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To improve the vehicle diesel engine performance at part-load operation, experiments on sequential turbocharging system used in a vehicle diesel engine are investigated in this paper. The brake specific fuel consumption and smoke emission of diesel engine are measured in four schemes: with the based turbocharger, with a small turbocharger, with a big turbocharger, with both small and big turbochargers. Then, a new turbocharging method named three-phase sequential turbocharging system with two unequal size turbochargers is presented by analyzing and comparing the experimental results. The experiment on a vehicle diesel engine with three-phase sequential turbocharging system shows that the brake specific fuel consumption and the smoke emission are reduced observably in complete engine speeds range, especially in the low speed operation. Finally, the transient performances of three-phase sequentially turbocharged vehicle diesel engine are analyzed by experiments.

During braking, energy regeneration for hybrid electric vehicles (HEV) is an important technique to improve their fuel economy and extend their driving range. Due to the effect of regenerative braking torque added by the electric motor, the control logic of the braking system should be adjusted. This paper presents a control strategy for an HEV braking system, which calculates the optimal target wheel slip ratio based on vehicle dynamic states; a fuzzy logic approach is applied to maintain the optimal target slip ratio so that the best compromise between hydraulic braking torque and regenerative braking torque can be obtained for the vehicle. This control strategy is implemented with an 8-DOF nonlinear vehicle model and a “Magic Formula” tire model; the simulation results show that the proposed strategy is robust and effective.

Electric power steering systems (EPS) greatly improve fuel performance over conventional hydraulic power steering systems, and therefore being increasingly adopted. However, it is very important to evaluate the mechanical noise and to identify the correct noise source in steering systems, because an EPS has vibration sources such as at the motor gear reducer, manual gears and intermediate joints. In order to identify the noise source, a technique based on time-frequency analysis using the wavelet transform (WT) has been focused on which uses a mother wavelet (MW) that is derived mathematically. The measured signal is adopted as the MW. In this study, applying this method to time-varying signals, a new concept of the Wavelet Instantaneous Correlation Value (WICV) is discussed and is used to identify the noise source.

By changing the top-land radial clearance, this paper presents the effect of the piston crevice on the transient HC emissions 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. At the same time, the transient cylinder pressure and instantaneous crankshaft speed of the engine were measured and recorded. The results show that increasing 50% crevice volume leads to 25% increase of HC emissions in the lean region and 18% increase of HC emissions in the rich region, however, the 50% increase of crevice volume contributes to 32% decease of HC emissions in the stable combustion region. For LPG SI engine, the HC emissions of the first firing cycle during cold start are relatively low in a wide range of the excess air ratio.

To optimally allocate control authorities to co-existing active actuators, an integrated chassis controller with main/servo-loop structure is designed to coordinate direct yaw moment control and active steering. Firstly, a sliding mode controller in the main-loop calculates the desired stabilizing forces. Then in the servo-loop, by directly considering limits of road friction and actuators, a quadratic programming based control allocation approach is adopted to reasonably and optimally distribute these deisired forces to tire actuator actions. Co-simulation of Matlab/Simulink and Carsim clarifies that the proposed controller could significantly improve vehicle handling performances.

During cold start of DI diesel engine, exhaust gas comprises a great deal of unburned hydrocarbon, fuel vapor, and product of partial oxidation reaction. If these compositions are reintroduced into cylinder by EGR, the positive effects may shorten ignition delay, and thus promote ignition. Furthermore, considering thermal effect of EGR and its minor dilution effect during cold start, the combustion performance of cold start could also be promoted through introducing EGR. Through experiments conducted on a 135 single cylinder DI diesel engine, effects of EGR on combustion and emission performance during cold start process were investigated. Comparison of combustion performance between cold start processes with and without EGR suggested that it is an effective measure to improve cold startability of DI diesel engine by controlling EGR system during cold start.

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.

Multi-energy management strategy plays an important role in fuel economy improvement for hybrid electric vehicles. For the integrated starter generator hybrid electric car in this paper, multi-energy management becomes torque distribution. The novel torque distribution strategy is proposed to minimize the powertrain equivalent specific fuel consumption. The distribution results are essentially three-dimensional look-up table-based control according to the vehicle torque request, the internal combustion engine speed and the ultracapacitor voltage after off-line calculation. Simulations results show that potential fuel economy improvement is achieved relative to the conventional logic threshold control strategy.

A Steer-by-wire (SBW) system, which has no mechanical linkage, is expected to support the driver even in critical situations so as to improve collision safety and cockpit design flexibility. We have shown the effectiveness of driver assistance using an active steering control integrated with active braking control.[1] This is a case of normal driving without any vital component failures. The SBW system failure, however, can lead to an unsafe driving situation. A highly redundant design reduces the SBW failures but complicates its design and increases cost, volume and weight. This paper proposes a new fault-tolerant architecture to cope with the SBW failure. This is based on an integrated control by SBW, active braking, and driving torque distribution. A feasibility study is made using a driving simulator experiment during front obstacle avoidance under failed SBW.

We have developed a new active-front-steering system which contributes to the vehicle safety improvement. This system includes two motors and differential gear unit in one body. It makes possible to compensate steer angle and control reactive torque simultaneously. This means driver assistance control without interference on driver. This concept has a potential to omit tuning process on each vehicle, and reduce weight and cost. We have proved the effect of driver assistance control by this system.

