Based on local environmental standards, vehicle types and traffic conditions, the prediction and analysis model of urban road traffic noise has been developed suitable for use in China. By classifying the vehicle into three types, the equivalent traffic flows of different vehicle types can be transformed by multiply the traffic flow of different vehicle types with corresponding weighing factor. Then the total equivalent traffic flow can be obtained by adding the equivalent traffic flows of different vehicle types. Considering the traffic speed, tire/road noise, and traffic flow, the equivalent traffic flows model can be established. Using variance analysis with the data of measured noise values and computed ones, the results show that the difference between calculated mean value and measure ones is 0.145 dB(A), in 95% confidence interval of the difference the maximal difference is between -0.054 to 0.343 at locations near the road carriage way. Finally, by frequence analysis using the measured values, it can be found that the maximal frequency is the equivalent noise level of 69 dB(A), which exceeds the ideal value far. and within the housing estate. The established model can simplify the problem of noise prediction as well as satisfy the requirement of precision, is suitable for use of prediction and analysis of road traffic noise.

The noise of high-pressure common-rail engine and the impact of engine performances on the noise are studied. The overall noise of the prototype is measured and sound sources are identified through acoustic scan, and it is found that the front-end face, the intake side, the exhaust side and the top of the engine are the main sources of noise. So, clad steel plate is installed on the gear room, and the heat baffle of exhaust pipe and the thermal shroud of turbine shell all use noise reduction parts. These measures are very effective. Then the impact of economy and power performances of the engine on the noise is studied by adjusting the parameters of high-pressure common-rail system, and it is found that increasing the fuel consumption and reducing the torque can reduce the noise. Research results show that the engine performances have great influence on the engine noise, and the noise can be reduced at the expense of a certain percentage of economy and power performance.

This paper presented the principle and method of calculation for the axial vibration based on Rayleigh differential method of crankshaft for a high speed diesel engine.At first,the internal combustion engine crankshaft was simplified to a continuous stepped shaft model and the kinetic formulas of shafts and masses were constructed.By means of the Lagrange formulation,the motion equation of torsional vibration and axial vibration were deduced.According to coupling principle and coupled excitation of the shafting system,a model of axial forced vibration can be constructed.Using a vector matrix,a single order or a whole system vibration can be analyzed.With a newly designed testing set-up,the axial vibration of the crankshaft at the free-end of a 4-cylinder diesel engine were measured.Compared with the practical measurement results,the calculated results are in agreement in main order.

In order to investigate the relation between the influencing factors and the sound radiation efficiency as well as the application of sound radiation efficiency in noise source identification,experiments on oil pans were conducted to research the influencing factors,such as required number of division,boundary condition,fixing condition,excitation mode and materials.Based on the experiments,the vibration of diesel engine parts was calculated.The results showed that the discrete calculation method(DCM) could be applied to some complex problems and the calculated sound power level(SPL) was 0.59 dB(A) higher than the measured sound power level,which indicated that it was accurate and feasible to adopt these results of sound radiation efficiency in noise source identification.

The secondary influencing factors of combustion noise mechanism under transient conditions of DI Diesel engines were studied.The secondary influencing factors of combustion noise were measured under steady and transient conditions.Under the same load and engine speed,the secondary influencing factors of combustion noise was analyzed including combustion chamber wall's temperature,fuel injection pressure,needle lift between transient conditions and steady conditions.The difference of the secondary influencing factors under the two conditions affects the aerodynamic load,high-frequency oscillation and combustion noise between steady and transient conditions.The secondary influencing mechanism of combustion under transient conditions at different fuel delivery advance angles is also studied.The result shows that wall temperature of combustion chamber,fuel injection pressure,maximum of needle lift and opening duration of needle lift under transient conditions are higher than those under steady conditions in the same load and engine speed,resulting in the difference in ignition delay,starting point of combustion,and fuel injection quantity between transient and steady condition,influencing the aerodynamic load and high-frequency oscillation of combustion pressure,making the difference of combustion noise between the two conditions.

This paper introduced the determinate and indeterminate load computing methods for main journal bearings in multi-cylinders ICE. Orbital path, minimum oil film thickness and maximum oil film pressure for some turbo-charged 4-cylinders ICE were calculated in different loads. The maximum load value calculated by indeterminate method was greater than the value given by determinate method, but the minimum value was less than the latter. Orbital path given by determinate method was different from the one by indeterminate method, so was the minimum oil film thickness and maximum oil film pressure. When the result of the computation was compared with that of experiment, it's found that the maximum oil film pressure and the minimum film thickness calculated by indeterminate method are quite close to the result of experiment. So, indeterminate load results should be used for accurate lubrication calculation.

This paper studies the relations between the objective physical characters and the subjective feeling from interior noise of vehicle cabin. Three types of vehicle real-time noises were recorded at various running speeds and later being subjectively evaluated in the testing room by pair comparison method. Meanwhile, the psychological assessment indexes were extracted, and experiments and analysis on influencing factors of annoyance index of interior vehicle cabin noise were made. The relationship between psychological assessment indexes and subjective annoyance index were studied by multiple regression method. The synthetic evaluation values obtained by linear combination of psychological acoustic indexes were in good agreement with the measured subjective assessment values, which can better explain the subjective assess values. Subjective evaluation of vehicle sound quality by the linear combination of psychological a-coustic assessment indexes is feasible.

