Elastic mastic buffer for the hottest urban rail c

Elastic mastic buffer for urban rail cars and its application

Abstract: the performance advantages and working principle of elastic mastic and elastic mastic buffer for urban rail are emphatically introduced

key words: urban rail, elastic mastic, buffer

Introduction

the development of urban rail transit system has become the only way to solve urban traffic problems in China. The industrialization of urban rail transit vehicles is one of the important work of China's locomotive and rolling stock industry, and the localization of key parts of rail vehicles is an important guarantee for the industrialization of urban rail transit vehicles

buffer is one of the important components of urban rail transit vehicles. Its function is to mitigate vehicle impact and reduce vehicle longitudinal impulse. The performance of the buffer directly affects the driving safety and passenger comfort. Therefore, countries all over the world attach importance to the development and research of the buffer with excellent performance, which is the special Medal of the merchants signing the "Green Plan"

at present, the typical buffers in China include rubber buffer, grease lubricated ring spring friction buffer and hydraulic buffer, but they have the disadvantages of poor low-temperature performance and aging resistance, short service life, complex manufacturing and maintenance process, high cost, heavy self weight and high requirements for manufacturing and processing accuracy, so they are difficult to be widely promoted

1 introduction to elastic mastic

buffer medium used for the study of elastic mastic buffer elastic mastic material is a kind of high viscosity, compressible, flowable unvulcanized silicone compound, which has high stability in the range of -80 ~ +250 ℃, and is odorless, non-toxic, and pollution-free to the environment and personnel. It has solid 1. Main specifications: 100kN and liquid 2 states. It is an ideal buffer medium material for coupler buffer. Without the action of the restoring spring, the restoring return of the buffer can be realized by using its high elasticity; Using its compressibility to realize the compression stroke of the buffer; Using its good fluidity can realize the large capacity and low impedance of the buffer. The flow viscosity of this material can be adjusted according to the actual use needs, and its kinematic viscosity can be dozens or even hundreds of times larger than that of ordinary hydraulic oil. This simplifies the problem of difficult sealing of hydraulic buffer. If this material can solve the production process problems, its cost will not be higher than $60/kg, and an urban rail car will not produce a strong neck, and the amount of elastic mastic will not exceed 3kg under the condition that the vehicle buffer capacity is 15kj. Therefore, the price of elastic mastic material can meet the market requirements for the promotion of elastic mastic buffer

2 basic structure principle of elastic mastic buffer

the elastic mastic buffer is mainly composed of piston, piston rod, cylinder head, cylinder block, charging valve, etc. (see Figure 1). Its working principle is: put the elastic mastic material into the buffer body, and apply a certain preload as required. When the piston rod of the buffer is under a certain pressure, the elastic mastic is compressed to produce impedance force, The throttling effect of the annular clearance (or orifice) of the piston and the compression deformation of the elastic mastic material are used to absorb the impact energy. Due to the characteristics of the mastic material, the greater the pre pressure of the elastic mastic and the movement speed of the piston, the greater the impedance, which is conducive to improving the capacity of the buffer under large impact, that is, the greater the impact, the greater the capacity of the buffer; The smaller the impact, the smaller the capacity of the buffer. When the external force acting on the piston rod is withdrawn, the elastic mastic expands by itself and pushes the piston back to its original position. In this process, the understanding of the course content by the elastic mastic will have important practical significance. The mud material flows back to its original position through the annular gap (or orifice) of the piston at a slow speed to realize the return action of the buffer

the head of the buffer can be connected with the coupler by flange connection or by paired connecting rings. Rubber ball joints need to be installed at the tail to adjust the height difference between the couplers caused by the line curve

3 analysis of standard conditions of elastic mastic buffer

the technical parameters of the buffer should match the vehicle, and the technical parameters of the buffer are different for vehicles in different technical states. Whether the buffer is good mainly depends on whether its performance matches the vehicle and whether the longitudinal impact of the train can be minimized to improve the comfort of passengers. The force displacement curve of elastic mastic buffer is shown in Figure 2

3.1 rated capacity of elastic mastic buffer rated capacity

is the maximum impact or compression kinetic energy that the buffer can accept within the range of rated stroke and impedance force, which is the basic index of the buffer. For example, when the shunting speed of Shanghai Metro is 5km/h, the vehicle buffer capacity is 18.7kj

3.2 rated impedance force of elastic mastic buffer

the rated impedance force has a great impact on the longitudinal acceleration of the vehicle, the service life of vehicle parts, and the comfort of passengers. Generally, the smaller the better. However, sometimes due to limited conditions, in order to meet the requirements of absorbing energy and rapid return of the buffer, the minimum impedance force should not be too small (for example, the rated impedance force of the buffer of Shanghai metro vehicles is 590kn)

3.3 rated stroke of elastic mastic buffer

rated stroke is one of the important parameters of buffer. Generally speaking, a large rated stroke of the buffer is beneficial to improving the rated capacity of the buffer and reducing the rated resistance. For example, the buffer of Shanghai metro vehicles is 58mm, and the buffer of domestic urban rail is 73mm. Its size is often restricted by vehicle construction factors

3.4 initial pressure of elastic mastic buffer

initial pressure is one of the important parameters of buffer. According to relevant information, the initial pressure of the buffer affects not only the longitudinal acceleration of the train, but also the longitudinal vibration frequency of the vehicle. The greater the initial pressure of the buffer, the greater the longitudinal vibration amplitude and frequency of the vehicle, and the worse the longitudinal comfort of passengers. Therefore, the smaller the initial pressure of the buffer, the better. However, limited by the manufacturing level of buffer in China, it is generally about 15kn ~ 25kn

3.5 the absorption rate of the buffer

the absorption rate is the ratio of the energy consumed by the buffer in an impact to the energy received. The size of the absorption rate of the buffer indicates its ability to attenuate the impact kinetic energy. The absorption rate of the buffer is the ratio of the sum of damping energy consumption and elastic energy consumption to the total energy (see Figure 2). Generally, the larger the better. The absorption rate of buffer for urban rail vehicles is about 80%

4 conclusion

compared with ordinary buffers, elastic mastic buffers have the advantages of large capacity, small impedance, small volume, light weight, long maintenance cycle and so on. Under the same capacity, it can reduce the weight by 30% - 50%, and the maintenance cycle is as long as 10 years. With the development of urban rail transit and the improvement of passenger comfort requirements, elastic mastic buffers will be widely used

References:

[1] Li Kexing, Lin le Experimental research on elastic mastic buffer [j] Railway rolling stock, 1996, № 10, 23 ~ 24

[2] Zhang Zhenmiao Urban rail transit vehicles [m] Beijing: China Railway Press, 1998 (end)