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The adhesion control is the basic technology of active safety for the four-wheel driven EV. In this paper, a novel adhesion control method based on fuzzy logic control is proposed. The control system can maximize the adhesion force without road condition information and vehicle speed signal. Also, the regulation torque to prevent wheel slip is smooth and the vehicle driving comfort is greatly improved. For implementation, only the rotating speed of the driving wheel and the motor driving torque signals are needed, while the derived information of the wheel acceleration and the skid status are used. The simulation and road test results have shown that the adhesion control method is effective for preventing slip and lock on the slippery road condition.

During a car launch, the driving torque from driveline acts on brake disk, and may lead the pad to slip against the disk. Especially with slow brake pedal release, there is still brake torque applies on the disk, which will retard the rotation of disk, and under certain conditions, the disk and pad may stick again, so the reciprocated stick and slip can induce the noise and vibration, which can be transmitted to a passenger by both tactile and aural paths, this phenomenon is defined as brake groan. In this paper, we propose a nonlinear dynamics model of brake for bidirectional, and with 7 Degrees of Freedom (DOFs), and phase locus and Lyapunov Second Method are utilized to study the mechanism of groan. Time-frequency analysis method then is adopted to analyze the simulation results, meanwhile a test car is operated under corresponding conditions, and the test signals are sampled and then processed to acquire the features.

Fatigue behavior of aluminum alloys under multiaxial loading was investigated with both cast aluminum A356-T6 and wrought alloy 6063-T6. The dominant multiaxial fatigue crack preferentially nucleates from flaws like porosity and oxide films located near the free surface of the material. In the absence of the flaws, the cracking/debonding of the second phase particles dominates the crack initiation and propagation. The number of cracked/debonded particles increases with the number of cycles, but the damage rate depends on loading paths. Among various loading paths studied, the circle loading path shows the shortest fatigue life due to the development of complex dislocation substructures and severe stress concentration near grain/cell boundaries and second phase particles.

Based on the working model of a diesel engine, the influence of 2 Miller cycle strategies-Early Intake Valve Closure (EIVC) and Late Intake Valve Closure (LIVC) on the combustion and emissions of diesel engine was analyzed. Then the working condition of each Miller cycle strategies on the engine under the rated speed was optimized through the adjust of the valve timing, boost pressure and the injection timing. The research found that both delaying and advancing the closure timing of the intake valve can decrease the pressure and temperature during compression stroke, prolonging the ignition delay. However, due to the decrease of the working media inside the cylinder, the average in-cylinder temperature and soot emissions will increase, which can be alleviated by raising the boost pressure and the resulting compensation of the intake loss.

Recently, electro-hydraulic brake systems (EHB) has been developed to take place of the vacuum booster, having the advantage of faster pressure build-up and continuous pressure regulation. In contrast to the vacuum booster, the pressure estimation for EHB is worth to be studied due to its abundant resource (i.e. electric motor) and cost-effective benefit. This work improves an interconnected pressure estimation algorithm (IPEA) based on actuator characteristics by introducing the vehicle dynamics and validates it via vehicle tests. Considering the previous IPEA as the prior pressure estimation, the wheel speed feedback is used for modification via a proportional-integral (PI) observer. Superior to the IPEA based on actuator characteristics, the proposed PEA improves the accuracy by more than 20% under the mismatch of pressure-position relation.

In this paper, characteristics of gas emission and particle size distribution are investigated in a common rail diesel engine fueled with biodiesel blends. Gas emission and particle size distribution are measured by AVL FTIR - SESAM and SMPS respectively. The results show that although biodiesel blends would result in higher NOx emissions, characteristics of NOx emissions were also dependent on the engine load for waste cooking oil methyl ester. Higher blend concentration results in higher NO2 emission after two diesel oxidation catalyst s (DOC). A higher blend concentration leads to lower CO and SO2 emissions. No significant difference of Alkene emission is found among biodiesel blends. The particle size distributions of diesel exhaust aerosol consist of a nucleation mode (NM) with a peak below 50N• m and an accumulation mode with a peak above 50N • m. B100 will result in lower particulates with the absence of NM.

The active components, such as OH and their concentrations in the coflow, have a strong effect on the combustion process of diesel fuel spray flames in the Controllable Active Thermo-Atmosphere (CATA), which then will affect the soot incandescence of the spray flames. CO2 and H2O2, the additives which have contrary effect on the concentration of the active components, were mixed separately into the thermo-atmosphere before the jet spray were issued into the coflow, which changed the boundary condition around the central jet and influenced the combustion characteristics and soot incandescence. The combustion characteristics such as ignition delay and flame liftoff height of the central spray flames are measured and the linkage between these two parameters is investigated at different coflow temperatures.

