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汽车起重机液压系统外文翻译
汽车式起重机液压系统 ―技术现状与发展趋势一、行业背景 （一）国外工程汽车起重机的发展趋势 近 20 年世界工程起重机行业发生了很大变化。 RT(越野轮胎起重机)和 AT(全 地面起重机)产品的迅速发展，打破了原有产品与市场格局，在经济发展及市场 激烈竞争冲击下，导致世界市场进一步趋向一体化。为与 RT 和 AT 产品抗衡，汽 车起重机新技术、新产品也在不断发展。近年来汽车起重机在英、美等国市场的 复兴，使人们对汽车起重机产生新的认识。几年前某些工业界人士曾预测，RT 和 AT 产品的兴起将导致汽车起重机的衰退。日本汽车起重机在世界各地日益流 行，以及最近格鲁夫、特雷克斯、林克．贝尔特、德马泰克等公司汽车起重机的 产品进展， 已向上述观念提出挑战。随着工程起重机各机种间技术的相互渗透与 竞争，汽车起重机会在世界市场中继续占有一席之地。 国外工程起重机从整体情况分析， 领先国内 10～20 年(不同类型产品有所不 同)。随着国外经济发展速度趋于平稳，工程起重机向智能、高性能、灵活、适 应性强、多功能方向发展。25t 以下基本上不生产，产品向高附加值、大吨位发 展，住友建机、多田野和加藤公司曾于 1989 年相继推出 360t 汽车起重机。住友 建机在 90 年代开发出 80t～250t 共 4 种 AT 产品。多田野也在 90 年代相继推出 100t～550t 共 6 种特大型 AT 产品。加藤公司则研制成 NK5000 型 500t 汽车起重 机。行业配套也与国内有所不同： 1、下车主要是 300kW 以上柴油大功率发动机，与之配套的液力变矩器和自 动换档变速箱、12 吨级驱动转向桥及越野轮胎。 2、上车：高强度材料、大扭矩的起升机构、回转机构、回转支承。 3、液压系统：变量泵、变量马达、电磁换向先导阀及主阀、平衡阀、悬挂 系统阀、液压锁、液压缸及管路标准配套件。 4、智能控制系统：力限器显示控制、记忆通讯及单缸顺序伸缩自动控制。 （二）国内工程汽车起重机的发展趋势 国内工程机械产品近十年来随着技术的引进、消化、吸收，有了长足的进步， 产品性能、可靠性、外观都有较大幅度的提高，但同国外工程机械比较来看，还 存在较大差距。 国内工程起重机行业在 94～99 年是发展低谷，5 年中行业几个主要的生产厂 家，苦练内功，积极组织产品变型和换代，在产品外观上下功夫。从 99 年以来， 随经济建设新一轮启动， 工程起重机市场竞争格局发生巨大变化，各企业不断调 整思路、更新观念、转换机制、提高核心竞争力，努力开发产品，开拓市场。产 品重心也从 8t、12t 向 16t、25t、50t 中大吨位发展，25t 增速最快，产量不断 翻新，基本占据主导地位。50t 产品由于需求面较广，技术逐渐成熟，也大批量 进入市场。 世纪末期国内主要产品系列汽车起重机为 8t、 20 12t、 16t、 20t、 25t、 35t、50t、65t、80t、l00t、125t。整体技术风格是：下车有全头和半头两种不同风格， 多年来半头车因总体布置的方便性及价格 因素一直被广泛采用。 但近年来随着物质条件的改善，人们的生活条件和质量提 高， 操作方便、 舒适、 可靠逐渐成为用户关注的焦点， 中大吨位向全头方向发展。 上车操纵从传统的机械操作向液比例和电液比例方向发展， 起重吊臂也从传 统的三节向四节、五节方向发展，产品的起重性能和起重高度有了较大提高，产 品的外观和可靠性有了较大幅度提高。 加入世贸组织后， 虽然国内市场(特别是配套件)受到了较大冲击，但同时也 给我们带来新技术的应用， 使国内主机和配套件企业更清晰认识到差距，更多地 了解国产产品存在的致命问题， 迫使国产主机和配套件企业不得不进行技术创新 和技术进步。 经过几年的努力，国内起重机厂家取得了巨大进步。被誉为神州第一吊的 QY300轮式液压汽车起重机2004年在中联浦沅成功下线。它代表了中国汽车起重 机制造的最高水平． 填补了我国自主研制生产该类产品的空白，打破了此类产品 完全依赖进口的惯例。缩短了我国起重机行业与国外的差距，但差距还很大，很 多厂家主要还是靠购买国外的“落后”技术，缺乏自主研发能力。这让国人感到 担忧。二、国内外汽车起重机液压系统新技术（一）关于汽车起重机液压系统安全问题的诸多研究 1. 代智能超载限制器在汽车起重机中的运用 第三代微电脑超载限制器(XT一Ⅲ 型)，是具有自主知识产权的国产机电一 体化装置。该装置由主机部分和传感器部分组成，微电脑控制，模块化结构。安 装调试全部采用按键操作、 大屏幕液晶点阵显示， 在参数设置及显示上非常简明， 不用调整任何电位器，使调试变得简单直观，界面友好。限制器采用了数字和大 规模集成电路，减少了故障，增加了抗干扰能力，从而提高了可靠性；当起重机 超过额定起重量或超行程时，能自动报警并切断起重机向危险方向运动的回路， 但允许其向安全方向动作；系统故障自动检测，结果显示；低功耗(整机功耗小 于10W)，数字电路全部采用CMOS芯片；黑匣子功能，自动记录超载时间及当时的 各工况参数；数据及参数显示全部图形汉字提示，数值准确，直观方便，操作人 员一目了然，无需操作人员熟记提示符；密码设定功能，防止参数误设定；通用 性好，在不改变主机的情况下，只要修改软件，就能够满足各种类型重机机械的 要求；机内存储了多组额定载荷曲线，满足了各种工况无级报警要求；对传感器 的“温度漂移”和“零点漂移”可进行自动调节补偿；具有声光报警功能。该技 术现已被国内很多起重机厂家用于大型起重机上面，效果良好。 2. 重机负荷传感系统分析 负荷传感系统可分为两大类：泵控负荷传感系统和阀控负荷传感系统，前者 必须采用变量泵，后者可用于定量泵。目前我国所引进的日本、德国技术常用的 是阀控负荷传感系统。阀控负荷传感系统的原理： 阀控负荷传感系统是由泵、负荷传感控制阀(压力补偿阀)和可变节流口(换向阀 阀口)等组成。泵提供的工作油液流经可变节流口后，形成负载压力作用于执行 机构。 负荷传感控制阀接受负载压力传感信号，通过压力补偿作用保持可变节流 口两端压差基本不变，并使系统压力仅高于负载压力一个压差。这样，既使得流 过节流口的流量仅与节流口开度面积成正比而与负载大小无关， 保证了执行机构运动速度良好的调节性和稳定性；又减少了系统激流的压力损失，提高了系统效 率。 负荷传感控制阀作为负荷传感系统的核心元件，有多种结构类型。在加藤、 多田野和利勃海尔汽车起重机阀控负荷传感系统中，采用了定差胜流阀式、优先 分流阀式及其组合形式。图1负荷传感控制阀压力补偿作用原理图1为定差溢流阀和优先分流阀的压力补偿作用原理图。如图中所示，当可 变节流口(换向阀阀口)FC处于某一开度位置， 定差溢流阀及RC或优先分流阀PF 达到平衡状态时， FC两端压差△Pt(Po―Pr或P1―Pr)对阀芯所产生的液压作用力 与阀芯左端弹簧力将保持平衡。来自泵的工作油液(Po)一部分直接或经阀口h1 去FC支路， 另一部分剩余油液经阀口h2去油箱或旁通支路(Pz)。若FC支路负载压 力Pr随执行机构负载增加(减小)时，阀芯右移(左移)，减小(增大)阀口h2和增大 (减小)阀口h1， 结果系统压力Po和优先支路压力Pl增加(减小)，于是阀芯重新平 蘅在一个新的阀口位置处。 由于弹簧设计得较弱，且阀芯平衡位置变化的位移量 很小， 因此弹鳖力的变化可以忽略不计，从而保证与弹簧力相平衡的换向阀节流 口FC两端压差将基本上保持不变。同时，系统压力仅略高于负载压力。对定差溢 流阀而言， 系统压力Po高于负载压力Pr一个定值，即由弹簧设定的换向阀节流口 两端压差△Pt对优先分流阀而言，优先支路压力P1=Pr+△Pt;系统压力Po则略高 于支路压力P1与P2中的大者。 3. 重机的拘停保护 起重机电动机的控制接触器常常是密集通断的，因此易发生触头熔焊故障。 当起重机在运行过程中需要准确定位或紧急停止时， 如果因触头熔焊导致起重机 拒停，就有可能发生碰撞事故。为解决这个问题，提出一个起重机升降机构拒停 保护设计。 从三个方面着手解决这个问题，其一是接触器触头熔焊导致其动作不合逻 辑，这可增加一个中间继电器来判断；其二是为避免接触器、继电器动作竞争导 致保护误起动，为此拒停保护设置短暂延时，即需要一个时间继电器；第三是一 旦接触器拒跳时，由总断路器分励脱扣动作执行保护。 从电气角度看， 防止起重机拒停的关键措施是监视制动器接触器触头是否熔 焊。图2是QRIS型升降机构控制柜采用拒停保护的设计电路图。 这个设计电路由三个环节构成。第一个是监视环节，由与制动器接触器K07 线圈并联的中间继电器构成，K07与K1 正常情况下是同步动作的。如果K7因触头 熔焊不能释放，那么两者动作就不一致，这就将起动延时环节。 第二环节， 即延时环节是借用原设计中的K03时间继电器，由并联的K7 常闭 接点和K07常开接点控制。K7、K07 并联接点在正常情况下总是接通的，只有在 停止时K7触头发生熔焊的情况下并联接点才断开。 K03时间继电器通电立即吸合， 断电延时释放，延时0.6s，因此只要控制电路一得电，K03立即吸合。而且主令 控制器S40 。在起动、停止的切换过程中，即使K7、K07 接点动作竞争，瞬时断 开 线圈回路，K03延时闭合的常闭接点仍保持断开，因此K7、K07 并联接点接入 K03线圈回路不会影响K03 的正常工作。 在未接入并联接点前， 只有在主令控制器转到上升2挡或下降3挡后，因加速 级接触器K42得电，K42常闭接点断开，K03才断电释放，其常闭接点延时闭合， 使加速级接触器K41能够吸合， 切除第3级起动电阻。在主令控制下降2挡一0挡一 上升1挡之间切换时，由于主令控制器17、18和19、20接点均是断开的，加速级 接触器K42不能吸合，K03不可能断电，此时常闭接点也不起作用，即K03在升降机构起动和停止阶段实际上是不工作的。 