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XXXXXXX毕业设计说明书题 目：全液压轮式装载机液压系统的设计 直动式溢流阀的设计专 业： 机械设计制造及其自动化 学 号： XXXXXXX 姓 名： XXXXXXX 指导教师： XXXXXXX（教授） 完成日期： 2012年5月27日 XXXXXXX 毕业论文（设计）任务书论文（设计）题目：全液压轮式装载机液压系统的设计 直动式溢流阀的设计 学号： XXXXXXX 姓名： XXXXXXX 专业： 机械设计制造及其自动化 指导教师：XXXXXXX 系主任： XXXXXXX 一、主要内容及基本要求 1、了解全液压轮式装载机的液压系统的工作原理及流程； 2、确定液压系统的主要参数，验算液压系统的性能； 3、用Auto CAD绘图软件绘制装配图，零件图； 4、设计说明书8000字以上，内容完整，计算准确； 5、外文翻译3000 左右字符； 二、重点研究的问题 动臂液压缸的设计，直动式液流阀的设计。 三、技术指标主要技术参数：额定斗容5，液压泵的理论流量=505.163，液压泵的功率=210.485转向泵流量61.2 油箱体积1520四、进度安排序号各阶段完成的内容 完成时间1查阅资料、调研1周2开题报告、制定设计方案2周3设计计算38周4CAD画图912周5整理说明书、外文翻译1314周6修改图纸和说明书15周7打印图纸、毕业设计答辩五、应收集的资料及主要参考文献1 液压传动与气压传动M。华中科技大学出版社。2008 杨曙东 何存兴主编2 现代工程图学M.湖南科学技术出版社。2000 周良德 杨世平 邱爱红等主编3 机械设计（第八版）M.高等教育出版社北京.2002 纪名刚等主编4 机械原理（第七版）M.西北工业大学机械原理及机械零件教研室.20065 工程机械液压系统设计计算（M）北京：机械工业出版社，19856 液压元件与系统（M）北京：机械工业出版社，2005李壮云等编7 行走机械液压传动（M）北京：人民交通出版社，2003姚怀新编8 现代工程机械液压系统分析（M）北京：人民交通出版社，1998颜荣庆编9 孔庆华 刘传绍.极限测量与测试技术基础M.上海：同济大学出版社.200210 实用液压技术（M）北京：机械工业出版社，1999张磊编11理论力学（M）.西北工业大学出版社 2004 尹冠生XXXXXXX毕业设计评阅表学号 XXXXXXX 姓名 XXXXXXX 专业 机械设计制造及其自动化 毕业论文（设计）题目：全液压轮式装载机液压系统的设计直动式溢流阀的设计评价项目评 价 内 容选题1.是否符合培养目标，体现学科、专业特点和教学计划的基本要求，达到综合训练的目的；2.难度、份量是否适当；3.是否与生产、科研、社会等实际相结合。能力1.是否有查阅文献、综合归纳资料的能力；2.是否有综合运用知识的能力；3.是否具备研究方案的设计能力、研究方法和手段的运用能力；4.是否具备一定的外文与计算机应用能力；5.工科是否有经济分析能力。论文（设计）质量1.立论是否正确，论述是否充分，结构是否严谨合理；实验是否正确，设计、计算、分析处理是否科学；技术用语是否准确，符号是否统一，图表图纸是否完备、整洁、正确，引文是否规范；2.文字是否通顺，有无观点提炼，综合概括能力如何；3.有无理论价值或实际应用价值，有无创新之处。综合评 价XXXXXXX同学在毕业设计期间，能努力学习，刻苦钻研，作风踏实，行动积极，面对难题敢于钻研。能认真完成毕业设计任务，论文撰写基本流畅、工作量较饱满、论文格式符合规范，图标较清楚，鉴于其本科毕业设计已达到学士学位论文的要求。 同意其进行毕业论文答辩。 评阅人： 2012年5月 日XXXXXXX毕业论文（设计）鉴定意见 学号：XXXXXXX 姓名： XXXXXXX 专业： 机械设计制造及其自动化 毕业论文（设计说明书） 32 页 图 表 7 张论文（设计）题目：全液压轮式装载机液压系统的设计直动式液流阀的设计 内容提要： 目前国内外的装载机广泛采用液压技术，可使整个装载机的技术经济指标得到提高。装载机主要用于装卸运作业。本设计的主要内容包括：工作装置液压系统、转向机构液压系统和行走机构液压系统的设计计算；标准液压元件的选择计算；液压系统的验算；非标件直动式溢流阀和动臂液压缸的设计计算。行走机构采用脚踏式操纵，先导控制的液控调速方式，使调速换向更为方便；工作装置采用先导控制，使系统操作更加简便；转向机构采用方向盘转向，运用人机学，使驾驶室的布置更为合理，便于操纵。整个系统安全可靠、结构紧凑和维修方便。 指导教师评语XXXXXXX同学在毕业设计期间，态度积极端正，认真查阅了一系列文献资料，做了比较充分的准备工作，在此期间完成了方案的初步设计，方案被认定可行。在此基础上，该同学通过对方案的分析，完成了全液压轮式装载机液压系统的设计，以及液压元件直动式液流阀的设计，并完成了相关的特性分析。利用 CAD软件画出了液压系统的结构图和装配图以及部分零件图。完成了说明书的书写以及相关外文文献的翻译。在设计过程中，XXXXXXX同学认真努力，论文立意正确，论述比较清楚，符合设计要求。同意该同学参加答辩。指导教师： 年 月 日答辩简要情况及评语 答辩小组组长： 年 月 日答辩委员会意见答辩委员会主任： 年 月 日 目录摘要IAbstractII前 言1第一章 全液压轮式装载机液压系统的工作原理21.1设计依据21.1.1全液压轮式装载机液压系统的主要特点21.1.2设计参数21.2全液压轮式装载机液压系统的工作原理31.2.1行走机构液压系统3 1.2.2工作装置液压系统61.2.3转向机构液压系统8第二章 液压系统主要参数的确定102.1行走机构液压系统若干问题102.1.1液压泵参数的确定102.1.2液压马达的参数112.2铰接式车架的计算载荷122.2.1两缸轴线至铰接点中心距离和行程确定122.2.2转向泵流量122.2.3最小转弯半径122.3工作装置液压系统132.3.1活塞直径和活塞杆直径的确定132.3.2液压缸流量的计算132.4原动机功率选择计算142.4.1运输工况功率142.4.2插入工况功率15第三章 非标准液压元件的设计163.1动臂液压缸的设计163.1.1液压缸的设计计算163.1.2液压缸的作用能力、作用时间及储油量的计算173.1.3液压缸壁厚的计算183.1.4活塞杆的计算183.1.5液压缸零件的连接计算203.2直动式溢流阀的设计233.2.1设计要求233.2.2主要结构尺寸的初步确定233.2.3静态特性计算253.2.4弹簧的设计计算26第四章 结束语.30参考文献31附录32 全液压轮式装载机液压系统的设计直动式溢流阀的设计摘要目前国内外的装载机广泛采用液压技术，可使整个装载机的技术经济指标得到提高。装载机主要用于装卸运作业。本设计的主要内容包括：工作装置液压系统、转向机构液压系统和行走机构液压系统的设计计算；标准液压元件的选择计算；液压系统的验算；非标件直动式溢流阀和动臂液压缸的设计计算。行走机构采用脚踏式操纵，先导控制的液控调速方式，使调速换向更为方便；工作装置采用先导控制，使系统操作更加简便；转向机构采用方向盘转向，运用人机学，使驾驶室的布置更为合理，便于操纵。整个系统安全可靠、结构紧凑和维修方便。 AbstractRecently, the loader uses the hydraulic technology widely to make the target of its technological economy improved. The loader is used to do loading and unloading operation. This design includes the following aspects: the calculation of the design of the hydraulic system of equipment, steering gear, and running gear; the calculation of the design of nonstandard direct-acting overflow valve and the moving armed hydraulic cylinder. The running gear uses pedal control and the method of piloted pilot-operated speed governing to make the speed governing and reversing gear done much easier. The equipment uses the indirect control to make system operation much easier. The steering gear uses the changing direction of steering wheel and ergonomics to make the arrangement of the cab more suitable and easier to control. The whole system is more safe and reliable, the structure of which is tighter knit, and it is convenient to maintain.Key words: loader, hydraulic system, hydraulic cylinder, direct-acting overflow valveII 前 言一、研究或设计的目的和意义装载机是一种广泛用于公路、铁路、建筑、水电、港口、矿山等建设工程的土石方施工机械，它主要用于铲装土壤、砂石、石灰、煤炭等散状物料，也可对矿石、硬土等作轻度铲挖作业。该课题结合机械设计专业的教学内容和我省工程机械的应用及发展，对装载机液压系统作较深入的分析研究。根据设计依据及要求，完成装载机液压系统的设计直动式溢流阀的设计，进一步掌握液压系统的设计方法和步骤。通过毕业设计，使我们进一步巩固、加深对所学的基础理论、基本技能和专业知识的掌握，使之系统化、综合化；使我们获得了从事科研工作的初步训练，培养我们的独立工作、独立思考和综合运用已学知识解决实际问题的能力，尤其注重培养我们独立获取新知识的能力；培养我们在设计方案、设计计算、工程绘图、实验方法、数据处理、文件表达、文献查阅、计算机应用、工具书使用等方面的基本工作实践能力；使我们树立具有符合国情和生产实际的正确设计思想和观点，树立严谨、负责、实事求是、刻苦钻研、勇于探索、具有创新意识、善于与他人合作的工作作风。二、研究或设计的国内外现状和发展趋势液压技术式一门先进的技术，特别是计算机技术的发展再次将液压、技术推向前进，发展成为包括传动、控制、检测在内的一门完整的自动化技术。目前国内外的装载机都采用液压技术，可使整个装载机的技术经济指标得到提高，其发展趋势是开发节能、高效、可靠、环保型产品，并研制无泄漏装载机，微电子及机电液一体化技术将获得越来越广泛的应用，安全性及舒适性是产品发展的重要目标， 大型化与微型化仍是产品系列化的两极方向，技术进步、人才培养和售后服务将成为企业生存的三大关键内在因素，集团化、社会化与国际化是企业生存与发展的必由之路。三、主要研究或设计内容，需要解决的关键问题和思路主要设计内容包括：设计5全液压轮式装载机液压系统、直动式溢流阀和动臂液压缸的设计、液压系统的设计计算、标准液压组件的选择计算、液压系统的验算、非标准件的设计计算等。需要解决的关键问题是液压系统无极调速回路及液压系统安全保护回路的设计。可以通过综合应用已学的理论知识解决设计中的问题。 