This paper describes a methodology to estimate yaw rate of a 4-wheel-drive electric vehicle, in which wheel driven torque can be independently controlled by electric motor. Without non-driven wheels it would be difficult to estimate the vehicle yaw rate precisely, especially when some of the four wheels have large slip ratio. Therefore, a model based estimation methodology is put forward, which uses four wheel speeds, steering wheel angle and vehicle lateral acceleration as input signals. Firstly the yaw rate is estimated through three different ways considering both vehicle kinematics and vehicle dynamics. Vehicle kinematics based method has good estimation accuracy even when the vehicle has large lateral acceleration. However, it can not provide satisfying results when the wheel has large slip ratio. In contrast, vehicle dynamics based method is not so sensitive to wheel slip ratio.

A biodiesel fuel, obtained from Jatropha seed in China, was tested in a direct injection, high pressure common-rail diesel engine for passenger cars. Effects of biodiesel on particle number and size distribution of the diesel engine are studied using an Engine Exhaust Particle Sizer (EEPS). Base petroleum diesel fuel, 10% and 20% v/v biodiesel blends with the base petroleum diesel fuel, the biodiesel fuel (B0, B10, B20 and B100 fuels) were tested without engine modification. For all test fuels, the particle number and size distribution show unimodal or bimodal log-normal distribution, with a nucleation mode peak value in 6.04nm to 10.8nm particle diameter, and with an accumulation mode peak value in 39.2nm to 60.4nm particle diameter.

Path following controller of a six-wheel skid-steering vehicle is designed. The vehicle speed is controlled through engine speed control and the lateral vehicle steering is controlled through hydraulic braking on each side. Contrary to the common approaches considering non-holonomic constraints, vehicle dynamic characteristics and nonlinear characteristics of tire are considered. A hierarchical control structure is applied in this vehicle control system. The kinematic controller works out the reference yaw rate and reference vehicle speed. And a robust dynamic controller tracks the reference signal. In addition, the dynamic controller takes actuator ability into account.

For an innovative opposed-piston diesel engine (OPE) with two-stroke operation mode, it attracted even more attentions than ever in some developed countries all around the world, attributed to the unique advantages of higher power density that conducive to downsize IC engine, as well as the potential of further reducing fuel consumption for outstanding thermal efficiency. To achieve fast practical application and ensure the feasibility in concept design stage, the performance characteristic of OPE crankshaft system was investigated, and thus a theoretical analytic model of crankshaft system in an OP2S (Opposed-piston two stroke) engine was established. The effects of all structural design variables on averaged output torque of OPE crankshaft were analyzed, respectively. It was found that the initial crank angle difference between inner crank web and outer crank web was considered as a most critical contributor to boost the averaged torque output than other design variables.

Boosting and downsizing is the trend of future gasoline engine technology. For the turbocharged engines, the actuation of intake boosting pressure is very important to the performance output. In this paper, a GT-Power simulation model is built based on a 1.5 L turbocharged gasoline engine as the research object. The accuracy of model has been verified through the bench test data. Then it is conducted with numerical simulation to analyze the effect of wastegate diameter on the engine performance, including power output and fuel economy. Mainly the wastegate diameter is optimized under full engine operating conditions. Finally an optimal MAP of wastegate diameter is drawn out through interpolation method. By the transmission relationship between wastegate and actuator, a wastegate control MAP for electric actuated wastegate can be obtained.

As one of the most crucial components in electric vehicles, power batteries generate abundant heat during charging and discharging processes. Thermal management system (TMS), which is designed to keep the battery cells within an optimum temperature range and to maintain an even temperature distribution from cell to cell, is vital for the high efficiency, long calendar life and reliable safety of these power batteries. With the desirable features of low system complexity, light weight, high energy efficiency and good battery thermal uniformity, thermal management using composite phase change materials (PCMs) has drawn great attention in the past fifteen years. In the hope of supplying helpful guidelines for the design of the PCM-based TMSs, this work begins with the summarization of the most commonly applied heat transfer enhancement methods (i.e., the use of thermally conductive particles, metal fin, expanded graphite matrix and metal foam) for PCMs by different researchers.

In this paper, a novel method is proposed to establish the vehicle yaw stability criterion based on the sideslip angle-yaw rate (β-r) phase plane method. First, nonlinear two degrees of freedom vehicle analysis model is established by adopting the Magic Formula of nonlinear tire model. Then, according to the model in the Matlab/Simulink environment, the β-r phase plane is gained. Emphatically, the effects of different driving conditions (front wheels steering angle, road adhesion coefficient and speed) on the stability boundaries of the phase plane are analyzed. Through a large number of simulation analysis, results show that there are two types of phase plane: curve stability region and diamond stability region, and the judgment method of the vehicle stability domain type under different driving conditions is solved.

