International Journal of Automotive Technology最新文献

Rubber mixing plays a very important role in the tire manufacturing process, and the rubber mixing effect affects the quality of the finished tire. Numerical simulation methods are often used to investigate the optimal rubber mixing parameters. To solve the problem of rubber mixing numerical simulation calculations in non-isothermal partial filling conditions when the calculation is difficult, this paper is based on the principle of decoupling to design an algorithm to calculate the rubber temperature in the rubber mixing process. The rubber viscosity and shear rate are processed using the Bird–Carreau model, and the rubber temperature and viscosity are decoupled using the Arrhenius-Law model. Define the heat generation rate of rubber based on the rubber viscosity and shear rate obtained from transient numerical simulation, and obtain the temperature value of each rubber unit. Numerical simulation calculations of rubber compounding under non-isothermal partial filling conditions are realized. To verify the feasibility of the algorithm, the designed algorithm is applied to study the effect of rubber mixing machine speed on the rubber mixing effect. Finally, comparing the numerical simulation results with the experimental results, the effectiveness of this algorithm is proven.

This study aimed to determine a method to suppress thermal runaway in electric vehicles by passing water directly inside the battery case. A scaled-down model experiment was conducted using a lithium-ion battery pack consisting of six 18650 cells, which is equal to about one-thousandth of an electric vehicle’s charging capacity. The heat generation rate, heat transfer coefficient, and time constant for cooling were measured using a simple model for the cooling methods, thermal runaway stages, and state of charge. When thermal runaway occurred during natural cooling, the battery temperature rose to 630 °C at a rate of 116 °C/s. Through water injection, the thermal runaway was quickly suppressed with a time constant of about 3 s and a heat transfer coefficient of 3400 W/m²·K. The water effectively prevented chain explosions and kept harmful gases emitted from the batteries. It was found that it is difficult to completely suppress thermal runaway using the latent heat of the stagnant water in the spaces between cylindrical batteries. If the experimental results of this study were to be applied to an actual vehicle, it is expected that thermal runaway could be suppressed with a time constant of about 170 s and 1 ton of water.

To cover the problem of dangerous state prediction ahead of vehicle rollover and rescue the vehicle under abrupt cornering condition, a dynamic Bayesian network (DBN) merged robust control is developed to balance the vehicle ride comfort and handling performance. To discretize the automobile state attributes and prepare for the prediction, class attribute contingency coefficient (CACC) is adopted to pre-process the data conveniently and establish the category labels. The key contributions of this paper are efficient rollover prediction with probabilistic and numerical representation, a mapping rule from rollover probabilities to T–S fuzzy membership values, and an intelligent objective switchable control between ride comfort and roll stability. The co-simulation method is adopted to verify the effectiveness of this method with passive suspension, semi-active suspension, and optimal control active suspension. It is shown that the DBN-based robust control is able to reduce the roll angle by more than 27% compared to the passive suspension under double-lane change condition and has the best balancing performance. From the perspective of ride comfort testing on bounce sinusoidal roads, the vehicle DBN incorporating robust controllers can effectively reject vibrations and switch control objectives based on its running conditions.

Abstract

The objective of this study was to analyze through spray and engine experiments the effects of replacing mechanical injectors. The spray characteristics of the mechanical injectors of a used diesel engine and those of new mechanical injectors of the same model were compared. The injection quantity of the new injector was approximately 2–4% higher than that of the used injector owing to the deposit on the nozzle surface. The opening pressure of the used injector was 225 bar on account of the deterioration of the spring inside the injector. This pressure was lower than that of the new injector. The average spray penetration length of both injectors increased similarly up to 2 ms after injection. Owing to deposits on the nozzle surface, the spray angle of the used injectors tended to be smaller than those of the new injectors. The results of engine experiments showed that the new injectors recovered over 90% of engine torque and engine power on account of the increased fuel injection quantity. However, employing the new injectors caused heat loss and fuel consumption rate deterioration. The new injectors effectively reduced NOx and PM emissions by retarding the fuel injection timing and increasing the fuel injection pressure.

Lightweight electric vehicles (LEVs) possess great advantages in the viewpoint of fuel consumption, environment protection, and traffic mobility. However, due to the drastic reduction of vehicle weights and body size, the effects of inertial parameter variation in LEV control system become much more pronounced and have to be systematically estimated. This paper presents a dual adaptive unscented Kalman filter (AUKF) where two Kalman filters run in parallel to synchronously estimate vehicle inertial parameters and additional dynamic states such as vehicle mass, vehicle yaw moment of inertia, the distance from front axle to centre of gravity and vehicle sideslip angle. The proposed estimation only integrates and utilizes real-time measurements of in-wheel-motor information and other standard in-vehicle sensors in LEV. The LEV dynamics estimation model including vehicle payload parameter analysis, Pacejka model, wheel and motor dynamics model is developed, the observability of the observer is analysed and derived via Lie derivative and differential geometry theory. To address nonlinearities and undesirable noise oscillation in estimation system, the dual noise adaptive unscented Kalman filter (DNAUKF) and dual unscented Kalman filter (DUKF)are also investigated and compared. Simulation with various manoeuvres are carried out to verify the effectiveness of the proposed method using MATLAB/Simulink-Carsim^®. The simulation results show that the proposed DNAUKF method can effectively estimate vehicle inertial parameters and dynamic states despite the existence of payload variations.