第一章 全液压轮式装载机液压系统的工作原理1.1 设计依据1.1.1 全液压轮式装载机液压系统的主要特点1、设计用于露天作业的前端式装载机的液压系统，该装载机的工作装置、转向机构和行走机构均采用液压传动。2、行走机构能实现无级调速。3、工作装置、转向机构和行走机构，采用单独驱动。4、工作装置为反转连杆式。5、行走机构为轮胎式。6、采用柴油机为动力。7、安全可靠、机构紧凑、维修方便。1.1.2 设计参数1、额定斗容5。2、额定载重量10。3、轴距3.5。4、轮距2.8。5、机重24。6、工作装置（1）、工作压力1014；（2）、转斗缸最大推力22；铲斗卸载时间36；转斗时间25；转斗缸行程520；（3）、动臂缸最大推力20；动臂提升时间25；动臂下降时间36；动臂缸行程560。7、转向机构（1）、工作压力1014；（2）、最大转向阻力矩2100；（3）、最大转向角3040；（4）、铰接两车架从最左到最右偏转角所需时间为36。8、行走机构（1）、工作压力1826；（2）、最大行走速度15；（3）、工作速度34；（4）、最大牵引力30；（5）、轮胎滚动半径680；（6）、最大爬坡能力30。1.2 全液压轮式装载机液压系统的工作原理轮式装载机液压系统包括行走机构液压系统、工作装置液压系统和转向机构液压系统三个部分，见图1.1。1.2.1 行走机构液压系统行走机构液压系统按其作用分为：主回路、补油和热交换回路、调速和换向回路、主泵回零及制动回路、补油回路和压力保护回路。1、主油路由两个独立的闭式回路组成。如图1.2所示，斜轴式轴向柱塞变量泵5高压油口前轮内曲线径向柱塞马达9（后轮内曲线径向柱塞马达10）斜轴式轴向柱塞变量泵5低压油口。图1.2 主油路2、补油和热交换回路（1）、补油回路齿轮泵1分流阀21补油阀6斜轴式轴向柱塞变量泵5的低压侧。（2）、热交换回路前轮内曲线径向柱塞马达9或后轮内曲线径向柱塞马达10排出的部分热油梭阀 变速阀15（为图示位）背压阀26过滤器59油箱61。12调压阀11 前轮内曲线径向柱塞马达9或后轮内曲线径向柱塞马达10的壳体过滤器60油箱61。注意：调压阀22的开启压力调压阀11的开启压力，才能实现正常的热交换。（3）、调速和换向回路a、若脚踏先导阀17上位工作齿轮泵1分流阀21断流阀20（图示位）脚踏先导阀17上位液动阀25下端液动阀25阀芯上移，下位工作。先导泵3液动阀25下位变量液压缸24下腔变量液压缸24活塞杆伸出杠杆机构斜轴式轴向柱塞变量泵5的缸体摆角或斜轴式轴向柱塞变量泵5的流量或。若斜轴式轴向柱塞变量泵5的缸体摆角方向改变，则斜轴式轴向柱塞变量泵5排油方向改变前轮内曲线径向柱塞马达9或后轮内曲线径向柱塞马达10的转向改变实现装载机的前进或后退。 b、若脚踏先导阀18上位工作齿轮泵1分流阀21断流阀20脚踏先导阀18上位液动阀25上端液动阀25阀芯下移，上位工作。先导泵3液动阀25上位变量液压缸24上腔变量液压缸24活塞杆缩回杠杆机构斜轴式轴向柱塞变量泵5的缸体摆角或斜轴式轴向柱塞变量泵5的流量或。若斜轴式轴向柱塞变量泵5的缸体摆角方向改变，则斜轴式轴向柱塞变量泵5排油方向改变前轮内曲线径向柱塞马达9或后轮内曲线径向柱塞马达10的转向改变实现装载机的后退或前进。 高速档（变速阀15图示位）c、通过变速阀15，可得两档车速 低速档（变速阀15左位）（低压控制油作用） 当前轮内曲线径向柱塞马达9或后轮内曲线径向柱塞马达10为高速工况（即变速阀15为图示位） 连通阀16左移，即是图示位工作前后轮的油路连通； 当前轮内曲线径向柱塞马达9或后轮内曲线径向柱塞马达10为高速工况（即变速阀15为左位）连通阀16右移，左位工作前后轮油路不通。（4）、主泵回零及制动回路调速阀27由离心调速器控制，离心调速器与发动机是用带轮连接。离心调速器作用a、若外负载F，超过发动机，发动机转速 调速阀27左移，右位工作（为图示位）；b、液动阀25的控制油交替逆止阀19调速阀27油箱61；c、斜轴式轴向柱塞变量泵5摆角减小直到零位降低泵的输出功率，避免发动机因过载而熄火；图1.1 5立方全液压轮式装载机液压系统图停车时，断流阀20左位工作，则连通脚踏先导阀17和脚踏先导阀18随动阀25上下端控制油与油箱61相通随动阀25回到中位伺服变量机构斜轴式轴向柱塞变量泵5缸体摆角回零，为零前轮内曲线径向柱塞马达9和后轮内曲线径向柱塞马达10制动。（5）、补油回路制动及超速吸空时，低压油补油阀13前轮内曲线径向柱塞马达9和后轮内曲线径向柱塞马达10。（6）、压力保护回路a、主回路高压保护 系统的工作压力过载阀7过载阀7开启溢流。b、低压保护调压阀22控制补油压力。c、油马达背压保护前轮内曲线径向柱塞马达9和后轮内曲线径向柱塞马达10排出的部分热油调压阀14背压阀26过滤器60油箱61当系统长时间不工作时，按下换向阀8将斜轴式轴向柱塞变量泵5吸排油口相通前轮内曲线径向柱塞马达9和后轮内曲线径向柱塞马达10不转动装载机不动。1.2.2 工作装置液压系统1、转斗液压缸52活塞杆伸出（1）、先导油路将转斗先导阀37的手柄向左按下先导泵3单向阀29转斗先导阀37左上位转斗液压缸多路液动换向阀45左端转斗液压缸多路液动换向阀45左位工作。（2）、主油路进油路：工作泵2单向阀46转斗液压缸多路液动换向阀45左腔转斗液压缸52活塞腔转斗液压缸52活塞杆向外伸出。回油路：转斗液压缸52活塞杆腔油转斗液压缸多路液动换向阀45左腔过滤器55油箱61。2、转斗液压缸52活塞杆缩回（1）、先导油路将转斗先导阀37的手柄向右按下先导泵3单向阀29转斗先导阀37右上位转斗液压缸多路液动换向阀45右端转斗液压缸多路液动换向阀45右位工作。（2）、主油路进油路：工作泵2单向阀46转斗液压缸多路液动换向阀45右腔转斗液压缸52活塞杆腔转斗液压缸52活塞杆缩回。回油路：转斗液压缸52活塞腔油转斗液压缸多路液动换向阀45右腔过滤器55油箱61。3、转斗液压缸52补油和过载保护补油：转斗液压缸52活塞腔或活塞杆腔吸空时，通过补油阀48补油。过载保护：转斗液压缸52活塞腔或活塞杆腔过载时，通过过载阀49开启溢流。4、动臂液压缸53举升（1）、先导油路将动臂举升先导阀38的手柄向右按下先导泵3单向阀29动臂举升先导阀38右上位动臂举升多路液动换向阀42左端动臂举升多路液动换向阀42左位工作。（2）、主油路进油路：工作泵2节流阀44单向阀43动臂举升多路液动换向阀42左腔动臂液压缸53活塞腔动臂液压缸53举升。回油路：动臂液压缸53活塞杆腔油动臂举升多路液压换向阀42左腔过滤器55油箱61.5、动臂液压缸53下降（1）、先导油路将动臂举升先导阀38的手柄向左按下，按到左中位先导泵3单向阀29动臂举升先导阀38左中位动臂举升多路液动换向阀42右端动臂举升多路液动换向阀42右位工作。（2）、主回路进油路：工作泵2节流阀44单向阀43动臂举升多路液动换向阀42右腔动臂液压缸53活塞杆腔动臂液压缸53下降。回油路：动臂液压缸53活塞腔油动臂举升多路液动换向阀42右腔过滤器55油箱61。6、动臂液压缸53浮动将动臂举升先导阀38的手柄向左按下，按到左上位先导泵3单向阀29动臂举升先导阀38左上位液控单向阀51液压单向阀51的液压油逆向流动动臂液压缸53的活塞杆腔和活塞腔与油箱61相通，进出油都可以。7、动臂液压缸53补油和过载保护补油：动臂液压缸53活塞腔或活塞杆腔吸空时，通过液控单向阀51补油。过载保护：动臂液压缸53活塞腔或活塞杆腔过载时，通过过载阀50开启溢流。8、其他元件的作用调压阀36的作用是调节减压阀式先导操纵阀的操纵油的压力。背压阀39是使液动换向阀51具有背压。当发动机突然熄火时，动臂液压缸53活塞腔的油通过单向阀41和节流阀40向动臂举升先导阀38和转斗先导阀37紧急供应操纵油。9、工作泵（主泵）2过载保护当转斗液压缸52和动臂液压缸53不工作时，工作泵2油箱61；当转斗液压缸52或动臂液压缸53工作时，系统过载，工作泵2安全阀47油箱61。1.2.3 转向机构液压系统1、直线行驶方向盘不转全液压转向器31处于中位（图示位）液动主控制阀32处于中位（图示位）转向液压缸54没有液压油通过装载机直线行驶。转向泵4定差溢流阀33油箱61。2、右转弯（1）、先导油路顺时针转动方向盘螺杆轴向上移全液压转向器31上移全液压转向器31下位工作。先导泵3全液压转向器31下腔计量马达进口计量马达出口液动主控制阀32左端（液压主控制阀左位工作）液动主控制阀32中的先导阀口液动主控制阀32的右端全液压转向器31下位过滤器55油箱61。（2）、主油路进油路：转向泵4液动主控制阀32左腔转向液压缸54A活塞腔和B活塞杆腔装载机向右转弯。回油路：转向液压缸54A活塞杆腔和B活塞腔油液动主控制阀32左腔过滤器55油箱61。3、左转弯（1）先导油路逆时针转动方向盘螺杆轴向下移全液压转向器31下移全液压转向器31上位工作。先导泵3全液压转向器31上腔计量马达进口计量马达出口液动主控制阀32右端（液压主控制阀右位工作）液动主控制阀32中的先导阀口液动主控制阀32的左端全液压转向器31上位过滤器55油箱61。（2）主油路进油路：转向泵4液动主控制阀32右腔转向液压缸54B活塞腔和A活塞杆腔装载机向左转弯。回油路：转向液压缸54B活塞杆腔和A活塞腔油液动主控制阀32右腔过滤器55油箱61。4、其他液压元件的作用液控主控制换向阀32、定差溢流阀33、安全阀34和梭阀35组成流量放大阀。梭阀35把液动主控制阀32的出口压力引至定差溢流阀33的弹簧腔，液动主控制阀32的进口压力作用定差溢流阀33的另一腔，使得液动主控制阀32进出口压力差基本恒定，转向液压缸54的运动速度进取决于液动主控制阀32的阀口面积。5、过载保护当先导泵工作时过载，先导泵3直动式溢流阀28过滤器56油箱61；当工作装置和转向机构不工作时，先导泵3换向阀8（右位工作）过滤器56油箱61。转向液压缸54的高压油梭阀35安全阀34过滤器55油箱61。 第二章 液压系统主要参数的确定2.1 行走机构液压系统若干问题1、由设计要求知：最大行走速度=15 =（1-） （2-1）式中： 滑转率，=0.030.05 ，取=0.04。则： 理论行驶速度=15.6252、理论行驶速度 =2=0.377 （2-2）式中： 驱动轮的滚动半径（），=0.680；驱动轮转速（）。则： =60.9823、最大行驶速度发生在运输工况：最大牵引力产生在装载机以作业速度插入料堆时。4、进行牵引力和扭矩计算时应考虑驱动轮的数目。2.1.1 液压泵参数的确定 = （2-3）式中： 液压泵的排量（）；液压泵吸排油口压力差（），由设计要求知其工作压力为1826，取=25，其背压为0.5，则=25-0.5=24.5=24.5；液压泵的转速（），取=1000=104.667；最大行驶速度（），=15 =4.167； 液压泵与液压马达的总效率，取=0.8； 行走时的最大牵引力（），=+= + ； 滚动阻力()； 爬坡阻力()，一般小坡度可取=0.3； 滚动阻力系数，取f=0.03； 装载机重量()，G=240000。 则 =39600注：由于系统是四轮驱动，采用的2个泵，所以计算时要除以2。液压马达的变速范围，定量马达=1，若采用变量泵系统，马达的变速范围=1。则： =8.044液压泵的理论流量：=8.044=505.163液压泵的功率：=210.4852.1.2 液压马达的参数液压马达的排量： （2-4）式中： 液压马达的最大转速（），=6.135；液压马达的机械效率，取=0.92；液压马达的进出口压力差（），=25-1=24=24；最大牵引力（），采用的是4马达驱动，则：=19800。