而拒停保护正是工作在起重机停止和起 动阶段，因此可以在K03不工作的时间将其借来为拒停保护工作，为此，在K03 线圈回路中插入并联接点。 一旦因K7触头熔焊导致起重机拒停，并联接点立即断 开，K03继电器断电，其常闭接点经0．6s延时后闭合，接通总断路器Q0的分励脱 扣线圈YA―OFF，使总断路器跳闸，升降机构制动器断电制动，达到拒停保护的 目的。 第三个环节是拒停保护起动环节，它由K03延时闭合的常闭接点、K7常开接 点、K07常闭接点与总断路器分励脱扣线圈串联而成。总断路器刚合闸的瞬间， K07的常闭接点尚未断开，为此必须在串联电路中接入K7常开接点，否则将导致 分励脱扣线圈得电，使总断路器刚合闸就立即跳闸。K07常闭接点的作用是防止 K03在执行原设计的功能，即延时切除第3级起动电阻时，导致总断路器误跳闸。 因为在起重机加速阶段，K07常闭接点是断开的，因此分励脱扣线圈不会因K03 常闭接点闭合而得电，导致误跳闸。 如果起重机起动前制动接触器K7触头已经熔焊， 那么一合上总断路器Q0由于 并联接点断开， 使K03处于断电状态， K03常闭接点闭合， 而此时K7常开接点、 K07 常闭接点均闭合，这样分励脱扣线圈得电，使刚合上的总断路器立即跳闸，阻止 起重机在不能制动的状态下起动，消除了事故隐患。 为检修安全，将原设计中升降机构控制电源的转换开关Q3由二极改为四极， 这样Q3断开时， 就切断了升降控制电路与总断路器分励脱扣电路的连接，确保升 降控制电路完全断电。Q3可以选用HZ5―10型四极组合开关。 因利用了原设计中的时间继电器， 起重机升降机构的拒停保护只需要增加一 个中间继电器，并将一个二极组合开关改为四极组合开关，所需费用不大。 (二) 起重机电子控制技术 为了提高工程起重机作业效率、减轻劳动强度、防止事故、保障人身和设备 安全，采用了多种多样的控制装置。操纵与控制已成为起重机的重要问题。 要解决操纵与控制问题， 仅靠机械和液压是很不够的，因为操纵与控制实际 上是信息处理问题。机械和液压信息处理能力低，控制性能差，必须引进信息处 理能力强、 控制性能良好的电子技术。现就当前工程起重机上采用得电子控制装 置作一一概述。 1. 载荷力矩限制 为了防止由于过大的载荷所引起的倾翻和折臂等事故， 在工程起重机上设置 了载荷力矩限制器。 微机控制力矩限制器的工作原理如如 3 所示。它是由吊臂角度，长度，起重 量，支腿跨矩等检测装置，微机控制装置，显示，报警及执行机构组成。 其基本工作原理是，由检测装置通过传感器将吊臂的长度，角度，支腿跨矩 等信号，送如微机控制装置。微机控制装置计算出在当前的情况下，起重机允许 起吊的最大重量， 与传感器测出的起重机实际起吊重量进行比较，如果实际起吊 重量达到允许起吊重量的 90%，则微机系统通过显示器和蜂音器发出预报警，提 醒操作人员小心操作。当比值达到 100%时，微机系统通过显示器和蜂音器指示 作业人员停止当前作业并通过执行机构限制起重机只能进行安全方向操作， 停止 一切危险方向的操作。图 3 微机控制力矩限制器原理简图2. 反力感知系统起重作业时， 作业人员用眼睛往往不能正确估计吊重的重量，特别目前采用 先导液压操纵，减轻了操纵力在操纵时荷重的变化，载荷的起吊下落等情况，司 机没有手感，在进行建筑构件吊装和机器设备安装时感到操纵困难。为此，在有 些起重机采用了电子感知系统。 装置了反力感知系统后， 由于有负荷力反馈，司机在操纵杆上可感知吊重的 大小，有助于高精度微动操纵。同时可避免由于起吊过猛，吊重摆动等原因引起 的人身和设备事故。 基本工作原理是检出卷扬马达的压力，通过控制器发出控制电信号，控制电 液比例阀产生相应的液压，作用于反力活塞上，使操纵杆上产生负荷反力感觉。 反力感知系统可以通过反力设定装置， 根据司机的个人特点和作业类型来设 定反力的大小，当认为不需要时，还可以将反力感知系统解除。 3. 防碰撞控制 工程起重机在狭窄的场地工作时，需要控制其作业范围，即限制起重机的旋 转及度及动臂伸缩和变幅范围。 常采用示教再先方式来进行控制，先由操作人员按允许工作范围操作一遍， 由危机系统记下其轨迹， 通过此方式设定作业范围。也可用超声波障碍物检测装 置来实现房碰撞控制。 为了防止碰撞高压线， 引起触电事故和造成供电故障，采用接近高压线自动 报警装置， 检测装置一般采用球形电极，通过静电感应，检测电网的电声强度，然后将 微弱信号经前置放大后， 通过灵敏度装换处理得出与电网的距离，再与控制基准 比较，输出相应的控制信号。 4. 吊重控制装置 在高层建筑和高架道路的建设工程中，为了提高作业效率，缩短工期，使操 作简便和提高安全性，常采用以下吊重控制装置――自动水平移动控制装置。 在起重作业中往往需要吊重作水平移动，通常是靠司机操作技术来实现的， 司机目视吊重的高度，同时操纵变幅和起升两个手柄，又要观察注意周围情况， 操作难度相当大。采用自动水平移动控制装置，只需操纵动臂变幅一个操纵杆， 就能平稳、迅速作高精度的水平移动。 自动水平移动控制装置的组成所示。由传感器，操纵装置控制微机和电液变 换执行装置等组成。传感器包括：角度检测器检出住臂或副臂的角度；旋转编码 器检测住卷筒或副卷筒的转动量； 压力检测器检出住臂变幅操纵阀的先导操纵压 力，作为前反馈输入控制微机；发动机转速传感器检出发动机转速，根据发动机 转速来改变系统的增益。 由主臂角度可算出主臂上支点的高度，为保持吊重水平 移动可算出起升卷筒所需的转动量，来控制卷筒的转动，与旋转编码器测得的卷 筒实际转动量作比较进行修正。压力前反馈和根据发动机转速来改变曾益的目 的，是为了得到高精度平稳的水平移动。此装置采用手动优先原则，主要起升卷 筒一操纵，就自动地从自动切换至手动，当突然遇到障碍物时可避开。图 9 自动水平移动控制装置组成另外为了防止起吊时侧位，产生吊重摇摆而引起翻车、碰撞和折臂等事故，采用吊重中心追随控制机构，如图 10a 所示，只要按一下卷筒操纵杆的按钮，就 能实现吊重中心自动追随。还有旋转急停和旋转缓停转换控制装置。图 10 吊重中心追随和旋转控制机构5. 多路信号传送装置 在单司机室的越野起重机上，一个技术上困难问题是如何在有相对运动的上 下之间传递大量的操纵控制信息（多达几十个） 。驾驶室在上车，而发动机，变 速器，转向，制动和支腿等在下车，如何操纵和来控制它们，解决的办法是尽量 将液压控制信号改为电控制信号，同时为了减少通路，希望一条通路传递多路信 号，这就需要利用微机电子技术。 除了上述介绍的电子控制装置以外，还有许多控制装置。 在发动机， 泵和阀的控制方面：需要适应负载变化和多个液压作动器同时动 作复合操作时的功率控制，实现高载低速和减轻高速，与发动机功率相匹配，充 分发挥发动机功率； 微机操作时发动机和泵的控制，与负载无关和同时动作十相 互无干扰，仅取决于手柄操纵的速度控制，以改善其操纵性能；带负载感应补偿 的节能控制，降低燃 料消耗量。目前这些 方面还大量采用液压控制， 可以预计不久将来将被控制性能优越的电子控制所取 代。另外。这些控制系统目前大多是发动机，泵和阀分开单独控制，今后预计将 实现联合控制。 在全路面起重机和越野起重机上， 目前已有不少采用了微机控制自动换档变 速器。 另外，还有电子监视和故障自动诊断装置等。总之，可以说操纵与控制，起 重机内的信息处理已成为当前起重机进一步发展的焦点。 虽然目前电子控制尚存 在不少为体， 例如传感器技术和电液转换技术收纳感不够成熟，微机控制系统的 抗干扰，包括电磁辐射干扰，温度，湿度，振动和冲击等引起的环境干扰，确实 电子控制的可能性尚存一定问题，但是电子控制是不抗拒的技术潮流，机电信一 体化是工程机械产品更新换代的必然发展方向。 三、展望未来 目前起重机的控制系统主要是机械液压控制，随着电液比例控制技术和电子 技术在控制系统中的比重越来越大以及它的优越性，电液控制将是主要发展潮 流。 随着液压元件、 微机技术和信息技术的不断发展， 智能液压起重机即将出现。 那时这种“巨人”可以替代人们做更多的繁重工作，为人类的发展起到无法估计 的作用。Truck crane hydraulic system Technical status and development trend ofOne, industry background( a ) the development trend of foreign engineering truck crane The past 20 years the world's construction crane industry produced very big change. RT ( cross-country wheel crane ) and AT ( all terrain crane ) the rapid development of product, broke original products and the pattern of the market, in the economic development and the fierce competition in the market impact, leading to world market further towards integration. As with RT and AT counter products, automobile crane new technology, new products are also constantly developing. In recent years auto crane in Britain, the United States market revival, enabling people to generate new understanding of automobile crane. A few years ago, some industry had predicted, the