolation rate of the mount. In this paper, a method for calculating the high frequency dynamic characteristics of rubber isolators under different preloads is presented. Firstly, the dynamic characteristics of rubber specimens under various shear pre-strains were tested. The test results show that the dynamic stiffness of specimen decreases at first and then increases with the increase of shear strain. The viscoelastic parameters of rubber in frequency domain under different pre-strain were identified according to the experimental data. Secondly, a finite element modeling method was proposed.

The decoupling brake-by-wire system controls the key components of the flow path and liquid flow of the whole brake system through the solenoid valve of the bottom control unit. The reference cross-sectional area value at the valve inlet is obtained by calculation, and the valve body structure model is established. The flow channel structure is extracted, and the porous media model is used to replace the fluid area of the filter screen at the entrance of the solenoid valve. The Fluent software is used to analyze the influence on the flow characteristics of the solenoid valve with or without a filter. The accuracy of the model is verified by the experimental results, which also show that the porous medium can effectively and accurately reflect the characteristics of the solenoid valve end filter.

The static characteristics of solenoid valve play an important role in the performance of brake system and can indirectly reflect the response speed of the brake system. The static characteristics of the solenoid valve reflect the electromagnetic characteristics of the solenoid valve itself, revealing the maximum potential of the solenoid valve in the system work, which is one of the important characteristics to characterize the working ability of the solenoid valve. In this paper, a numerical calculation method is used to build a finite element model of the solenoid valve electromagnetic field on the Ansoft Maxwell simulation platform. The model takes into account the nonlinear magnetization characteristics of soft magnetic materials and the air gap.

An Inline 4-cylinder engine is equipped with second-order balance shafts. When the engine is running under no-load acceleration conditions, the gear system of the balance shaft generated whine noise. In this paper, an analysis and experiment method for reducing the whine noise is presented. First, a flexible multi-body dynamic model of the engine is established, which includes shaft and casing deformation, micro-modification of the gears. Taking the measured cylinder pressure as input, the load on each gear of balance shaft gear system is calculated. In addition, the influence of tooth surface micro-modification on the meshed noise was analyzed. The results show that the dynamic meshing force between the crank gear and the shim gear is large under the original tooth surface micro-modification parameters, which is the main reason of the whine noise.

Electronic expansion valve as a throttle element is widely used in heat pump systems and flow characteristics are its most important parameter. The flow characteristics of the electronic expansion valve (EXV) with a valve port diameter of 3mm are studied, when the refrigerant R134a is used as the working fluid. The main factors affecting the flow characteristics are researched by adopting the orthogonal experiment method and single factor control method, for example, inlet pressure, inlet temperature, outlet pressure and valve opening. The results show that the expansion valve opening degree has the greatest influence on mass flow rate. In view of the complicated phase change of the refrigerant passing through electronic expansion valve, it is difficult to model the flow characteristics accurately.

In order to enhance the efficiency of durability testing of automobile parts, a time-frequency domain accelerated editing method of road load time series of rubber mount on powertrain was discussed. Based on Stockwell Transform method and Accumulative Power Spectral Density, a new time-frequency domain accelerated editing method (ST-APSD) was proposed. The accumulative power spectral density was obtained by ST of the load time series signal of automobile powertrain rubber mounting force which is acquired by the real vehicle in the test field. Based on the accumulative power spectral density, the threshold value was proposed to identify and delete the small damage load fragments, and then the acceleration spectrum was obtained.

The dynamic characteristics of hydraulic damping rubber isolators (such as hydraulic bushing and hydraulic mount) are related to excitation amplitude and frequency. Based on the lumped parameter model of hydraulic damping rubber isolator, a unified linear model of complex stiffness is derived and its deficiency is pointed out. Based on the derived linear model, this paper considers the nonlinear damping of inertia channel and the nonlinear stiffness of the upper chamber of the hydraulic damping rubber isolator, so as to establish a new nonlinear model, which can reflect the amplitude and frequency dependence of the dynamic characteristics of the hydraulic damping rubber isolator. Finally, the nonlinear model is used to analyze the dynamic response of hydraulic damping rubber isolator under harmonic excitation and random excitation respectively, and the results are compared with the test results.

The tensioner of the engine front end accessory drive system was taken as a study object, and the mechanical structure and working principle of the automatic tensioner were analyzed. The hysteresis behavior test of tensioner torque-angular displacement was carried out, and the effects of different excitation frequencies and excitation amplitudes on the hysteresis behavior of the tensioner were analyzed. According to the modified Dahl hysteresis model, the model parameters of the tensioner was identified. Based on the identified model parameters, the hysteresis behavior of the tensioner was calculated, and the calculation model accuracy was verified with the tested results. The influence of the hysteresis curve transition area exponent on the tensioner behavior was studied. The dynamic behavior of the engine front end accessory drive system was simulated using the simulation software.

The working principle and performance test method of the gerotor pump with multi-arc combined profile are introduced. According to the formation method of the rotor tooth profile, the calculation method of the inner rotor tooth profile is introduced, and the meshing characteristics of the inner and outer rotors are analyzed. On this basis, a calculation method for the displacement and instantaneous flow rate of the gerotor pump with multi-arc combined profile is proposed. In addition, a calculation model of the flow field characteristics of the gerotor pump with multi-arc combined profile is established, and the validity of the model is verified by experiments. Based on the model of traditional single-arc gerotor pump and the model of the gerotor pump with multi-arc combined profile, the flow rate, internal flow velocity, pressure distribution and gas volume fraction distribution under different working conditions are calculated respectively.

