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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.

Design of powertrain mounting bracket is always challenging in achieving good NVH characteristics, sound durability and simultaneously reduced weight. Structural optimization is an effective tool to obtain an optimum design. Depending on the design status, different schemes, i.e. size, topology and shape optimization, are applied. In this paper, a case study of application of structural optimization in the design of a mount bracket has been presented. Firstly, both test and FEA (Finite Element Analysis) results expose problems of the initial design. Therefore, it is necessary to redesign the bracket. With sufficient design freedom and time in topology optimization, design space and optimization parameters are defined. Die direction and other manufacturability considerations for the casting components are vital. Shape optimization is then conducted to further decrease the weight and refine local weakness.

The fully decoupled brake by wire system is a complex system consisting of mechanical components such as springs and rubber and hydraulic structural components coupled together. Compared to conventional braking systems, it is characterized by the full decoupling of the brake pedal from the brake wheel cylinders in normal braking mode, and the pressure fluctuations in the wheel cylinders do not affect the pedal feel. In order to predict brake pedal feel in a passenger car, a dynamic model was developed for both normal and backup braking modes, taking into account the variation of the volume modulus of the brake fluid and the frictional forces of the master cylinder pistons. The influence of different pedal input speeds on the pedal feel characteristic curve was analyzed using static vehicle tests and the related parameters of the braking system were identified in order to correct the design data.

Electromagnetic semi-active hydraulic engine mount (HEM) with double inertia tracks can realize the opening and closing of the inertia tracks through the control of electromagnetic actuator, so as to meet the needs of vibration isolation in different working conditions, but the cost is high. In this paper, without using electromagnetic actuator, a mechanical semi-active HEM with double inertia tracks is designed and manufactured with simple structure and low cost. In this study, the feature of mechanical semi-active HEM with double inertia tracks is that a baffle-current limiting column structure is added in the inertia track. Under different excitation amplitudes, the baffle-current limiting column structure can open and close the inertia track passively. Several mechanical semi-active HEM with double-inertia tracks samples and conventional inertia tracks HEM samples are manufactured and the dynamic characteristics of these samples under low frequency excitation are tested.

The application of turbochargers in fuel vehicles brings high-frequency noise, which seriously affects the vehicle's ride comfort. The hiss noise of a turbocharged car is improved in this paper. Firstly, under different operating conditions and whether the air intake system is wrapped, the noise in the vehicle cabin and the driver's right ear is tested, and the noise sources and noise characteristics are identified. Then, the acoustic calculation model of the muffler is established, and the transmission loss (TL) of the original muffler behind the turbocharger (MBT) is calculated. The TL of the muffler is measured by the double-load impedance tube method. The finite element calculation model is verified by comparing the TL of muffler calculated with tested. Thirdly, the MBT is redesigned. The improved muffler significantly improves the performance of eliminating high-frequency noise, and its TL beyond 20 dB is expanded to the band of 1600 ~ 3500 Hz.

In the existing literature concerning the calculation of the output speed of the silicone oil fan clutch and the silicone oil temperature, the theoretical calculation method is all adopted to establish the calculation formulas of moment transmission and silicone oil shear viscous heat by extracting the structural parameters of the clutch model, in order to solve the output speed and silicone oil temperature of the clutch under stable working state. At present, CFD (Computational Fluid Dynamics) numerical simulation method has not been used to solve the problem. In this paper, the CFD simulation method is used for the first time. Considering the change of silicone oil viscosity with temperature, a double-sided slot silicone oil fan clutch was taken as the research object to established the CFD simulation model of hydro-viscous drive to solve the clutch output speed and silicone oil temperature.

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.

This paper designs the important components and structure of the integrated electro-hydraulic brake system (I-EHB). Firstly, the simplified linear system is modeled, and the transfer function without considering the nonlinear disturbance such as system friction is derived, and the correctness of the linear system is preliminarily verified by AMESim. Then set up the I-EHB system test bench, and use the Stribeck friction model to identify the friction torque parameters in the static and kinetic friction stages of the system to obtain a more accurate friction model. Finally, based on the I-EHB system model of friction disturbance, a pressure-speed-current three-loop cascade PID controller is designed, and a feedforward controller based on the system model is added to form the control structure of “pressure feedforward compensation + pressure-speed-current closed-loop cascade PID”.

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.