RT and AT product rise will lead to automobile crane recession. Japan automobile crane is increasingly prevalent throughout the world, and more recently, grove, Terex, Linc. Belt, Tokuma Yasuke and other companies automobile crane product development, has the idea to challenge. With all types of engineering crane technology mutual infiltration and competition, automobile lifting the opportunity to continue to occupy a space for one person in the world market. Foreign crane from the overall situation, the leading domestic 10～ 20 years ( different types of different products ). Along with the economic development speed smoothly, construction crane to the intelligent, high-performance, flexible, adaptable, multi-functional direction. The following 25t basically is production, products to the high value added, large tonnage, Sumitomo Construction machinery, the Tadahino and Kato company in 1989 has introduced 360t truck crane. Sumitomo Construction Machinery in the 90's the development of 80t～ 250t total of 4 kinds of AT products. TADANO also in 90 time in succession to launch 100t～ 550t total of 6 kinds of large AT product. Kato company developed NK5000 type 500t truck crane. Supporting industries and domestic different: 1, get off the main diesel engine power is more than 300kW, and the matching of torque converter and automatic gearbox, 12 tons of drive steering bridge and off-road tires. In 2,: high strength material, large torque of the lifting mechanism, a rotating mechanism, slewing bearing. 3, hydraulic system: variable pump, a variable motor, an electromagnetic reversing valve and main valve, balance valve, suspension system, hydraulic lock valve, hydraulic cylinder and standard pipe fittings. 4, intelligent control system: limiter display control, memory communication and single cylinder sequential telescopic automatic control. ( two) the development trend of domestic engineering truck crane Domestic engineering machinery products for nearly ten years with the technology introduction, digestion, absorption, had great progress, product performance, reliability, appearance has greatly improved, but compared with the foreign engineering machinery, still put in bigger difference. China engineering crane industry in 94 ～99 years is the development of the trough, 5 years in the industry several major manufacturers, bitter Liannei Gong, active organization variant andreplacement, in product appearance. From 99 years since, with economy construction is new round started, construction crane market competition pattern produces tremendous change, the enterprise constantly adjust train of thought, newer idea, changeover mechanism, enhance core competitiveness, product development efforts, to develop the market. Product focus from 8t to 16t, 12t, 25t, 50t 25t large tonnage development, the fastest growth rate, yield is renovated ceaselessly, basic dominant. 50t products due to the requirement of wide, technology mature gradually, also enter the market in large quantities. The end of the twentieth Century domestic main products automobile crane for the 8t, 12t, 16t, 20t, 25t, 35t, 50t, 65t, 80t, l00t, 125t. The overall style is: Get off with the head and half head two different styles, for many years a half head car because of overall layout of convenience and price factors have been widely adopted. But in recent years with the improvement of material conditions, people's living conditions and quality improvement, convenient operation, comfortable, reliable users gradually become a focus, large and medium tonnage to the head direction. The car is manipulated from the traditional mechanical operation to the hydraulic and electro-hydraulic proportional direction, lifting arm from the traditional three section to the four section, five section of the direction of development, product lifting performance and lifting height has been greatly improved, product appearance and reliability are greatly improved. After joining WTO, while the domestic market ( especially with Kit ) got bigger impact, but also bring us new technology applications, so that domestic host and supporting enterprise more clearly recognize the gap, to learn more about the domestic