Welding deformation of aluminum alloy is an urgent problem to be solved, it affects the performance and service life of welding products. In this research, in order to compute welding deformation and residual stress, a finite element model of 6061-T6 aluminum alloy was established. The efficiency and the accuracy of the welding residual stress calculation and the welding deformation were significantly improved. By comparing the temperature field and the displacement field of simulation and experiment, the finite element model was validated. Through finite element analysis, Heat input and welding times have important effects on welding deformation and residual stress was found. The welding deformation law and the residual stress distribution law were proposed, after cooling of the welding seams, the plates collapsed to the other side of the heat source along the vertical direction, the welding deformation tendency was heightened by double-sided welding.

Taking a closed airbag suspension system as studying objects, the nonlinear dynamic model of the reservoir, compressor, solenoid valve, pipeline and air spring is established. The compressor exhaust volume, solenoid valve flow rate and air spring charging and discharging rate are calculated and compared with experiment to validate the model. Taking pressure difference and height adjustment rate under different working conditions of an airbag suspension as control measures, a control strategy is developed based on the established nonlinear dynamic model. The result indicates that when the vehicle is in curb weight, design weight and GVW (gross vehicle weight), the working time of the compressor can be reduced by 13.6%, 15.1% and 46.5%, respectively, compared with the conventional mode, during a height adjustment cycle. Then a state observer is proposed to estimate the steady-height for reducing the disturbance of measured height from road excitation.

A rumbling noise is audible in a vehicle passenger compartment during acceleration. Mechanism detail of the rumbling noise is studied. A series of preliminary transfer path experiments investigation on chassis dynamometer shows that the interior rumbling noise is mainly induced by abnormal crankshaft impact at particular crank angle. Spectrum analysis indicates that high level half order harmonic components significantly affects the rumbling noise. Multi-body dynamics model of the powertrain is developed to further investigate the root cause of the abnormal crankshaft impact. Experiment results are used to verify the numeric model. High deviation of main bearing forces at the crank angle 0° to 180° after the Fire Top Dead Center of the no.l cylinder is considered to fundamentally induces the high level half order components. The force ripple coupled with the crankshaft resonance induces the crankshaft rumbling.

The driving pulley is often used as a Torsional Vibration Damper (TVD) for the crankshaft in the front end accessory drive (FEAD) system. Although the crankshaft torsional vibrations are dampened, they are transmitted to the belt transmission and therefore to the driven accessories. The isolation pulley is a new device to reduce the belt tension fluctuation by isolating the belt transmission from the crankshaft torsional vibrations. A five-pulley system with isolation pulley is presented and a non-linear model is established to predict the dynamic response of the pulleys, tensioner motion, tension fluctuation and slippage. The model works in the time domain with Runge-Kutta time-stepping algorithm. The numerical simulation results of harmonic excitations show that the amplitudes of the belt tension fluctuation and the vibrations of each component are reduced significantly. Moreover, the effect of isolation pulley parameters on the system natural frequencies is demonstrated.

The elliptically shaped bearing (ESB) with a rigid, elliptical inner race and a flexible, thin-walled outer race is the most easily damaged core component of harmonic drive. The ESB rotates under cycle load of alternating stress due to its special elliptic structure. Hence, the fault features of ESB such as fatigue spalling and pitting are apt to be concealed by the excitation of impulses caused by alternating between major axis and minor axis. In order to diagnose the fault on raceway surfaces of ESB, a new method of CMWT-FH based on Continuous Morlet Wavelet Transform (CMWT) and FFT-based Hilbert (FH) spectrum analysis is proposed to extract the fault feature.

An automatic tensioner used in an engine front end accessory drive system (EFEADS) is taken as a study example in this paper. The working torque of the tensioner, which consists of the spring torque caused by a torsional spring and the frictional torques caused by the contact pairs, is analyzed by a mathematic analysis method and a finite element method. And the calculation and simulation are validated by a torque measurement versus angular displacement of a tensioner arm. The working torques of the tensioner under a loading and an unloading process are described by a bilinear hysteretic model, and are written as a function with a damping ratio. The rule of the action for the damping devices is investigated based on the simulation and a durability test of the tensioner. A finite element method for the tensioner without damping device is established. Then the radial deformation for the torsional spring under an unconstrained state is obtained.

Electric vehicle motors have the characteristics of fast torque response, large amplitude, and braking feedback torque. Therefore, the excitation of the electric vehicle powertrain has obvious transient impact characteristics, which put forward new requirements for the design of the mounting system. This article carried out the real vehicle test of rapid acceleration and rapid deceleration. A 12-degree-of-freedom nonlinear dynamic model of the electric vehicle mounting system is established. The model is used to calculate the vibration acceleration of the active side and the passive side of the mount, and compared with the test value to verify the correctness of the simulation model. The impact degree, the maximum pitch angle of the powertrain, and the longitudinal acceleration of the powertrain centroid are used as evaluation indicators to analyze the transient response of the electric vehicle mounting system under rapid acceleration and rapid deceleration conditions.