An optimal shift control strategy for electric vehicles with the two-speed dual-clutch transmission is proposed to reduce the vehicle jerk and friction work during gear shift. The dynamic model of the powertrain considering the stick–slip friction of clutch is built. The developed control scheme is divided into two stages. For the upper level control, a finite-time linear quadratic regulator (LQR) is designed to optimize the target trajectories of torque and speed of motor and clutch by integrating both jerk and friction work in the cost function. Considering that the clutch torque is necessary for calculating the target trajectories but cannot be measured directly, the Kalman filter is employed to estimate the clutch torque. For the lower level control, a combination of torque feedforward and speed feedback controller is constructed to control the motor torque and clutch pressure. To validate the effectiveness of the proposed strategy, comparisons with the strategies based on the polynomial method and unsmooth LQR are carried out. Simulation results and hardware-in-loop test reveal that the jerk and friction work are both reduced, indicating better shift performance.

Homogeneous charge-induced ignition (HCII), which uses trace diesel to induce the ignition of gasoline pre-mixture, is characterized by rapid lean combustion and is generally regarded as efficient, clean and controllable. In this paper, a conventional diesel engine has been modified to run all cylinders in HCII mode and the influence of diesel injection pressure (DIP) on overall engine performance was experimentally studied. Results show that the increase of DIP can expand the ignition area of gasoline and enlarge the premixed combustion ratio of diesel, thus promoting rapid combustion and improving brake thermal efficiency. The increase of DIP is beneficial to the control of ignition time and combustion phase, thus reducing the cyclic fluctuation. The increase of DIP can effectively reduce the emission of total hydrocarbon, carbon monoxide and smoke, while the emission of nitrogen oxides (NOx) is insensitive to the change of DIP, so the trade-off relationship between NOx and smoke disappears. However, excessive DIP will still lead to increased combustion noise, and deteriorated combustion quality caused by too less inducing diesel, etc. The appropriate value is about 1000 bar within the test range.

In this paper, we present a data-driven modeling method for lateral motion control of unknown vehicle models. Vehicle’s motion can be modeled linearly but this model has complex and nonlinear characteristic. Therefore, it is necessary to know the exact information of the car chassis and requires a knowledge and understanding of dynamics. To solve these drawbacks, we linearly represent full vehicle's lateral dynamics which include nonlinear behavior using dynamic mode decomposition (DMD), one of the data driven modeling methods. To determine the validity of the model obtained using the DMD method, we conducted a simulation of the comparison of the output states between the existing model and the model obtained through DMD modeling, using the scenario of a dynamic maneuver called a double line change during lateral motion of a vehicle. After determination of validation is completed, we designed a lane keeping system by applying a model predictive control to specifically evaluate the model of the proposed method. Performance was derived by comparing the error caused by the vehicle driving on the course with the controller of the simulation. The performance of the proposed approach has been evaluated through simulations and is useful when the model is inaccurate.

This research proposes a parameter scaling method for dimensional analysis in extreme maneuver scenarios. Scaled vehicle experiments using dimensional analysis offer advantages in terms of test location, driver safety, and cost savings. Previous studies have overlooked the nonlinear effects of tires in dimensional analysis. Two methods are presented: scaling the frictional coefficient between tires and surfaces and virtual scaling of gravitational acceleration through time scaling. The methods were validated using a 1/8 scaled vehicle and the CarSim software program. This research establishes a practical and valid approach to parameter scaling in vehicle dynamics, considering tire nonlinearity and accommodating extreme maneuvers.

To solve the complicated steering control of small vehicles in the agriculture and difficult steering on complex roads, this study designed a wheel-track composite vehicle. The vehicle incorporated a novel power differential steering mechanism with dual driving, enabling steering through the differential rotation of the rear two wheels. The vehicle is simple to control, small in size, and is able to work under the conditions of complex roads, such as hills, mountains, and muddy land. The study initially focused on presenting the design, theoretical analysis, and dynamic simulation analysis of the power differential steering mechanism with dual driving. Subsequently, the vehicle underwent modeling and simulation using UG software to validate the reasonability of the values. Finally, utilizing test data, four mathematical models for the actual steering radius of the vehicle on four road surfaces were derived through neural network fitting. The maximum relative error between the model results and the actual steering radius value was reported to be 3.53%. The advantages of the vehicle included continuous radius steering, deceleration and torsion increase, differential lock, etc. This made it well-suited for applications in all-terrain military and civilian vehicles, as well as various special equipment mobile platforms equipped with walking devices.