则： =6.098其液压马达的理论流量：= =224.211液压马达的扭矩：=198000.680=13464=6.2082.2.1 液压缸流量的计算活塞杆外伸速度：= （2-18）活塞杆缩回速度： （2-19）式中： 缸的容积效率；取=0.851、动臂液压缸：提升时间25，下降时间36，行程=560=70 =14 =112 =11.2即 =1564.458=589.5812、 铲斗液压缸：铲斗卸载时间36，转斗时间25，行程=520=104=10.4=130 =13即 =1500.735=903.4402.3 原动机功率选择计算2.3.1 运输工况功率 （） （2-20）式中： 产生最大速度时的驱动力（），=； 额定牵引力（），=； 机械的附着重量（），四轮驱动为机重，=240000； 额定附着系数，=0.450.55，取=0.5。 滚动阻力，=； 机重（），=240000； 滚动阻力系数，取=0.03。=2400000.5+2400000.03=127200 传动系统的总效率，取=0.8；为转向泵（空载）、工作泵（空载）消耗功率总和。 =12.240 =43.229 =+=12.240+43.229=55.469则 =+55.469=718.022 7182.3.2 插入工况功率 （2-21）式中： 装载机插入时的原动机功率（）；最大插入阻力（），最大牵引力=+=198004=79200 装载机自重（），=240000； 滚动阻力系数，=0.1； 道路坡度，上坡为正，下坡为负，=10；装载机的插入速度，=0.81.1；考虑其他阻力系数，=1.201.25，取=1.225；泵到马达的总效率，取=0.8。则 =79200=52800=80850=80.85 第三章 非标准液压元件的设计3.1 动臂液压缸的设计如图3.1所示，为动臂液压缸。当左端进油时活塞杆伸出，动臂举升；当右端进油时，动臂下降；当两端都与油箱连通时，动臂浮动。图3.1 动臂液压缸3.1.1 液压缸的设计计算1、查表选用双作用单活塞杆液压缸，选用尾部耳环式安装方式；2、由于动臂液压缸采用2个，所以=100000；3、系统的工作压力为1014，取系统的工作压力为12，往复速比=2.21，则取=2，即缸径=100，活塞杆直径=80；4、动臂液压缸的行程为560，速度为：提升时，=7 下降时，=11.2 流量为：提升时，=782.229 下降时，=589.581查表得出供油口的直径：=16。3.1.2 液压缸的作用能力、作用时间及储油量的计算1、如图3.2，当向有杆腔供油时，活塞杆向内收进时的拉力为：图3.2 双作用液压缸 （5-1）式中：活塞杆直径（）； 缸内径（）； 工作压力（）； 液压缸机械效率，一般取=0.95。= =51009.32、液压缸的作用时间（油从活塞腔供入时的情况）： （5-2）式中：缸内径（）；行程（）；流量（）。 =6.869 ；符合条件。3、液压缸的储油量： = （5-3）=5319.16 3.1.3 液压缸壁厚的计算 （5-4）式中：试验压力（），额定压力16， 16，；缸内径（）；缸体材料许用拉应力（）， 采用无缝钢管，=（100110），取=105。则 =0.00943取=0.01=10，=0.091=0.1，为薄壁钢筒。3.1.4 活塞杆的计算1、按强度条件验算活塞杆直径：查表得：=93010=80；当10时的受压柱塞或活塞杆需作压杆稳定性验算（即是纵向弯曲极限力计算）。2、纵向弯曲极限力计算 液压缸受纵向力以后，产生轴线弯曲，当纵向力达到极限力以后，缸产生纵向弯曲，出现不稳定现象。该极限力与缸的安装方式，活塞杆直径及行程有关。 细长时： （5-5） 细长时: （5-6）式中： 活塞杆的计算长度（），查表得：取两端铰接，=930； 活塞杆横截面积回转半径（），=20； 活塞杆横截面积转动惯量（），=2009600； 活塞杆横截面积（），=5024； 柔性系数，对钢取=85； 端盖安装形式系数，查表得：=1； 材料弹性模数（），对钢=206； 材料强度实验值（），对钢490； 系数，对钢取。=46.5，=85，即有： =1718566.0933、纵向弯曲强度验算： （5-7）式中：安全系数，一般取=24，取=3； 活塞杆推力（），=113982。=1139823=341946=1718566.093=341946，符合条件。3.1.5 液压缸零件的连接计算1、缸体和缸底的焊缝强度计算 缸体与缸底用电焊连接时焊缝应力： （5-8）式中：活塞杆推力（），=113982； 焊接效率，可取=0.7；焊条材料的抗拉强度（），其材料和缸体的抗拉强度差不多，取=105。由图3.3知：=110+210=130=110+10=120图3.3 缸体与缸底焊接即有： =82.971=82.971=105符合条件。2、缸体与缸盖用法兰连接的螺栓计算 许用应力： （5-9）式中：螺栓或拉杆的数量，查表得：=12； 螺栓螺纹部分危险剖面计算面积（），查表得：=78.5； 螺纹预紧系数，可取=1.351.6，取=1.4； 液压缸最大推力，=113982；即有： =169.43、活塞与活塞杆半环连接的计算 活塞杆的拉力： （5-10）式中：活塞杆直径（）； 缸内径（）；工作压力（）。即有： =53694活塞杆危险断面处的合成应力（考虑近似等于活塞杆退刀槽处的拉应力）： （5-11）式中：活塞杆拉力（）； 活塞杆危险断面处的直径（），查表得：=49；系数，可取=1.4；许用应力（），活塞杆采用调质强度HB=240270的40钢，=400。即有： =39.883符合条件。4、活塞杆与活塞肩部压应力验算 （5-12）式中： 活塞杆直径（），=0.08； 活塞上的钻孔直径（）， 作用于活塞上的工作压力()； 活塞上钻孔的倒角尺寸()，=0.804； 许用压应力()，活塞材料采用耐磨铸铁（A3），则=160。=63.435符合条件。3.2 直动式溢流阀的设计如图3.4所示为滑阀型直动式溢流阀，压力油从进油口进入阀后，经过阻尼孔作用在阀芯底下，阀芯的底面上受到油压的作用形成一个向上的液压力。当液压力小于弹簧力时，阀芯在调压弹簧的预压缩力作用下处于最下端，由底端螺塞限位，阀处于关闭状态；当液压力等于或大于调压弹簧力时，阀芯向上运动，上移封油长度S后阀口开启，进口压力油经阀口流回油箱，此时阀芯处于受力平衡状态。图3.4 直动式溢流阀3.2.1 设计要求1、额定压力=2.5；2、额定流量为先导泵的出口流量，其=72.5。3.2.2 主要结构尺寸的初步确定1、进出油口直径：按额定流量和允许流速来确定，则：= （5-13）式中： 额定流量()； 允许流速()，一般取=6。即 =0.0160取 =162、阀芯的直径：按经验取 0.92） =（0.50.82）16 =813.12取 =133、阀芯活塞直径：按经验取 =（1.62.3） =（1.62.3）13 =20.829.9取 =30对阀的静态特性影响很大，按上式选取时，对额定流量小的阀选较大的值。4、节流孔直径、长度：按经验取 =0.080.2 =（719）取 =0.2=2=25节流孔的尺寸和对溢流阀性能有重要影响。如果节流孔太大或太短，则节流作用不够，将使阀的启闭特性变差，而且工作中会出现较大的压力振摆；反之，如果节流孔太小或太长，则阀的动作会不稳定，压力超调量也会加大。5、阀芯溢流孔直径和和可根据结构确定，但不要太小，以免产生的压差过大，不利于阀的开启。6、阀体沉割直径、沉割宽度按经验取 =+（0.11.5） =30+（115） =3145 取 =40按结构确定，应保证进出油口直径的要求。7、调压杆的有效长度应保证阀芯的位移要求，即 式中：阀的最大开度，其大小见静态特性计算。8、直动式溢流阀的其他尺寸按结构要求定。3.2.3 静态特性计算静态特性计算主要内容是根据要求的定压精度和卸荷压力确定弹簧及阀口开度等主要参数。1、额定开度计算 （5-14）式中： 额定压力（）； 阀芯直径（）； 油液密度； 阀口流量系数，=0.78。即有 = =0.0005092、按开启比率确定弹簧的预压缩量溢流阀的开启比率： （5-15）故弹簧的预压缩量： （5-16）式中： 阀口处液流的射出角（）， =69； 一般在计算中可取=0.90.95。即有 = =-0.03753、确定弹簧的刚度因 （5-17）故 = =8181.008应该注意，这里的预压缩量是指阀口刚关闭时的数值，故包括了滑阀的封油产度。4、按要求的卸荷压力值，计算滑阀的最大开口量 （5-18）式中： 卸荷压力（），通常取=（0.150.35），取=0.2。即有 = =0.00183.2.4 弹簧的设计计算1、选择材料和许用切应力根据弹簧的工作条件，属类载荷弹簧，选用碳素弹簧钢丝。初步假定钢丝的直径=2.5，中径=16，查表得其抗拉强度=1710。查表得其许用切应力=0.5=0.51710=855。查表得其切变模量=79。2、弹簧钢丝直径由弹簧直径和弹簧中经计算其旋绕比 =6.4查得其曲度系数=1.23。计算材料的直径 （5-19）式中： 弹簧的工作载荷（），=306.788； 许用切应力（）； 曲度系数，=1.23； 旋绕比，=6.4。即有 =2.46根据GB135，取=2.5,与原假设吻合。3、弹簧有效圈数 圈 （5-20）式中： 切变模量（）； 弹簧中径（）； 旋绕比，=6.4； 弹簧刚度（）。则 =11.51圈取有效圈数=11.5圈，取支承圈=2.5圈，则总圈数 =11.5+2.5=14圈弹簧的几何参数总结在表5.1：表3.1 弹簧的几何尺寸名称代号单位计算方法或公式及其结果材料直径2.5弹簧中径16弹簧内径=16-2.5=13.5弹簧外径=16+2.5=18.5有效圈数11.5压缩弹簧的支承圈数2.5总圈数=11.5+2.5=14节距=（0.280.5）=4.488，取=6间距=6-2.5=3.5自有高度=611.5+22.5=74压缩弹簧高径比=4.625螺旋角（）=6.81弹簧材料的展开长度4、压缩弹簧稳定性验算高径比较大的压缩弹簧，轴向载荷达到一定值就会产生侧向弯曲而失去稳定性。为保证稳定性，高径比3.7=4.6255.3，采用两端固定。5、弹簧工作图，如图3.5：图3.5 弹簧工作图 第四章 结束语装载机是一种作业效率高，机动灵活，用途广泛的工程机械，主要用于装卸运作业和地面平整工作。本设计完成了5全液压轮式装载机液压系统的设计直动式溢流阀的设计，主要内容包括：液压系统图的拟定，元件的计算和选择，系统的压力损失计算和温升计算，非标件直动式溢流阀和动臂液压缸的设计计算。首先，行走机构液压系统采用脚踏式操纵、先导控制的液控调速方式，使调速换向更为简便。系统设有补油和热交换回路、主泵回零及制动回路、补油回路和压力保护回路，很好的增加了元件的耐用性。系统采用前后轮驱动，空载行走时，采用前轮驱动：载重行走时，采用前后轮驱动，这样作业效率增加，且节约燃料。由于液压行走系统压力损失和温升很大，所以目前的装载机的行走系统很少采用液压，参考的东西比较少，所以在元件的选择上，具有一定的盲目性。工作装置液压系统采用先导控制，使得整个工作装置操作起来更加简便。系统设有过载保护和吸空补油回路，很好的保护了系统中的各元件。动臂液压缸的控制部分设有浮动位，简化了驾驶员的操作。转向机构液压系统采用方向盘转向，运用人机学，使驾驶室的布置更为合理，便于操纵。当出现突发状况，驾驶员可以抱紧方向盘，更好的保证自己的安全。系统中采用流量放大器，使装载机转向更加灵活、准确。整个系统安全可靠、结构紧凑和维修方便。参考文献1 液压传动与气压传动M。华中科技大学出版社。2008 杨曙东 何存兴主编2 现代工程图学M.湖南科学技术出版社。2000 周良德 杨世平 邱爱红等主编3 机械设计（第八版）M.高等教育出版社北京.2002 纪名刚等主编4 机械原理（第七版）M.西北工业大学机械原理及机械零件教研室.20065 工程机械液压系统设计计算（M）北京：机械工业出版社，19856 液压元件与系统（M）北京：机械工业出版社，2005李壮云等编7 行走机械液压传动（M）北京：人民交通出版社，2003姚怀新编8 现代工程机械液压系统分析（M）北京：人民交通出版社，1998颜荣庆编9 孔庆华 刘传绍.极限测量与测试技术基础M.