Search Results

The design of engine intake system affects the intake uniformity of each cylinder of the engine, which in turn has an important impact on the engine performance, the uniform distribution of EGR exhaust gas and the combustion process of each cylinder. In this paper, the constant-pressure supercharged diesel engine intake pipe is used as the research model to study the intake air flow unevenness of the intake pipe of the supercharged diesel engine. The pressure boundary condition at the outlet of each intake manifold is set as the dynamic pressure change condition. The three-dimensional numerical simulation of the transient flow process in the intake manifold of diesel engine is simulated and analyzed by using numerical method, and the change of the Intake air flow field in the intake manifold under different working conditions during the intake overlapping period is discussed.

This paper presents a novel lumped parameter model(LPM) and its parameter identification method for the hydraulic engine mount(HEM) with a suspended decoupler. In the new model the decoupler membrane’s variable stiffness caused by being contact with the metallic cage is considered. Therefore, the decoupler membrane in the model can be taken as a spring. As a result, two parameters of the decoupler’s variable stiffness and the equivalent piston area are added. Then the finite element method is employed to analyze the suspended decoupler membrane’s variable stiffness characteristics under the contact state with the metallic cage. A piecewise polynomial is used to fit the decoupler membrane’s variable stiffness. To guarantee the symmetry of the stiffness, the polynomial only keeps the odd power coefficients.

Positioning system is a key module of autonomous driving. As for LiDAR SLAM system, it faces great challenges in scenarios where there are repetitive and sparse features. Without loop closure or measurements from other sensors, odometry match errors or accumulated errors cannot be corrected. This paper proposes a construction method of LiDAR anchor constraints to improve the robustness of the SLAM system in the above challenging environment. We propose a robust anchor extraction method that adaptively extracts suitable cylindrical anchors in the environment, such as tree trunks, light poles, etc. Skewed tree trunks are detected by feature differences between laser lines. Boundary points on cylinders are removed to avoid misleading. After the appropriate anchors are detected, a factor graph-based anchor constraint construction method is designed. Where direct scans are made to anchor, direct constraints are constructed.

The effectiveness of after-treatment systems depends on the exhaust gas temperature, which is low during cold-start. As a result, Euro III, Euro IV and FTP75 require that the emissions tests include exhaust from the beginning of cold start. It is proved that 50%∼80% of HC and CO emissions are emitted during the cold start and the amount of unburned fuel from the crevices during starting is much higher than that under warmed engine conditions. The piston crevices is the most part of combustion chamber crevices, and results of mathematical simulations show that the piston crevice contribution to HC emissions is expected to increase during cold engine operation. Based on the transient HC test data and the double zone combustion model, this paper presents the study of the crevice HC Mechanism of the first firing cycle at cold start on an LPG SI Engine. A fast-response flame ionization detector (FFID) was employed to measure transient HC emissions of the first firing cycle.

As a prerequisite for energy management of hybrid vehicles, the results of speed prediction can optimize the performance of vehicles and improve fuel efficiency. Energy management strategies are usually developed based on standard driving cycles, which are too generalized to show the variability of driving conditions in different time and locations. Therefore, this paper constructs a representative driving cycle based on driving data of the corresponding time and location, used as historical information for prediction. We propose a method to construct the driving cycle based on Markov chain theory before constructing the prediction model. In this paper, multiple prediction methods are compared with traditional parametric methods. The difference in prediction accuracy between multiple prediction methods under the single time scale and multiple time scale were compared, which further verified the advantages of the speed prediction method based on Markov chain theory.

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.

The turbocharger air intake noise during transient conditions like wide open throttle and tip-in/out affects the passenger ride comfort. This paper aims to study an optimized design of multi-chamber perforated resonators to attenuate this noise. The noise produced by a turbocharger in a test vehicle has been measured to find out the noise spectral characteristics which can be used to design the acoustic targets including the amplitude and frequency range of transmission loss (TL). The structural parameters of the resonators are optimized based on genetic algorithm (GA) and two-dimensional prediction theory of the resonator TL. The optimized resonators are installed on the test vehicle to verify the actual noise reduction effect. The results suggest that the broadband noise has been eliminated, and subjective feelings are greatly improved.