Path tracking is the rudimentary capability and primary task for autonomous ground vehicles (AGVs). In this paper, a novel four-wheel-independent-steering (4WIS) and four-wheel-independent-drive (4WID) electric vehicle (EV) is proposed which is equipped with steer-by-wire (SBW) system. For path-tracking controller design, the nonlinear vehicle model with 2 degrees of freedom (DOF) is built utilizing the nonlinear Dugoff tire model. The nonlinear dynamic model of SBW system is conducted as well considering the external disturbances. As to the path-tracking controller design, an integrated four-wheel steering (4WS) and direct yaw-moment control (DYC) system is designed based on the model predictive control (MPC) algorithm to track the target path described by desired yaw angle and lateral displacement. Then, the fast terminal sliding mode controller (FTSMC) is proposed for the SBW system to suppress disturbances.

Recent toxicological and epidemiologic studies have shown that diesel emissions have been a significant toxic air contaminant. Catalyzed DPF (CDPF) not only significantly reduces the PM mass emissions (>90%), but also further promotes carrier self-regeneration and oxidize more harmful gaseous pollutants by the catalyst coated on the carrier. However, some ultrafine particles and potentially harmful gaseous pollutants, such as VOCs species, originally emitted in the vapor-phase at high plume temperature, may penetrate through the CDPF filter. Furthermore, the components and content of catalyst coated on the CDPF could influence the physicochemical properties and toxicity intensity of those escaping ultrafine particles and gaseous pollutants. In this work, (1) we investigated the influence of precious metal content as a variable parameter on the physicochemical properties and catalytic activities of the small CDPF samples.

Manufacturers have been encouraged to accommodate advanced downsizing technologies such as the Variable Displacement Engine (VDE) to satisfy commercial demands of comfort and stringent fuel economy. Particularly, Active control engine mounts (ACMs) notably contribute to ensuring superior effectiveness in vibration attenuation. This paper incorporates a PID controller into the active control engine mount system to attenuate the transmitted force to the body. Furthermore, integrated time absolute error (ITAE) of the transmitted force is introduced to serve as the control goal for searching better PID parameters. Then the particle swarm optimization (PSO) algorithm is adopted for the first time to optimize the PID parameters in the ACM system. Simulation results are presented for searching optimal PID parameters. In the end, experimental validation is conducted to verify the optimized PID controller.

Biodiesel as a renewable energy is becoming increasingly attractive due to the growing scarcity of conventional fossil fuels. Meanwhile, the development of after-treatment technologies for the diesel engine brings new insight concerning emissions especially the particulate matter pollutants. In order to study the coupling effects of biodiesel blend and CCRT (Catalyzed Continuously Regeneration Trap) on the particulate matter emissions, the particulate matter emissions from an urban bus with and without CCRT burning BD0 and BD10 respectively was tested and analyzed using electrical low pressure impactor (ELPI). The operation conditions included steady state conditions and transient conditions. Results showed that the particulate number-size distribution of BD10 and BD0 both had two peaks in nuclei mode and accumulation mode at the conditions of idle, low speed and medium speed while at high speed condition the particulate number-size distribution only had one peak.

Recently Hybrid Electric Buses (HEBs) have been widely used in China for energy saving and emission reduction. In order to study the real road emission performance of HEBs, the emission tests of an in-use diesel-electric hybrid bus (DHEB) are evaluated both on chassis dynamometer over China City Bus Cycles (CCBC) and on-road using Portable Emissions Measurement Systems (PEMS). The DHEB is powered by electric motor alone at speed of 0~20km/h. When the speed exceeds 20km/h, engine gets engaged rapidly and then works corporately with the electric motor to drive the bus. For chassis dynamometer test over CCBC, emissions of NOx, particulate number, particulate mass, and THC of the DHEB are 7.68g/km, 5.88E+11#/km, 0.412mg/km, and 0.062g/km, respectively. They have all decreased greatly compared to those of the diesel bus. But the CO emission which is 3.48g/km has increased significantly. Then the Real Driving Emissions (RDE) of the DHEB are compared with the dynamometer test results.

An EURO 3 certified common rail diesel engine was fueled with pure petroleum diesel (EURO 4 standard) and three different alternative blended diesel fuels, 10% biodiesel blended diesel (B10), 10% gas to liquid blended diesel (G10) and 10% water emulsified diesel (E10). Tests were performed at different engine speeds and load states. Particle number concentration and size distribution data were obtained from an engine exhaust particle sizer (EEPS). Over all the working conditions, total particle and nucleation mode particle number concentration among these fuels from high to low were in this order: B10, E10, pure diesel and G10. Proportions for nucleation mode particle over all the operating states in that order were 89%, 82%, 59% and 66%. Particle size distributions of B10 and E10 presented bimodal logarithmic distributions with outstanding nucleation mode peaks at all working conditions.