上海：同济大学出版社.200210 实用液压技术（M）北京：机械工业出版社，1999张磊编11理论力学（M）.西北工业大学出版社 2004 尹冠生附录名称序号图纸张数图幅图号5全液压轮式装载机液压系统11A001-00-00-00动臂液压缸21A101-01-00-00缸头31A301-01-01-00缸筒41A401-01-01-01直动式溢流阀51A101-02-00-00阀芯61A401-02-01-00阀体71A201-02-02-00Hydraulic systemChapter 1 IntroductionHydraulic Pump Station also known as the stations are independent h- ydraulic device. It requested by the oil gradually. And controlling the hydraulic oil flow direction, pressure and flow rate, applied to the mainframe and hy- draulic devices separability of hydraulic machinery. Users will be provided after the purchase hydraulic station and host of implementing agencies (motor oil or fuel tanks) connected with tubing, Hydraulic machinery can be realized from these movements and the work cycle.Hydraulic pump station is installed, Manifold or valve combination, t- anks, a combination of electrical boxes.Functional components : Pump device - is equipped with motors and pumps, hydraulic station is the source of power. to mechanical energy into hydraulic oil pressure can be. Manifold - from hydraulic valve body and channel assembled. Right direction for implementation of hydraulic oil, pressure and flow control. Valve portfolio - plate valve is installed in up board after board conn-ects with the same functional IC. Tank - plate welding semi-closed containers, also loaded with oil filtering network, air filters, used oil, oil filters and cooling. Electrical boxes - at the two patterns. A set of external fuse terminal plate; distribution of a full range of electrical control. Hydraulic Station principle : motor driven pump rotation, which pump oil absorption from the oil tank. to mechanical energy into hydraulic pressure to the station, hydraulic oil through Manifold (or valve combinations) realized the direction, pressure, After adjusting flow pipe and external to the cylinder hydraulic machinery or motor oil, so as to control the direction of the motive fluid transformation force the size and speed the pace of promoting the various acting hydraulic machinery. 1.1 A development course China Hydraulic (including hydraulic, the same below), pneumatic and seals industrial development process can be broadly divided into three phases, namely : 20 early 1950s to the early 1960s, the initial stage; 60s and 70 for specialized production system ;8090s growth stage for the rapid development stage. Which, hydraulic industry in the early 1950s from the machine tool industry production of fake Su-grinder, broaching machine, copying lathe, and other hydraulic drive started, Hydraulic Components from the plant hydraulic machine shop, self-occupied. After entering the 1960s, the application of hydraulic technology from the machine gradually extended to the agricultural machinery and mechanical engineering fields, attached to the original velocity of hydraulic shop some stand out as pieces of hydraulic professional production. To the late 1960s, early 1970s, with the development of mechanized production, especially in the second automobile factory in providing efficient, automated equipment, along with the Hydraulic Components manufacturing has experienced rapid development of the situation, a group of SMEs have become professional hydraulic parts factory. 1968 Chinas annual output of hydraulic components have nearly 200,000 in 1973, machine tools, agricultural machinery, mechanical engineering industries, the production of hydraulic parts factory has been the professional development of more than 100 and an annual output more than one million. an independent hydraulic manufacturing industry has begun to take shape. Then, hydraulic pieces of fake products from the Soviet Union for the introduction of the product development and technical design combining the products to the pressure, Hypertension, and the development of the electro-hydraulic servo valves and systems, hydraulic application areas further expanded. Aerodynamic than the start of the industrial hydraulic years later, in 1967 began to establish professional pneumatic components factory, Pneumatic Components only as commodity production and sales. Sealed with rubber and plastics, mechanical seals and sealing flexible graphite sealing industry, the early 1950s from the production ordinary O-rings. rubber and plastics extrusion, such as oil seal sealing and seal asbestos products start to the early 1960s, begun production of mechanical seals and flexible graphite sealing products. 