With the increasing application of turbochargers on internal combustion engines, there are more and more examples of vibration faults in turbochargers. The dynamics characteristics of the bearing-rotor system of engine turbocharger systems have received extensive attention. The bearing-rotor system dynamics is a discipline that couples bearing fluid lubrication research and rotor dynamics. The lubrication characteristics of the bearing and the dynamic characteristics of the rotor must be studied at the same time. In this paper, the lubrication model of floating ring bearing of turbocharger is established, and the viscosity lubrication condition considering heat transfer effect is obtained. Based on the Capone cylindrical bearing oil film force model, the nonlinear oil film force equation of the floating ring bearing is deduced. Further the dynamic model of the Jeffcott rotor-floating ring bearing system is established.

The fuel-saving potential of a series hybrid electric vehicle (SHEV) was investigated in this work based on the future goals and technical roadmaps proposed by China's automobile and internal combustion engine (ICE) industry. The genetic algorithm optimization method and dynamic programming energy management strategy are used to optimize the key component parameters of a typical SHEV SUV to improve the fuel economy of the vehicle. Results showed that the fuel consumption of the vehicle would be 3.24 L / 100km in 2035, which is 37.21% less than 5.16 L / 100km in 2020, following the industries’ roadmaps. The results also indicated that the improvement of the ICE’s thermal efficiency is the main reason for the decrease of the vehicle’s fuel consumption. In addition, the improvement of working points and the reduction of energy losses of the key components also contribute to the improvement of the fuel economy.

Two control strategies, safety preferred control and master cylinder oscillation control, were designed for anti-lock braking on a novel integrated-electro-hydraulic braking system (I-EHB) which has only four solenoid valves in its innovative hydraulic control unit (HCU) instead of eight in a traditional one. The main idea of safety preferred control is to reduce the hydraulic pressure provided by the motor in the master cylinder whenever a wheel tends to be locking even if some of the other wheels may need more braking torque. In contrast, regarding master cylinder oscillation control, a sinusoidal signal is given to the motor making the hydraulic pressure in the master cylinder oscillate in certain frequency and amplitude. Hardware-in-the-loop simulations were conducted to verify the effectiveness of the two control strategies mentioned above and to evaluate them.

High altitudes have a significant effect on the real driving emissions (RDE) of vehicles due to lower pressure and insufficient oxygen concentration. In addition, type approval tests for light-duty vehicles are usually conducted at altitudes below 1000 m. In order to investigate the influence of high altitude on vehicles fuel economy and emissions, RDE tests procedure had been introduced in the China VI emission regulations. In this study, the effect of altitude on fuel economy and real road emissions of three light-duty gasoline vehicles was investigated. The results indicated that for vehicles fuel economy, fuel consumption (L/100 km) for the tested vehicles decreased while the mean exhaust temperature increased with an increase in altitudes. Compared to near sea level, the fuel consumption (L/100 km) of the tested vehicle was reduced by up to 23.28%.

It has been revealed by researches that lubricant properties have a great effect on the low-speed pre-ignition (LSPI) frequency in downsizing turbocharged direct-injection engines which are developed for better fuel economy. Droplets of lubricant or lubricant-gasoline mixture are considered to be the potential pre-ignition sources. Those droplets fly into the combustion chamber and ignite the gasoline-air mixture. To study lubricant droplets fundamentally, a novel set of droplet auto-ignition system is designed based on a Dibble Burner for this experiment. Influences of metallic additive contents, viscosities, lubricant diluted with gasoline and waste lubricant on the ignition delay of droplets are investigated by testing 12 groups of lubricants or lubricant-gasoline mixture. The equivalent diameter of each droplet generated by micro-syringes is around 2.1 mm. The co-flow temperature varies from 1123 K to 1223 K, and the experiments are carried out at atmospheric pressure.

BBW (Brake-by-wire) can increase the vehicle safety performance due to high control accuracy and fast response speed. As one solution of BBW, the novel Integrated-electro-hydraulic brake system (I-EHB) is proposed, which consists of electro-hydraulic booster and hydraulic pressure control unit. The electro-hydraulic booster is activated by an electric motor that driving linear motion mechanism to directly produce the master cylinder pressure. With electro-hydraulic booster as an actuator, the hydraulic pressure control problem is a key issue. Most literatures deal with the pressure control issue based on the feedback pressure signal measured by pressure sensor. As far as the authors are aware, none of the proposed techniques takes into account the pressure sensor unequipped BBW. In this paper, there is no pressure feedback signal, but there is only position feedback signal measured by position sensor for control law design.