products are fatal problems, forcing domestic host and supporting enterprises to carry on technological innovation and technical progress. After several years of efforts, the domestic crane manufacturers have made great progress. Known as China the first hanging QY300 wheeled hydraulic truck cranes Puyuan success off the assembly line in 2004 in. It represents the Chinese automobile crane manufacturing at the highest level. To fill China's independent research and production of the product blank, broke this kind of product entirely dependent on imports of the convention. China's crane industry to shorten the gap with foreign countries, but the gap is still very great, a lot of manufacturers mainly rely on the purchase of foreign &backward & technology, lack of independent research and development ability. It makes people feel worried. Two, domestic and foreign automobile crane hydraulic system new technology ( a ) on truck crane hydraulic system security problems research The 1 generation of intelligent overload limiter of crane in automobile application The third generation of microcomputer overload limiter ( XTⅢ with independent intellectual ), property rights of domestic electromechanical integration device. The device is composed of a main machine part and a sensor part, microcomputer control, modular structure. Installation and commissioning of all the key operation, large screen LCD dot matrix display, in the setting of parameters and the display is very concise, do not adjust any potentiometer, the debugging is simple and intuitive, friendly interface. Limiter adopts digital and large scale integrated circuit, reducing the failure, increases the capacity of resisting disturbance, thereby i when the crane is more than the rated capacity or stroke, can automatically alarm and cut off the crane to the dangerous movement of the loop, but allows it to move towa system of automatic fault detection, low power ( power consumption less than 10W), digital circuit using all the CMOS a black box function, automatic recording overloadtime and then the op data and parameters of all Chinese characters display graphics presentation, numerical accuracy, convenient operation, stick out a mile, no operator is required to memorize setting function, prevent par good generality, without altering the host circumstances, as long as the software changes, can meet various type machine memory a plurality of rated load curve, satisfy various working cont the sensor & drift & and & drift & can carry out automatic regulation and compensation with sound and light alarm function. The technique has been used in many domestic manufacturers of large crane crane above, good results. 2 heavy machine load sensing system analysis Load sensing system can be divided into two categories: pump control load sensing system and valve control load sensing system, the former must use of variable pump, the latter can be used for quantitative pump. At present our country by the introduction of Japan, Germany technology used is the valve load sensing system. Valve load sensing system principle: Valve load sensing system is composed of a pump, load sensing control valve ( valve ) and settable orifice ( valve port of the valve ). Pump to provide the oil flowing through the settable orifice, to form the load pressure is applied to the actuator. Load sensing control valve for receiving a load pressure sensor signal, through the pressure compensation function of settable orifice pressure difference between the ends basically unchanged, and the system pressure just above the load pressure of a pressure differential. Thus, both the flow through the orifice flow only with the throttle opening is proportional to the area and are independent of load, guarantees the implementation of mechanism motion speed regulatio and reduce the system stream pressure loss, improves the efficiency of the system. Load sensing control valve as the load sensing system core components, has many kinds of structure types. In Kato, Tadahino and Liebherr crane control valve load sensing system, employs a constant difference wins flow valve type, the priority valve type and its combination form. Fig 1 load sensing control