1970s, the burning of the former Ministry, a Ministry, the Ministry of Agricultural Mechanization System, a group of professional production plants have been established, and the official establishment of industries to seal industrial development has laid the foundation for growth.Since the 1980s, in the countrys reform and opening up policy guidelines, with the development of the machinery industry, based mainframe pieces behind the conflicts have become increasingly prominent and attracted the attention of the relevant departments. To this end, the Ministry of the original one in 1982, formed the basis of common pieces of Industry, will be scattered in the original machine tools, agricultural machinery, mechanical engineering industries centralized hydraulic, pneumatic and seals specialized factories, placing them under common management infrastructure pieces Bureau, so that the industry in the planning, investment, technology and scientific research and development in areas such as infrastructure pieces Bureau of guidance and support. Since then entered a phase of rapid development, has introduced more than 60 items of advanced technology from abroad, including more than 40 items of hydraulic, pneumatic 7. After digestion and absorption and transformation, now have mass production, and industry-leading products. In recent years, the industry increased the technological transformation efforts, in 1991, Local enterprises and the self-financing total input of about 20 billion yuan, of which more than 1.6 billion yuan Hydraulic. Through technological transformation and technology research, and a number of major enterprises to further improve the level of technology, technique and equipment to be greatly improved. In order to form a higher starting point, specialization, and run production has laid a good foundation. In recent years, many countries in the development of common ownership guidelines, under different ownership SMEs rapid rise showing great vitality. With the further opening up, three-funded enterprises rapid development of industry standards for improving and expanding exports play an important role. Today, China has and the United States, Japan, Germany and other countries famous manufacturers joint ventures or wholly-owned by foreign manufacturers to establish a piston pump / motor, planetary reduction gears, steering gear, hydraulic control valve, hydraulic system, hydrostatic transmission, hydraulic Casting. pneumatic control valve, cylinder, gas processing triple pieces, mechanical seals, rubber and seal products more than 50 production enterprises, attracting foreign investment over 200 million U.S. dollars. 1.2 the current situation 1.21Basic Profiles After 40 years of efforts, China hydraulic, pneumatic and sealing industry has formed a relatively complete categories. a certain level of technical capacity and the industrial system. According to the 1995 Third National Industrial Census statistics, hydraulic, Pneumatic seals and industrial 370,000 annual sales income of 100 million yuan in state-owned, village-run, private and cooperative enterprises, individual, three capital enterprises with a total of more than 1,300, of which about 700 hydraulic, Pneumatic seals and the approximately 300 thousand. By 1996 with the international trade statistics, the total output value of Chinas industry hydraulic 2.348 billion yuan, accounting for the worlds 6; Pneumatic industry output 419 million yuan, accounting for world No. 10. 1.22 the current supply and demand profiles Through the introduction of technology, independent development and technological innovation, and high-pressure piston pump, gear pumps, vane pump, General Motors hydraulic valves, tanks, Non-lubricated aerodynamic pieces and various seals of the first large technology products has increased noticeably. stability of the mass production may, for various mainframe products provide a level of assurance. In addition, hydraulic and pneumatic components of the CAD system, pollution control, proportional servo technology has scored some achievements, and is already in production. Currently, hydraulic, pneumatic and seals products total about 3,000 species, more than 23,000 specifications. Among them, there are 1,200 hydraulic varieties, more than 10,000 specifications (including hydraulic products 60 varieties 500 specifications); Pneumatic are 1,350 varieties, more than 8,000 specifications; Rubber seal 350 species more than 5,000 specifications have been basically cater to the different types of mainframe products to the general needs, complete sets of equipment for major varieties of matching rate was over 60%, and started a small amount of exports. 1998 pieces of homemade hydraulic output 4.8 million. sales of about 28 billion (of which about 70% mechanical systems); aerodynamic pieces yield 3.6 million. sales of about 5.5 billion (of which about 60% of mechanical systems); Seals output of about 800 million. sales of about 10 billion (of which about 50% mechanical systems). According to the China Hydraulic Pneumatic Seals Industry Association 1998 annual report, hydraulic product sales rate of 97. 