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.

Due to the advantages of low weight, low emissions and good fuel economy, downsized turbocharged gasoline direct injection (GDI) engines are widely-applied nowadays. However, Low-Speed Pre-Ignition (LSPI) phenomenon observed in these engines restricts their improvement of performance. Some researchers have shown that auto-ignition of lubricant in the combustion chamber has a great effect on the LSPI frequency. To study the auto-ignition characteristics of lubricant, an innovative single droplet auto-ignition test system for lubricant and its mixture is designed and developed, with better accuracy and effectiveness. The experiments are carried out by hanging lubricant droplets on the thermocouple node under active thermo-atmosphere provided by a small “Dibble burner”. The auto-ignition process of lubricant droplets is recorded by a high-speed camera.

The characteristics of three-way-catalyst during engine start process were investigated based on a simulated start/stop test system for HEV application. Although the catalyst has already reached its light-off temperature, the conversion efficiency is poor during engine start process due to the deviation of lambda from stoichiometric. The high concentration hydrocarbon emission spike can be stored by catalyst substrate temporarily, then it is released. This dynamic process decreases the conversion efficiency for the following exhaust hydrocarbon emission. When the initial temperature of catalyst substrate before engine start increased from 150°C to 400°C, the conversion efficiency for both the hydrocarbon and NO are increased.

The First Firing Cycle (FFC) is very important at cold-start. Misfiring of the first firing cycle can lead to significant HC emissions and affect the subsequent cycles. This paper presents an investigation of characteristics of transient NO emissions in a small LPG SI engine with electronic gaseous injection system. To determine the optimal excess air coefficient ( λ=[A/F]/[A/F]stoic) of the first firing cycle, the emission of instantaneous NO was proposed as a useful criterion to judge if the combustion is occurred or not. A fast response NO detector- Cambustion fNOx400, based on the chemiluminescence's (CLD) method, has been employed to measure continuous, transient emissions of NO during the first firing cycle in the exhaust port of the engine. At the same time, the transient cylinder pressure, instantaneous crankshaft speed of the engine and engine-out HC emissions were measured and recorded.

To meet the request of China National 6b emission regulations which will be officially implemented in China, firstly including the RDE emission test limits, the transient emissions on real road condition are paid more attention. A non-plug-in hybrid light-duty gasoline vehicles (HEV) sold in the Chinese market was selected to study real road emissions employed fast response NOx analyzer from Cambustion Ltd. with a sampling frequency of 100Hz, which can measure the missing NO peaks by standard RDE gas analyzer now. Emissions from PEMS were also recorded and compared with the results from fast response NOx analyzer. The concentration of NOx emissions before and after the Three Way Catalyst (TWC) of the hybrid vehicle were also sampled and analyzed, and the working efficiency of the TWC in real road driving process was investigated.

The CO2 reduction request for automotive industry promotes the efforts on the engine thermal efficiency improvement. The goal of this research is to improve the thermal efficiency on an extremely downsized 3-cylinder 1.0 L turbocharged gasoline direct injection engine. Effects of compression ratio, exhaust gas recirculation (EGR), valve timing and viscosity of oil on fuel economy were studied. The results show that increasing compression ratio, from 9.6 to 12, can improve fuel economy at relative low load (below 12 bar BMEP), but has a negative effect at high load due to increased knock intensity. EGR can significantly reduce the pumping loss at low load, optimize combustion phase and reduce exhaust gas temperature. Therefore, the fuel consumption is reduced at all test points. The average brake thermal efficiency (BTE) benefit percentage is 3.47% with 9.6 compression ratio and 5.33 % with 12 compression ratio.

According to the requirements of two-wheel vehicle's future market and the characteristic of urban road conditions in China, the advantages and disadvantages of three basic configurations for the Hybrid Electric Vehicle are compared, finally, the serial hybrid configuration is chosen to be applied to hybrid Electric Moped solution. The selection principle of main components of this hybrid powertrain system includes ICE, generator, battery and hub motor, and the optimal match for performance parameters of these components are introduced in this paper. Then, a hybrid system model is established based on AVL-CRUISE. The simulations of fuel efficiency and exhaust emissions for both serial hybrid moped and conventional motorcycle is offered.