valve pressure compensation principle The constant difference overflow valve and the priority valve pressure compensation principle diagram. As shown in the picture, when settable orifice ( valve valve ) FC in an open position, the constant difference overflow valve and RC or the priority valve PF balance, FC pressure difference between the ends of△ Pt ( Po, Pr or P1 - Pr ) on the valve plug produced by the hydraulic force and valve spring force will keep balance. From the pump working fluid ( Po ) part directly or through the valve port H1 to FC branch, another part of the remaining oil through the valve port H2 to tank or by-pass ( Pz ). If the FC branch load pressure of Pr with the actuator load increases ( decreases ), the valve core is shifted to the right ( left ), decrease (increase ) the valve opening H2 and increase (decrease) the valve opening H1, the results of system pressure Po and preferred branch pressure Pl increases ( decreases ), then the valve core to balance in a new valve export position. Because the spring design is weaker, and the valve core balance position displacement amount is very small, thus playing the turtle force changes are negligible, thus ensuring and spring force balance valve throttle pressure difference across the FC will basically remain unchanged. At the same time, the system pressure is only slightly higher than the load pressure. On the constant difference overflow valve, pressure Po above the load pressure Pr a constant value, namely the spring set valve throttle pressure difference between the ends of the priority valve of △ Pt,△ Pt priority branch pressure P1=Pr+; Po system pressure slightly higher than the pressure of P1 and P2 branch of the larger.3 heavy machine limited stop protection Crane motor control contactors are often dense on-off, therefore prone to breakdown. When the crane is in the process of operation required for accurate localization or emergency stop, because if the contact welding leads the crane refused to stop, there may be a collision accident. In order to solve this problem, propose a crane lifting mechanism refused to stop protection design. From three aspects to solve this problem, it is a contactor contact welding leads to the action logic, which can increase a m second is to avoid the contactor, relay competition leads to protection false start, therefore refused to stop protection setting short delay, which r third is once contactor refused to jump, by the general circuit breaker shunt tripping action execution protection. From the perspective of crane electrical, prevent to stop are key measures to monitor whether the brake contactor contact welding. QRIS type lifting mechanism control cabinet adopts non stop protection circuit diagram design. The design of circuit is composed of three parts. The first is to monitor, made with brake contactor K07 coil is connected in parallel with the intermediate relay, K07 and K1 under normal circumstances is the synchronization action. If the K7 due to contact welding cannot release, so both movement is inconsistent, it will start delay time link. Second links, namely time delay is borrowed from the original design in the K03 time relay, consists of parallel K7 normally closed contact and a normally open contact of the control K07. K7, K07 parallel contact under normal conditions is always connected, stopping only when the K7 contact occurs when welding condition and connection to disconnect. K03 time relay is energized immediately attracted, power-off time delay time delay release, 0.6s, so long as the control circuit on electric, K03 immediately. And the main controller S40. At the start, stop switch process, even though the K7, K07 contact action of competition, instantaneous disconnection coil circuit, K03 time delay closing of the normally closed contact remained disconnected, so K7, K07 parallel contact access K03 coil loop does not influence the normal work of K03. In an access of parallel contacts before, only in the main controller to rise or fall 3 Block 2 block, due to acceleration level contactor K42 electric, K42 normally closed contacts open, K03 power release, the normally closed contact of the time delay