Longitudinal train dynamics of electric multiple units under rescue

Once operating trains are disabled on the railway lines,an efficient manner is to utilize the train for train rescue.Owning to the different train and coupler types,it is difficult to formulate uniform regulations for train to train rescue.In this paper,the longitudinal train dynamics of electric multiple units under rescue were analyzed by field and laboratory tests.The angling behavior of the brakinginduced coupler under compressed in-train forces was analyzed.A dynamic model for the train and draft gear system was developed considering accurate boundary limitations and braking characteristics.The safety indices and their limits for the coupled rescue train were defined.Thedynamic evaluations of different train to train rescue scenarios were analyzed.It is indicated that the coupler vertical rotation occurs during the emergency braking applied by the assisting train.The vertical force components of intrain forces lead to the carbody pitch behavior and even cause local destructions to the coupler system.The carbody pitch motion can arise the inference of in-train devices.Based on the safety evaluation of train and coupler system,the regulations for typical train to train rescue scenarios were formulated.

Investigations on lubrication characteristics of high-speed electric multiple unit gearbox by oil volume adjusting device

In this paper,a numerical simulation model of the flow field in a gearbox with an oil volume adjusting device is established for the first time to study its influence on the lubrication characteristics of a high-speed electric multiple unit(EMU)gearbox.The moving particle semi-implicit(MPS)method is used to numerically simulate the internal flow field of the gearbox of the high-speed EMU under working conditions.The effects of the velocity of the high-speed EMU,the immersion depth,and the oil sump temperature on the power loss of the gears and the lubricant quantity of each bearing are studied and provide an effective tool for the quantitative evaluation of the lubrication characteristics of the gearbox.The lubrication characteristics of the gearbox under different working conditions are studied when the oil volume adjusting device is closed and opened.The results show that the oil volume adjusting device mainly changes the amount of lubricant stirred by the output gear by changing the flow rate of lubricant from the cavity pinion(Cavity P)to the cavity gear(Cavity G),and thus affects the power loss of gears and the lubricant quantity of each bearing.

Application and development of friction stir welding technology in high speed EMU manufacturing

The application status of friction stir welding technology is introduced,and the application research of advanced FSW technology in the manufacture of high-speed electric multiple unit aluminum alloy body is analyzed,including the application of traditional friction stir welding technology to a combination of a lap joint and butt joint,and butt joint of large thick plate by both sides process,also introduces bobbin-tool friction stir welding to a butt joint and three-dimensional space curved friction stir welding to T-joint. At the same time the future development trend of new FSW technology derived from traditional FSW technology in rail vehicle manufacturing industry is put forward. As the fast developing of critical technology used on railway vehicles,quick applying advanced welding technology will affect products quality,manufacturing cost and production cycle time directly,and it certainly will be one of the approaches to develop markets by all the railway vehicles manufacturing enterprises.

Analysis of torque transmitting behavior and wheel slip prevention control during regenerative braking for high speed EMU trains

The wheel-rail adhesion control for regenerative braking systems of high speed electric multiple unit trains is crucial to maintaining the stability,improving the adhesion utilization,and achieving deep energy recovery.There remain technical challenges mainly because of the nonlinear,uncertain,and varying features of wheel-rail contact conditions.This research analyzes the torque transmitting behavior during regenerative braking,and proposes a novel methodology to detect the wheel-rail adhesion stability.Then,applications to the wheel slip prevention during braking are investigated,and the optimal slip ratio control scheme is proposed,which is based on a novel optimal reference generation of the slip ratio and a robust sliding mode control.The proposed methodology achieves the optimal braking performancewithoutthewheel-railcontactinformation.Numerical simulation results for uncertain slippery rails verify the effectiveness of the proposed methodology.

Development and engineering application of integrated safety monitoring systems for China’s high-speed trains

With the improvement of the running speed of China’s high-speed trains,the demands for running status monitoring and security assurance of High-speed Electric Multiple Units(EMU)have increased significantly.However,the current safety monitoring systems are independent,which is not conducive to the comprehensive monitoring and information sharing of the whole vehicle.The temperature monitoring of running gear is insensitive to early failures.How to develop a train operation safety monitoring system with strong engineering implementation and high integration is a key problem to be solved.For the monitoring of running stationarity,frame stability and running gear health of China’s high-speed trains,an integrated safety monitoring system framework is designed,and the logic and algorithm for the diagnosis of stationarity,stability and health states of rotating parts are constructed.Monitoring software which fused the temperature,high and low frequency vibration data is developed,and the design and installation of the vibration temperature composite sensors are completed.The research results have realized the integration and comprehensive processing of multiple monitoring systems,completed the improvement from single component and vehicle-level safety monitoring to multi-system,train-level and interactive monitoring.In the process of real vehicle application,the developed monitoring system acquires the vehicle operation status data accurately and in real time.The constructed diagnosis algorithm and logic evaluates the vehicle operation status accurately and in a timely manner,and avoids the progression from fault to accident.The research results show that the integrated safety monitoring system can provide technical support for train operation safety.