This paper presents the development of an electronic control LPG gas injection system and its application in a small SI engine. The tests results show that the developed LPG gas injection system can meet the needs for the goal of high engine power output and low exhaust emissions based on the engine bench tests. With the LPG electronic gas injection system, the air-fuel ratio can be optimized based on the requirements and CO and NOx emission levels are decreased significantly compared with the LPG mechanical mixer fuel supply system, based on the same HC emission levels. With the new gas phase LPG electronic control injection system, the HC emission level is controlled below the 300 ppm under most engine conditions and under 200 ppm when the engine speed is over 3000 r/min. The NOx emission level is under 2600 ppm in the whole range of engine operation conditions and is decreased by 2000 ppm compared with the LPG mechanical mixer system.

A flat neural network is designed for the on-line state prediction of engine. To reduce the computational cost of weight matrix, a fast recursive algorithm is derived according to the pseudoinverse formula of a partition matrix. Furthermore, the forgetting factor approach is introduced to improve predictive accuracy and robustness of the model. The experiment results indicate that the improved neural network is of good accuracy and strong robustness in prediction, and can apply for the on-line prediction of nonlinear multi input multi output systems like vehicle engines.

This paper presents an experimental study of the emission characteristics of a small Spark-Ignited, LPG engine. A single cylinder, four-stroke, water-cooled, 125cc SI engine for motorcycle is modified for using LPG fuel. The power output of LPG is above 95% power output of gasoline. The emission characteristics of LPG are compared with the gasoline. The test result shows that LPG for small SI engine will help to reduce the emission level of motorcycles. The HC and CO emission level can be reduced greatly, but NOx emissions are increased. The emission of motorcycle using LPG shows the potential to meet the more strict regulation.

The purpose of this study was to quantifiably evaluate driver mental fatigue using the power spectral analysis of the heart rate variability (HRV). The quantitative detector of driver fatigue can present appropriate warnings and help to prevent traffic accidents. A simulation creating driver mental workload was set up using vigilance, considered to be an accurate assessment of driver mental workload, to evaluate a driver's performance. In the experiment eight healthy male subjects were required to perform a vigilance task for 90 minutes. The physiological variables for evaluating driver mental load were spectral values of heart rate variability (HRV). As a result HRV showed a high correlation with driver mental fatigue.

This paper presents a study of LPG lean burn in a motorcycle SI engine. The lean burn limits are compared by several ways. The relations of lean burn limit with the parameters, such as engine speed, compression ratio and advanced spark ignition etc. are tested. The experimental results show that larger throttle opening, lower engine speed, earlier spark ignition timing, larger electrode gap and higher compression ratio will extend the lean burn limit of LPG. The emission of a LPG engine, especially on NOx emission, can be significantly reduced by means of the lean burn technology.

In designing an automobile seat, it is important to minimize the fatigue experienced by the driver resulting from long-term sitting. In this study eight healthy male subjects participated in two group experiments that were A-group and B-group. Acupoints combined with magnetism stimuli were put on to the subjects for reducing postural fatigue in B-group during the simulated driving. The surface electromyography (sEMG) of muscle activity at L4/L5 as well as subjective self-reporting on fatigue were recorded and tested. Analyzing and comparing the EMG median frequency and the subjective evaluations between two groups a conclusion that acupoints combined with magnetism stimuli could reduce the driver postural fatigue was drawn.

In designing an automobile seat, it is important to minimize the fatigue experienced by the driver resulting from long-term sitting. In this study eight healthy male subjects participated in two group experiments that were A-group and B-group. Acupuncture was put on to the subjects for reducing postural fatigue in B-group. The sEMG of muscle activity at L4/L5 as well as subjective self-report on fatigue were recorded and tested. By analyzing and comparing the EMG median frequency and the subjective evaluations between two groups a conclusion was drawn that acupuncture could reduce the postural muscle fatigue effectively.

This study investigates the cycle performance and potential advantages of the replacement of fin-and-tube evaporator with parallel flow micro-channel evaporator, in R134a roof-top bus air conditioner (AC) system. The heat exchangers for bus AC system are featured by a stringent space height limitation. The configuration of inclined four piece or six piece micro-channel evaporators was proposed to satisfy this space requirement, instead of original two piece fin-and-tube evaporators. Additionally, the individual superheat control method with thermostatic expansive valve (TXV) in each evaporator was adopted to improve refrigerant distribution. Three kinds of micro-channel evaporators were designed and equipped in an 8-m roof-top bus AC system. Except the replacement of evaporators, TXV and connecting pipes, other cycle components were kept same.

In the recent years, the interaction between human driver and Advanced Driver Assistance System (ADAS) has gradually aroused people’s concern. As a result, the concept of personalized ADAS is being put forward. As an important system of ADAS, Lane Keeping Assistance System (LKAS) also attracts great attention. To achieve personalized LKAS, driver lane keeping characteristic (DLKC) indices which could distinguish different driver lane keeping behavior should be researched. However, there are few researches on DLKC indices for personalized LKAS. Although there are many researches on modeling driver steering behavior, these researches are not sufficient to obtain DLKC indices. One reason is that most of researches are for double lane change behavior which is different from driver lane keeping behavior. The other reason is that the researches on driver lane keeping behavior only provide model structure and rarely discuss identification procedure such as how to select suitable data.

Rapid pressure build-up before acquiring the engine phase position is necessary to improve the start performance for a common rail diesel engine. This paper presents a simulation model to describe the pressure build-up process of the DENSO HP0-MD high-pressure pump, with the two pressure-control-solenoid-valves (PCV) are frequently driven in sequence. As the fuel is pumped only when one PCV is energized in its corresponding plunger supply stroke, simulation studies are carried out to analyze the pressure build-up effect of different driving frequency, and the 30Hz frequency is selected as the optimal driving frequency to achieve about 80% fuel supply efficiency for the normal cranking speed range. Additionally, when only the crankwheel signal is useful, a novel method, which checks whether the rail pressure rises in a special PCV energizing zone, is designed to assistant ascertain engine phase.