5% (101% for hydraulic), pneumatic 95.9%, 98.7% sealed. This fully reflects the basic marketing convergence.My hydraulic, pneumatic and sealing industry has attained a great deal of progress, but with mainframe development needs, and the worlds advanced level, there are still many gaps, mainly reflected in the product variety, performance and reliability, and so on. Hydraulic products as an example, products abroad only one-third, life for half abroad. In order to meet key mainframe, and mainframe imports of major technology and equipment needs, every year a large number of hydraulic, pneumatic and sealing products imports. According to customs statistics and the analysis of data, in 1998 hydraulic, pneumatic and seals in the import about 200 million U.S. dollars, Hydraulic which about 1.4 billion dollars, aerodynamic nearly 030 million U.S. dollars, sealed about 030 million U.S. dollars. compared with a slight decline in 1997. By sums, currently imported products on the domestic market share of about 30%. 1998 pieces of the domestic market demand for hydraulic total of about six million, the total sales of nearly 40 billion; aerodynamic pieces of the total demand of about 5 million, with sales more than 700 million yuan; Seals total demand of about 1.1 billion. total sales of about 1.3 billion. 1.3 the development trend of the future 1.31 affect the development of the main factors (1) product development ability, and the level of technological development and speed can not completely meet the advanced mainframe products, major equipment and technology imported equipment and maintenance support; (2) the number of enterprises manufacturing technology, the level of equipment and management standards are comparatively backward, coupled with a strong sense of quality, resulting in low levels of product performance, quality, Reliability poor services in a timely manner, lack of user satisfaction and trust of the brand-name products;(3) industry specialization of production low, scattered strength, low repeat serious, between regions and enterprises of convergence products, blindly compete with each other, driving down prices, the decline of enterprise returns, lack of funds, liquidity difficulties, product development and technological transformation is inadequate and seriously restricted the industry to improve the overall level of competition and the increase of strength; (4) The internationalization of the domestic market and the increasing degree of foreign companies have entered the Chinese market and participate in competition with the domestic private and cooperative enterprises, individuals, foreign-funded enterprises, such as the rise of state-owned enterprises due to the growing impact. 1.32 the development trend As the socialist market economy continues to deepen, hydraulic, pneumatic and sealing products in the market supply and demand and there is a greater change, long ago to a shortage of the sellers market has basically become a structural surplus of the characteristics of the buyers market place . Overall capacity, is already in oversupply situation, in particular the general low level of hydraulic, pneumatic and seals, the general oversupply; and the host of urgent high-tech high-parameter, high value-added high-end products, and they do not satisfy the market needs, only dependent on imports. China joins the WTO, its impact may be even greater. Therefore, the 15 during the growth of the output value of industry, must not depend on volume growth and the industry should address the structural problems of their own, increase the intensity of the adjustment of the industrial structure and product mix, is, we should rely on the improvement of quality, and promote technical upgrading of products to meet market demand and stimulating, seek greater development.2 The application of hydraulic power sliding stage2.1 Power sliding Taiwan introducedThis paper deals with the investigation for slide units impact and motion stability in modular machine tool fay means of the method of power bond graph and state space analysis. The dynamic mathematical model of self-adjusting back pressure speed control system used to drive slide unit is established. Main reasons and affecting factors for slide unit impact and motion unstability are analysed through computer digital simulation, It is concluded from those that, if the structural dimensions of hydraulic cylinder and back pressure valve are designed rationally, the slide units dynamics will markedly be improved.NOMENCLATURESfflow sourceSeisliding friction force in slide unitRequivalent viscous friction coefficient in slide unitIimass of slide unit and cylinderhmass of SABP valve spoolCi,C2hydraulic capacitances of rod chamber and non-rod chamber in cylinder re-spec-tivelyC3spring compliance of SABP valveRrR2hydraulic resistances of damping holesR9hydraulic resistance of orifice of SABP valveSe2presetting force of spring in SABP valveI4J5equivalent liquid inertia in pipe linesCCgequivalent hydraulic capacitances in pipe lines equivalent hydraulic resistances in pipe linesV-j Voil-containing volumes in non-rod chamber and rod chamber respectivelyP,r:, P-ioil pressures in non-rod chamber and rod chamber respectivelyFload acted on slide unitVslide unit velocity* Department of Mechanical Engineering, Dalian Ur.iversity of Technology, Dalian. China.2.2 IntroductionDuring operation of modular machine tool, the changes of slid