全液压制动系统管路布置对车辆制动性能的影响

统元件的自身结构特性，其余大多是由于在系统设计与管路布置时未考虑液压制动系统自身的特点，而是按照常规液压系统的设计原则布置管路造成的，致使制动系统无法发挥其应有的功能和优势。国产某井下无轨轮式车辆全液压制动系统出现的问题应，继续踩下踏板至极限位置后，系统迟滞约3s后才开始响应，使驾驶人员难以准确控制制动距离；其次是制动器一旦响应，制动力矩急速上升至最大，造成车辆紧急制动，制动系统无法实现驾驶人员通常用于控制速度的点制动减速过程。最为关键的问题

作者简介：林慕义（1964—），男，福建省福州市人，教授，博士，研究方向：工程车辆设计理论。

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大，设计时可不考虑其弹性的影响，而制动软管一般采用内含钢丝网的液压软管，与硬管相比在制动过程中其径向膨胀量较大，此时制动油液的体积弹性模量已无法反映制动软管内部的液流特性，须考虑管路膨胀的等效体积弹性模量[2]。

选用液压软管会产生部分流量损失并造成时间弹性模量，ρ为油液密度。

由此说明轮缸压力变化滞后时间与制动管路的布置、油液的等效体积弹性模量有关。对于液压制动软管，其压力传递速度远小于硬管。

液压制动系统中的管接头、弯头、配液板等也会产生局部压力损失，这些损失对系统造成的影响较

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合制动系统设计的，改用全液压制动后，未调整制动器空行程，较大的轮缸容积使空行程持续时间增加。

为验证上述分析并进行改进设计，对该车制动

系统一些关键位置的制动压力响应特性进行了测试，部分测试结果如图2～图4所示。

1——

—C2出口处2——

—P2入口处

图4蓄能器C2出口与制动阀P2入口压力比较

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此外，全液压制动系统在使用中出现的踏板反弹、无点制动等现象主要与制动阀自身结构与特点有关。压力反馈式制动阀的原理是：制动时，阀芯受踏板弹簧的作用向下移动，首先关闭回油口，而后将蓄能器出口与制动轮缸的压力口相连通，踏板力通过踏板弹簧与制动压力的平衡决定制动压力的大

[4]宋鸿尧，丁忠尧.液压阀设计与计算[M].北京：机械工

业出版社，1979.

通信地址：北京市海淀区清河小营东路12号北京信息科技大学机电学院（100085）（收稿日期：2008-09-08）

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Construction Machinery and Equipment

Vol．40No．1

Abstracts in English

The cause of overlapped multi-layer asphalt straying and its effect on spraying accuracy and evenness and factors influencing the quality of overlapped multi-lay-er,including the height between nozzle and ground, nozzle spacing,spraying sector angle and nozzle mount-ing angle,are studied using probability statistics theory and experiment.Rational overlapped multi-layer num-bers and method to improve overlapped multi-layer spraying quality are presented.A prototype of asphalt spraying system is designed and field test is carried out. Results of experiment show that the asphalt spraying accuracy when using overlapped multi-layer spraying is evidently higher than that without overlapping. Keywords:Overlapped multi-layer spraying

Asphalt spraying accuracy

Influencing factors

Impact of Fully Hydraulic Braking System Piping Layout on Vehicle Braking Performance

The requirements for fully hydraulic braking system are different from conventional hydraulic braking system. Taking the problems occurring during design and re-search of underground trackless wheel vehicles as ex-amples,the impact of piping layout of braking system on vehicle performance is tested and analyzed and corre-sponding improvements are suggested,which achieved predicted effects via implementation.It provides a refer-ence to the application of fully hydraulic braking system to domestic construction vehicles.

Keywords:Fully hydraulic braking

Piping layout

Braking performance

Monte Carlo Finite Element Analysis for the Cutter Disk of Shields

A math model for ANSYS numerical simulation of the cutter disk is created via an analysis in the mutual ac-tion between shield cutter disk and its cutters and the working face.Because of the randomness of the mutual action between cutter disk and working face,the major factors to be studied are treated as random input vari-ables and the intended results as output variables.That is,by setting elastic resistance factors as random input variables and mutual action between cutter disk and working face as random variables,Monte Carlo finite el-ement procedure is applied to simulate the statistic val-ues of the mutual action between cutter disk and its cut-ters and the working face,hence to provide an effective approach for the analysis on the applied force on the roller cutters and cutter layout on cutter disk.The method and results both present certain meaning for the design of shield cutter disk and shield operation in sub-ways.

Keywords:Shield Cutter disk

Monte Carlo finite element analysis

Application Analysis of TB593E/TS Double Shield TBM Cutters

Qinghai Yindajihuang Project is a large area-across, water transfer project adopting TB593E/TS Double Shield TBM from Germany for construction.Because the long distance tunnel and complicate geological condi-tions,several cutter problems occurred during the con-struction and construction has been seriously restricted. Cutter management as the foregoer of TBM equipment management,the operation of cutter affects greatly the TBM.Through design of the cutter disk and cutters for TB593E/TS Double Shield TBM,and specific analysis of operation problems during construction,the regularity of cutter replacement in normal operation is summarized by statistics.Through statistics of abnormal cutter dam-ages and analysis aiming at cutter disk design and cutter damage phenomena,the cause of cutter damages is studied.Ideas for improving cutter disk design of Dou-