【作者】 张晓军；

【导师】 刘延俊；

【作者基本信息】 山东大学 ， 机械制造及其自动化， 2011， 硕士

【摘要】 本文首先对叉车的行走部分在结构上进行优化,将传统的机械传动或液力传动的形式设计简化为液压驱动的形式。根据叉车要实现启动、制动、换向和调速的要求,在设计时采用了变量泵---定量马达的闭式油路,马达输出转矩由负载决定,不因调速而发生变化,调速范围大,能使叉车在承受最大负载时能在最高车速范围内平稳地行走。转速的调节是通过调节泵的排量来实现的。由于液压系统具有传递功率密度大、启动换向平稳、易于频繁操纵、易于实现自动控制等特点,简化了叉车行走部分的结构,除了满足车辆平稳地启动、制动外,还能方便地实现无级变速,便于操作。采用泵—马达式容积调速的闭式油路,简化了能量传递的结构,提高了传递效率。经过结构优化后的叉车各部分都由液压装置驱动,为叉车的生产和检测带来了方便。由于在液压系统中,出现的故障现象和原因之间表现出明显的的非线性特征,许多故障征兆和故障原因用模糊概念描述比较合理。在各种液压系统中,由于各系统及元件具有一定的相似性,所以各系统及元件的故障具有一定的共同特点,并且在这一领域积累了大量的专家知识,为发展液压系统的故障诊断专家系统创造了条件。全液压叉车的液压系统分为五个部分：行走液压系统、转向液压系统、升降液压系统、倾斜液压系统及属具液压系统。每个液压系统都是由若干个元件和回路组成的,本文以转向系统为例,利用模糊诊断的方法对液压系统出现的各种故障症状进行排序和归类,利用故障原因的权重系数来建立隶属度,采用模糊推理的形式进行分析,找出故障原因；或者利用测量仪器或传感器获得的故障参数对故障原因进行分类,并将参数误差模糊化,建立模糊关系矩阵,采用模糊控制的形式进行分析,找出故障原因。更多还原

【Abstract】 In this article forklift walking part optimized in structure is first introduced. The traditional mechanical or hydrodynamic transmission is simplified and designed for hydraulic drive form. According to the requirements of forklift starting, braking, reversing and changing speed, the design of the variable pump quantitative motor closed circuit is adopted. That mean, that motor output torque is determined by the load not the speed change. Speed ranges widly, and the forklift can be running smoothly under the maximum speed range in the maximum load. The speed is adjusted by the pump displacement. Because the hydraulic system has the characteristics of high power-transmitted density, stable starting reverse, easily frequent operation and automatic control, etc., it simplifies the structure of forklift running part. It not only meets the requirements of vehicle smoothly starting and braking, but also can complete stepless speed change conveniently and gear reducing for good operation. Therefore, it simplifies the structure of energy transfer to adopt the pump motor speed closed type volume oil circuit.There are hydraulic drives in every part after the structure is optimized. It brings great convenience for the production and detection of forklift. There are many obvious nonlinear characteristics between fault phenomena and reason in the hydraulic system. So it is reasonable to describe the fault phenomena and reasons with fuzzy concepts. In all kinds of hydraulic systems, there are some common characteristics, as a result of certain similarities between systems and components. In this area, there are much expert experiences; it creates good condition for the development of fault diagnosis expert system. Full hydraulic forklift system consists of 5 parts, as below:walking hydraulic system, steering hydraulic system, lifting hydraulic system, inclined hydraulic system, belongings hydraulic system. Each hydraulic system is composed of some components and circuit. In this article it can sort and classify fault symptoms which are showed in the hydraulic system, using fuzzy methods, for example in steering system. Refer to the probability values caused by fault reasons to establish membership, then adopt fuzzy reasoning analyze the parameter error, at last find out the cause of the malfunction; or using the measuring instrument and the sensor to gain fault parameter changes, and make the error of parameters fuzzy, then adopt control analyze the parameter error to find out the cause of the malfunction.更多还原