units speed and load acted on it in both magnitude and direction will affect working performar.ee to a different extent Particularly the impact caused by sudden vanishing of load and the motion unstability due to periodical change of load in operation will affect the surface quality of the workpiece machined, and the tool would be broken off under serious conditions, By using the method of power bond graph and state space analysis, the dynamic mathematical model of the system used to drive slide unit is established, that is called as self-adjusting back pressure speed control system and abbreviated to SABP system. In order to improve slide units dynamics, it is necessary to find out the main reasons and affecting factors, that must be based on computer digital simulation and study on the results.2.3 Dynamic Mathematica ModeldThe schematic diagram of SABP system is shown in Fig.l, the system is used to perform the cycle of feeding, stopping and returning. Four way control valve works in the right position during slide units feeding. The supply pressure of the pump is approximately constant under the action of pressure relief valve, the oil through the control valve and pressure compensated flow control valve enters the non-rod chamber to put slide unit forward. At the same time, the oil from the rod chamber is discharged through SABP valve and directional control valve to tank. In this process, the state of two check valves and pressure relief valve is not changed, To establish the mathematical model as reasonably and simply as possible, consideration must be focused on main affecting factors for a complex non-linear system such as the SABP system. It is illustrated by theoretical analysis and test result , that the transient time of the system is much longer than that of the flow control valve, and the flowrate overshoot of the valve in transients affects very small to slide unit speed because of the ;large effective sectional area of non-rod chamber in cylinder. For investigating the systems dynamics widely and deeply, the initial modeltn is further simplified in this paper, and so the study can be efficiently made with microcomputer. It is assumed that the flowrate through the flow control valve isconstant in the whole transient process, and is denoted to a flow source.Fig.2 shows the structure diagram of the dynamic model of the system, it is composed of cylinder, slide unit, SABP valve and pipe line; etc.By using the method of power bond graph and state space analysis in this paper, the dynamic mathematical model of the system is to be established- The power bond graph is a power flow diagram, which expresses abstractly the actions among sub-systems as three effects, i.e. resistance effect, capacitive effect and inertia effect, according to the way of energy transform, on the basis of practical structure and by means of method of lumped parameters. The model is characterized by a clear conception in physics, and non-linear system can be accurately analysed in combination with method of state space analysis, thus it is a effective method used in the dynamic investigation of complex non-linear system in thetimedomain.From main performances of components in SAEP system, the power bond graph of the system has been formed by means of the rule of model establishing and is shown in Fig.3. Half arrow in each bond indicates a direction of power How, two variahles of power are effort variable and flow variable. O-junction illustrates algebraic summation of flow variables at common effort, i.e. parallel connection, 1-junction does algebraic summation of effort variables at common flow, i.e. series connection. The symbol TF represents power transformer between two types of energy, and transforming modulus between efforts or flows is noted below the symbol TF. Short transverse bar across one end of each bond shows causality between two variables. A full arrow expresses a control action. Among three actions, there is an integration or differential form in capacitive effect and inertia effect between two variables. So state equation may be derived from Fig.3, there are nine state variables in this complex nonlinear equation. Studying on the slide units dynamics is started with impact and motion stability. The equation is simulated by using the method of 4th order Runge-Kutta integration procedure on IBM-PC computer. Fig.4 and Fig.5 illustrate the results respectively.Slide units impact phenominon results from loads vanishing in the transients, for example, the situation of drilling through workpiece, Fig.4 expounds the variations of the load and speed of slide unit, the pressures of chambers in cylinder. When slide unit motions evenly under the action of load, the oil pressure in non-rod chamber is very high, and there is a lot of hydraulic energy accumulated in side. The pressure decreases at once with loads discharging rapidly. During the process of oil pressure converting from high to low, the system absorbs some of the energy, so slide