closing, accelerating stage contactor K41 can attract, resection of third level dynamic resistance. In the master control down 2 blocks a block 0, a rise of 1 block when switching between the master controller, 17, 18 and 19, 20 contacts are disconnected, accelerating stage contactor K42 cannot attract, K03 may not power off, the normally closed contact also does not work, namely K03 in lifting mechanism for starting and stopping phase is actually not working. And refused to stop protection is working in crane stopping and starting stage, so can be used in K03 does not work all the time be borrowed for refusing to stop protection work, therefore, in the K03 loop of the coil is inserted in the parallel contacts. Once the K7 contact welding leads the crane refused to stop, parallel contact immediately disconnect, the K03 relay is de-energized, the normally closed contact of the 0.6s delay after the closure, connect to the main circuit breaker Q0 shunt trip coil YA - OFF, bringing the total tripping the circuit breaker, lift brake power-off brake, achieve the purpose of non stop protection. The third link is non stop protection starting point, which consists of a K03 time delay closing of the normally closed contact of the normally open contact, K7, K07 normally closed contact with the total circuit breaker shunt trip coil connected in series. Main breaker just closingmoment, K07 normally closed contact has not yet been disconnected, so we must in the series circuit access K7 normally open contact, otherwise it will cause shunt trip coil gets electricity, making the total circuit breaker tripping just closing immediately. K07 normally closed contact role is to prevent the K03 in the execution of the original design features, i.e. delayed resection third starting resistance, resulting in a total circuit breaker tripping. Because of the crane is accelerated stage, K07 normally closed contact is disconnected, so the shunt trip coil K03 will normally closed contacts closed and electricity, resulting in incorrect trip. If the crane braking contactor before starting K7 contact is welded, so a total circuit breaker Q0 because the shunt contact is opened, so that the K03 is in an off state, K03 normally closed contacts closed, normally open contact, while the K7 K07 normally-closed contacts are closed, so the shunt trip coil gets electricity, so just close general circuit breaker tripping prevent crane in immediately, not braking condition start, eliminate accident hidden danger. For the maintenance of safety, the original design of lifting mechanism control power conversion switch Q3 by diode instead of quadrupole, so Q3 disconnected, cut off the lifting control circuit and circuit breaker shunt tripping circuit connection, ensure the lifting control circuit power. Q3 can use HZ5 - 10 type quadrupole combined switch. By the use of the original design of the time relay, crane lifting mechanism of non stop protection only needs to add an intermediate relay, and a diode switch to quadruple combination switch, costs less. ( two) crane electronic control technology In order to improve the construction crane operation efficiency, reduce labor intensity, prevent accidents, ensure the personal and equipment safety, using a variety of control device. Manipulation and control has become the important problem of crane. To solve the problem by manipulation and control, machinery and hydraulic pressure is not enough, because the steering and control is actually the problem of information processing. Mechanical and hydraulic information processing capacity is low, the control performance is poor, must introduce information processing capability, good control performance of the electronic technology. The current engineering crane electronic control device used for one one overview. 