This paper studies the influencing mechanisms of combustion noise in DI-Diesel engines under transient conditions,and investigates the testing methods under transient conditions.The reason for the difference in combustion noise between transient conditions and steady conditions at the same load and engine speed is clarified.The results show that there exist the differences in ignition delay,starting point of combustion and fuel injection amount between transient conditions and steady conditions.These would be due to the large values in combustion chamber wall's temperature,fuel injection pressure,maximum needle lift and lift duration under transient conditions rather than under steady conditions at same load and speed.The result shows that the aerodynamic load and high-frequency oscillation of combustion pressure result in their differences in combustion noise.

On the test basis,the paper investigates the relations among the maximal cylinder pressure,rate of pressure rise,heat release rate and the combustion noise obtained by designing a time window at the conditions of same speed and(different) load or of same load and different speed.The main component combustion noise concentrates in the frequency range of 400~(8 000 Hz) and is determined both together by the rate of pressure rise and the high-frequency oscillation of(combustion) pressure.The shape of heat release curve is closely related to the combustion noise.The result shows that the rate of pressure rise and the heat release are the main dynamic load factor that affects the combustion noise.

For studying the effect of the 3D vibration of crankshaft on the surface vibration of crankcase,the crankshaft torsion/axial/bending vibration testing devices are developed,and the signals of crankshaft 3D vibration and the surface vibration of crankcase are measured,with the partial coherence between them analyzed.The results show that the surface vibration of the crankcase is induced by 3-D vibration of the crankshaft.The torsional vibration of crankshaft induces the surface vibration of crankcase at some frequencies,commonly doubling that of the torsional vibration;The degree of partial coherence between axial vibration of crankshaft and surface vibration of crankcase is not very high except at some frequencies;while the bending vibration of crankshaft has higher partial coherence with the surface vibration of crankcase and is the major excitation source of surface vibration.

A statistical approach to evaluate the subjective perception of the annoyance caused by the vehicle noise was presented in this paper. After recording the noises of Sanfeng, Huali and Xiali at speeds of 30, 40, 50, 60, 70 and 80 km/h respectively, the annoyance of the vehicle noises was evaluated in the testing room using paired comparison method, and the sound quality metrics and subjective annoyance were then distilled. Loudness, sharpness, roughness, periodicity and impulsiveness were selected for each of the vehicle noises. By correlation analysis method, it can be found that loudness has a higher correlation (0.91) with annoyance than other parameters. Meanwhile, sharpness, periodicity, roughness and impulsiveness have correlation with subjective perception with correlation coefficients being 0.84, -0.82, 0.62 and 0.87, respectively. The result of multiple regression analysis shows that calculated annoyance obtained by the regression equation can explain the perceptual annoyance and the regressed evaluation model is feasible to evaluate the sound quality of vehicle.

This article studied the effect of transient conditions on combustion noise of DIDiesel engines.By developing testing technique and method of transient conditions and studying the difference of cylinder pressure,maximal cylinder pressure,rate of pressure rise,maximal rate of pressure rise,highfrequency oscillation of combustion pressure and cylinder pressure level in different frequency between transient conditions and steady conditions,the mechanism of difference between transient conditions and steady conditions was analyzed from the point of aerodynamic load and highfrequency oscillation of combustion pressure.The changing trend of rate of pressure rise was similar to the combustion noise,but there were differences existing in some conditions.It was the result of effect of the highfrequency oscillation of combustion pressure on combustion noise.The result shows that the aerodynamic load and highfrequency oscillation of combustion pressure working together result in difference of combustion noise in transient conditions compared with steady conditions in the same load and at the same rotation speed.

Subjective evaluations are investigated during engine working. A kind of new index to assess noise is given. Engine hearing characteristics are analyzed by using multivariate statistical methods. The important factors influenced on engine subjective impressions are loudness, impulsiveness , and frequency characteristics which can be quantified by A-weighted sound pressure level, kurtosis and high frequency level.

在分析城市道路交通噪声污染现状的基础上,介绍了国内外道路交通噪声预测和控制方法的研究进展,分析了交通噪声预测方面存在的问题,并讨论了我国交通噪声预测和控制的未来发展方向.

Wearing will be increased while improving speed and boosting the charge of cylinder according to the synthesis resolution model of tribology.Taking a 4-cylinder diesel engine as the calculating model,the conclusion is proved that correct while keeping the other operation condition fixed.Meanwhile,the paper had worked out that the increasement of rotating speed contributes more to the wear of crankshaft Journal and crankpin than the raising of pressure in cylinder.

本文从理论和实践两方面阐述了建立"现代化CAD教学基地"的必要性,详细介绍了CAD基地的管理方法以及如何由高素质的管理人员利用现代化的管理手段(结合多年教学及管理实践经验,独自开发研制的机房管理信息系统)对基地进行科学管理的体会.