unit impacts forward with high speed. And then the oil in rod chamber iscompressed to increase back pressure, some of the energy is consumed, which plays a part of restraining the impact of the slide unit. It must be noted that inlet pressure of SABP valve telys on the interaction of pressures of two chambers, and increases rapidly at the instant of loads vanishing, and then stabilizes at some value greater than initial one. This pressure is also greater than one of traditional speed control system, therefore the energy can be absorbed much more in the rod chamber. In result, the impact of slide unit in SABP system is 20% lawer than in traditionals. It is thus clear that slide unit with SABP system for driving has a good performance in restraining the impact and SABP valve plays an important part in that,2.4 Motion stabilityWhen load acting on slide unit varies periodically, such as the situation of milling, slide units speed will bring about some pulse. In order to meet the requirements of manufacturing quality, the magnitude of the speed pulse must be reduced as small as possible. The variation of the load is assumed to be of sine wave, in order to simplify discussion of the problem, The result of digital simulation is shown in Fig.5 It can be seen that, the response of the system is the sameas traditionls and the differences between them are very small. The reason for this is that the variation of the load is not targe, there the pressures in chambers vary very little that is, the effect of the SABP valve is not obvious.2.5 ImprovementIt is shown by studying, that dynamics of slide unit which used SABP speed control system as driving system is better than that of traditional system. To reduce the slide units impact, the back pressure of rod chamber has to be increased rapidly in the transients of loads vanishing; on the other hand, to enhance the slide units motion stability, it is necessary to raise the system rigidity. However, main recommendation lies in decreasing the volume of oil. It is known from system structure that, there is a lot of oil-containing volume between the rod chamber and drain pipe as shown in Fig.6a. Because the volume exists, not only the effect of SABP valve is delayed and reduced, hut also the rigidity of the system is decreased. Therefore, it is hindered to further improve the impact and motion stability. To make the slide unit dynamics better, the structural dimensions of cylinders chamber and the SABP valve must be designed suitably. Based on simulations under the various structural dimensions and comparison among the results, the following two measures can be taken for improvements:The ratio between volumeV4 and V3 is changed from 5.5 to 1 approximately, as shown in Fig,6b;8the bottom diameter of spool of the SABP valve is increased from 10 mm to 13 mm and the length of side of triangular damping slot is decreased from 1 mm to 0.7mm the slide unites impact quantity can be reduced by 30%, and the time of dynamic response is shortened. In addition, slide units motion stability may be improved obviously. It is thus evident that improvements are very effective.液压系统1绪论液压站又称液压泵站，是独立的液压装置。它按逐级要求供油。并控制液压油流的方向、压力和流量，适用于主机与液压装置可分离的各种液压机械上。用户购后只要将液压站与主机上的执行机构（油缸或油马达）用油管相连，液压机械即可实现各种规定的动作和工作循环。液压站是由泵装置、集成块或阀组合、油箱、电气盒组合而成。各部件功能为：泵装置上装有电机和油泵，是液压站的动力源，将机械能转化为液压油的压力能。集成块由液压阀及通道体组装而成。对液压油实行方向、压力和流量调节。阀组合板式阀装在立板上，板后管连接，与集成块功能相同。油箱板焊的半封闭容器，上还装有滤油网、空气滤清器等，用来储油、油的冷却及过滤。电气盒分两种型式。一种设置外接引线的端子板；一种配置了全套控制电器。液压站的工作原理：电机带动油泵转动，泵从油箱中吸油供油，将机械能转化为液压站的压力能，液压油通过集成块（或阀组合）实现了方向、压力、流量调节后经外接管路并至液压机械的油缸或油马达中，从而控制液动机方向的变换、力量的大小及速度的快慢，推动各种液压机械做功。1.1发展历程 我国液压（含液力，下同）、气动和密封件工业发展历程，大致可分为三个阶段，即：20世纪50年代初到60年代初为起步阶段；6070年代为专业化生产体系成长阶段；8090年代为快速发展阶段。其中，液压工业于50年代初从机床行业生产仿苏的磨床、拉床、仿形车床等液压传动起步，液压元件由机床厂的液压车间生产，自产自用。进入60年代后，液压技术的应用从机床逐渐推广到农业机械和工程机械等领域，原来附属于主机厂的液压车间有的独立出来，成为液压件专业生产厂。到了60年代末、70年代初，随着生产机械化的发展，特别是在为第二汽车制造厂等提供高效、自动化设备的带动下，液压元件制造业出现了迅速发展的局面，一批中小企业也成为液压件专业制造厂。1968年中国液压元件年产量已接近20万件；1973年在机床、农机、工程机械等行业，生产液压件的专业厂已发展到100余家，年产量超过100万件，一个独立的液压件制造业已初步形成。这时，液压件产品已从仿苏产品发展为引进技术与自行设计相结合的产品，压力向中、高压发展，并开发了电液伺服阀及系统，液压应用领域进一步扩大。气动工业的起步比液压稍晚几年，到1967年开始建立气动元件专业厂，气动元件才作为商品生产和销售。含橡塑密封、机械密封和柔性石墨密封的密封件工业，50年代初从生产普通O型圈、油封等挤压橡塑密封和石棉密封制品起步，到60年代初，开始研制生产机械密封和柔性石墨密封等制品。70年代，在原燃化部、一机部、农机部所属系统内，一批专业生产厂相继成立，并正式形成行业，为密封件工业的发展成长奠定了基础。 进入80年代，在国家改革开放的方针指引下，随着机械工业的发展，基础件滞后于主机的矛盾日益突出，并引起各有关部门的重视。为此，原一机部于1982年组建了通用基础件工业局，将原有分散在机床、农业机械、工程机械等行业归口的液压、气动和密封件专业厂，统一划归通用基础件局管理，从而使该行业在规划、投资、引进技术和科研开发等方面得到基础件局的指导和支持。从此进入了快速发展期，先后引进了60余项国外先进技术，其中液压40余项、气动7项，经消化吸收和技术改造，现均已批量生产，并成为行业的主导产品。近年来，行业加大了技术改造力度，19911998年国家、地方和企业自筹资金总投入共约20多亿元，其中液压16亿多元。经过技术改造和技术攻关，一批主要企业技术水平进一步提高，工艺装备得到很大改善，为形成高起点、专业化、批量生产打下了良好基础。近几年，在国家多种所有制共同发展的方针指引下，不同所有制的中小企业迅猛崛起，呈现出勃勃生机。随着国家进一步开放，三资企业迅速发展，对提高行业水平和扩大出口起着重要作用。目前我国已和美国、日本、德国等国著名厂商合资或由外国厂商独资建立了柱塞泵/马达、行星减速机、转向器、液压控制阀、液压系统、静液压传动装置、液压件铸造、气动控制阀、气缸、气源处理三联件、机械密封、橡塑密封等类产品生产企业50多家，引进外资2亿多美元。 1.2目前状况 1.21基本概况 经过40多年的努力，我国液压、气动和密封件行业已形成了一个门类比较齐全，有一定生产能力和技术水平的工业体系。据1995年全国第三次工业普查统计，我国液压、气动和密封件工业乡及乡以上年销售收入在100万元以上的国营、村办、私营、合作经营、个体、“三资”等企业共有1300余家，其中液压约700家，气动和密封件各约300余家。按1