1 load torque limit In order to prevent the excessive loads caused by the tilting and the folding arm and other accidents, the construction crane is arranged on the load moment limiter. Microcomputer control of torque limiter principle as shown on the 3. It is composed of a suspension arm angle, length, weight, leg span detection device, microcomputer control device, display, alarm and executive mechanism. The basic working principle, composed of a detection device by a sensor arm length, angle, legs cross torque signal, sent as a microcomputer control device. Microcomputer control device calculates in the current circumstances, the maximum weight allowed hoisting crane, and the crane hoisting weight sensor detects the actual comparison, if the actual lifting weight to allow lifting weights 90%, then the computer system by a display and a buzzer sends out the alarm, to remind operators of careful operation. When the ratio reached 100%, a microcomputer system by a display and a buzzer to instruct operators to stop the current task and by performing a mechanism to restrict the crane only safe operation direction, stop all the dangerous operation. Fig 3 Schematic diagram of microcomputer control torque limiter The 2 force sensing systemHoisting operation, operation personnel eyes often can not be correctly estimated lifting weight, especially the pilot hydraulic control, reduces the operating force in operation when load changes, load lifting falling situation, drivers do not feel, in building structure hoisting and installation of machinery equipment was operating difficulties. Therefore, in some crane adopts electronic sensing system. Device a force sensing system, due to a negative force feedback, the driver on the control lever can be perceived hanging weight size, contribute to the high precision micro manipulation. At the same time can be avoided due to excessive lifting, hoisting swing and other causes of person and equipment accident. The basic principle is to detect the hoisting motor pressure, through the controller sends the control signals, to control the electro-hydraulic proportional valve to produce the corresponding hydraulic, acting on the reverse force on the piston, allowing manipulation of rod produces the load force feeling. The force sensing system can be achieved by reverse power setting device, according to a driver's personal characteristics and job types to set the counter force, when think that do not need, also can be opposite force sensing system for lifting. 3 anti collision control Construction crane in narrow site work, need to control its operation range, namely limit crane rotation and degree and a movable arm telescopic and variable range. Often used to teach again means to control, the operating personnel according to the allowable working range operation again, the crisis system down its trajectory, the way of setting the scope of work. Also available ultrasonic obstacle detection device to realize real collision control. In order to prevent collision high-pressure line, cause electric shock caused by accidents and power supply failure, with close to the high voltage line automatic alarm device, Detection device usually adopts spherical electrode, through electrostatic induction, detection grid acoustic intensity, then the weak signal preamplifier, through the sensitivity equipment for processing and gets the power distance, and the control baseline comparison, the output of the corresponding control signal. 4 lifting control device In high-rise building and the viaduct 's construction, in order to improve the working efficiency, shorten time limit for a project, so that the operation is simple and improves the safety, often using the following lifting control device of automatic level -- mobile control device. In the lifting operation is often required in every level of mobile crane, usually by the driver operating the technology, driver visual hoisting height, while manipulating the amplitude and lifting the two handles, and observed around, operation difficulty is quite big. Automatic level control device using mobile, simply manipulation of luffing jib of a joystick, can be stable, rapid high precision horizontal movement. Automatic level control device consisting of the mobile. Composed of sensors, control device and control microcomputer electro-hydraulic conversion execution device. The sensor includes : a detection arm angle detec rotary encoder testing live drum or side dr pressure detector detection for arm control valve pilot control pressure, as a feedback input c engine speed sensor