The vehicle will produce certain shock and vibration during the braking process, which will affect the driving experience of the driver. Aiming at the problems of pitch vibration, longitudinal vibration and shock during the braking process, this paper proposes a planning and following control method for target longitudinal acceleration in post-braking phase, and designs control trigger strategies. Target longitudinal acceleration planning takes minimizing longitudinal shock as the design goal. The following control takes the brake pressure as the control object, and adopts the “feedforward +PID feedback” method to follow the target longitudinal acceleration. Besides, considering the safety of braking process, the trigger condition of control is designed which utilizes BP neural network method to judge whether the control has to be triggered. Based on Simulink software, the simulation model of straight-line braking is established.

Turbulence caused by the blade tip of engine cooling fan is one of important noise generating factors. Existing theoretical researches show that the bionic serrated designs applied at the front and rear edges of fan blades can effectively improve the airflow characteristics and reduce the aerodynamic noise. However, the effect of its application at the blade tip needs to be explored and verified. In this research, vehicle engine fans whose tips are designed and remodeled with different size of triangular serrated edge have been tested on airduct, to explore the fan static pressure and noise that caused by changing of period and amplitude size. The large eddy simulation (LES) and FW-H acoustic analogy method are adopted to calculate the transient noise of each designed fan.

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.

Uniaxial fatigue tests of rubber dumbbell specimens under different mean and amplitude of strain are carried out. An Extreme Learning Machine (ELM) model optimized by Dragonfly Algorithm (DA) is proposed to predict the fatigue life of rubber based on measured rubber fatigue life data. Mean and amplitude of strain and measured rubber fatigue life are taken as input variables and output variables respectively in DA-ELM model. For comparison, genetic algorithm (GA) and particle swarm optimization (PSO) are used to optimize ELM parameters, and GA-ELM and PSO-ELM models are established. The comparison results show that DA-ELM model performs better in predicting the fatigue life of rubber with least dispersion. The coefficients of determination for the training set and test set are 99.47% and 99.12%, respectively. In addition, a life prediction model equivalent strain amplitude as damage parameter is introduced to further highlight the superiority of DA-ELM model.

If a car is braked frequently or at high speed, the thermal decay of brake system performance appears, which reduces the braking performance of the car. To compensate brake moment reduction during braking at thermal decay of brake system, a compensation strategy of brake moment is designed by using “feedforward +PID feedback” to pressure at wheel braking cylinder. The trigger and exit conditions of the strategy for the wheel cylinder pressure are proposed based on the threshold. A vehicle model consisting braking system is established if a vehicle runs at straight line, and the braking distance and braking acceleration are estimated, the results shown that the thermal decay compensation control strategy proposed in this paper can reduce the braking distance and braking time.

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.

A new single-attachment air spring system with a parallel one-way tube is designed as a vibration isolation device for vehicles. The dynamics model of the new two-throttle tube air spring is established first, and the accuracy of the two-tube model is verified experimentally. Finally, the experimental results of the two-throttle tube air spring and the single-tube air spring are compared to analyze the effects of the tube diameter, tube length and additional air chamber volume on the dynamic stiffness of the two-throttle tube air spring. The results show that the combination of throttle tubes of different diameters has a great influence on the stiffness and damping characteristics of the air spring.

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.

A fourth-order mathematical model for I-EHB (integrated electro-hydraulic brake) system was derived from its mechanical and hydraulic subsystems. The model was linearized at equilibrium state and then was verified by AMESIM software. The friction model of the system was analyzed based on static friction and viscous friction. A bench test was designed to identify the parameters of friction model. As the I-EHB system worked at different braking conditions, a PID-based switching controller was designed to track the target servo cylinder pressure. Both simulations and experiments results showed that, the response time of pressure was less than 120ms, and there was no overshoot, which helped handling different braking conditions and improving the braking safety and comfort.

There is the possibility of decoupler’s impact noise in hydraulic engine mount (HEM) with a free decoupler, but there is little research on this aspect. As for how to solve the problem of decoupler’s impact noise, most of the papers are only improved through trial and error. This article uses three HEMs with different decoupler plates and cages as the research object for the experiment. First, calculate the contact force between the decoupler plate and cage of the HEM through the finite element method, to determine whether the decoupler’s impact noise problem will occur. Then design the bench test of the abnormal noise of the HEMs to verify the conclusion obtained by the calculation of the contact force. Next, deduce the relationship between the transmitted force at the chassis side of the HEM and the impact force of the decoupler, and propose a test method for evaluating the decoupler’s impact noise based on the transmitted force at the chassis side of the HEM.