detection engine speed, according to the engine speed to vary the gain of the system. From the main arm angle can be calculated on the main arm pivot point height, in order to maintain the level of mobile crane hoisting drum cancalculate the required amount of rotation, to control the rotation of a spool, and a rotary encoder is measured by the actual amount of rotation reel comparison is made with modified. Pressure feedback and according to the engine speed to change had beneficial purposes, in order to get a high accuracy stable level mobile. The device adopts manual priority principle, main hoisting drum manipulation, automatically switching from automatic to manual, when suddenly encountered an obstacle avoiding. Figure 9 automatic horizontal movement control device. In addition to prevent lifting of side, produces a lifting swing caused by collision and rollover, arm folding and other accidents, the hoisting center follow control mechanism, as shown in Figure 10a, just click reel joystick button, can achieve hoisting center automatic following. There are rotating emergency-stopping and rotary suspension conversion control device. Fig 10 hoisting center follow and rotation control mechanism 5 multiplex signal transmission device In the single cab off-road crane, a technically difficult problems is how the relative motion between upper and lower transmitting large amount of control information ( up to several dozen ). Cab in the car, and the engine, transmission, steering, braking and leg in the car, how to manipulate and to control them, the solution is to try to hydraulic control signal to electrical control signals, at the same time in order to reduce pathways, a pathway that transfer the multiplex signal, this would require the use of computer and electronic technology. In addition to the introduction of the electronic control device, and many control device. In the engine, pump and valve control : the need for adaptation to load changes and multiple hydraulic actuators which act at the same time composite operation of the power control, achieve high loading speed and reduce the speed, and engine power match, give full play microcomputer operation when the engine and pump control, and is independent of the load and at the same time act ten no mutual interference, depends only on the handle to control speed control, to improve load sensing compensation energy saving control, reducing the fuel consumption. Currently these also uses lots of hydraulic control, can be expected in the future will be excellent control performance of electronic control is replaced by. In addition. These control systems are mostly engine, pump and valve controlled separately, the future is expected to achieve joint control. In all terrain crane and cross-country crane, many using the computer controlled automatic transmission. In addition, there are electronic surveillance and automatic fault diagnosis device. In short, can be said to manipulate and control, crane within the information processing has become the focus of further development of crane. Although there are still a lot of electronic control for the body, for example, the sensor technology and the electrohydraulic conversion technology storage are not mature enough, microcomputer control system, including electromagnetic radiation interference, temperature, humidity, vibration and impact caused by environmental interference, do electronic control probability of surviving a certain problem, but electronic control is not resist technology trends, machine integrated telecommunication engineering machinery product upgrading of the inevitable development direction. Three, look to the future The crane control system is mainly mechanical hydraulic control, with electro hydraulic proportional control technology and electronic technology in the control system of theincreasingly large and its superiority, electro-hydraulic control will be the main development trend. With the hydraulic components, computer technology and the continuous development of information technology, intelligent hydraulic crane coming. Then the & giants & can replace people to do more work, for human development to estimate the role.}