【正文】 ntire platform will have a maximum load. Hydraulic lifting platform synchronized variety of mechanical structure, a fourwheel mobile lifting platform, elevating platform vehiclemounted, fixed landing platform, sets of cylindertype lift platform, fourcolumn lifting platform, the twocolumn lifting platform, scissor Lifting platform, and other mechanical structure, and mechanical structure of different ways to achieve different movements to meet the different, specific ways of working and working environment. The design of synchronous hydraulic lifting platform is designed to meet the car repair industry in the use of lifting platform. Maintenance workers to consider maintenance when the car convenient and fortable, you need to lift the car a certain height, but such use conditions, most of the requirements of hydraulic lifting platform is fixed, so the fixed hydraulic lift platform. While the four cylinder design can be fixed in the foundation, and to consider their own characteristics and the hydraulic cylinder the height, you can dig a pit in the maintenance shop type of foundation, the four cylinder bolts to fully firmly fixed to the ground by on. In order to be able to check and repair chassis, hydraulic lifting platform not designed for the whole plate fixed on the hydraulic cylinder in the bottom four shelves, is thoughtful, I designed the mechanical structure to meet the fourwheel placed in the middle hollow of the platform structure, so that not only meet the maintenance requirements, but also save a portion of material, making the structure more simple and beautiful. Taking into account the car body as a whole if there is a need to use floating platform from the condition, for example, remove the wheels need repair or need to dress up tires, etc., are required to meet all hold up the whole body, this, this design in each set of two plates of another set of lifting devices, lifting devices to facilitate use of the vehicle chassis will hold up, to achieve overall body vacant. To consider the overall open on the car platform, hold up the car fixed and plate lifting devices, and can be used scissor lift to reach the level of a structure. The biggest advantage of using this structure is not hold up in the chassis to the plate when retracted within this structure, so that the overall structure is beautiful and practical. To meet the car on the platform do not slip and stable place on the platform, placed on the plate antislip skid plate. Programmable Logic Controller (PLC) is an industrial control puter, is the succession of puter, automatic control technology and munication technology as one of the new automatic device. It has strong antiinterference ability, low price, reliability, programming is simple, easy to use and so on, in the industrial field operators by the likes of engineering, so PLC in all areas of industrial control is widely used. The design is based on the ratio of the hydraulic cylinder piston rod valve position control system, namely the use of PLC control signal generated by electrohydraulic proportional valve driver to control the exact location of the hydraulic cylinder. Hydraulic cylinder piston rod displacement sensor displacement feedback signal output by the A / D converted into digital signals into the puter, the PLC signals within a given parison, and the control algorithm according to the set after the output control signal, after D / A converted to analog voltage or current signal proportional electrohydraulic control valve spool position to control the flow of the hydraulic cylinder transmission, drive hydraulic cylinder, to achieve the position of the piston with a load control system as a whole constitute a closedloop control for precise positioning . 原 文 摘 要 液壓升降平臺是一種多功能起重升降設(shè)備，廣泛應(yīng)用于工廠、碼頭、建筑、交通、體育館、設(shè)備檢修等高空作業(yè)及維修。 隨著維修行業(yè)的不斷擴(kuò)大 ，以及自動化水平的進(jìn)一步發(fā)展，為減輕維修人員的勞動強(qiáng)度，使得方便維修，并且能夠更好的提高汽車維修的工作效率，以及汽車維修的服務(wù)質(zhì)量，所以對液壓升降平臺的自動化要求也在不斷提高。為了避免以上缺點(diǎn)，要求更加精確地保證液壓升降平臺的同步升降精度，現(xiàn)在大多數(shù)液壓同步升降平臺逐步淘汰了各種傳統(tǒng)的液壓閥，采用更為精確控制的新型電 液伺服閥、電液比例閥以及電液數(shù)字閥等來控制液壓系統(tǒng)，實(shí)現(xiàn)同步精度高。 液壓升降平臺的系統(tǒng)，要求能夠?qū)崿F(xiàn)四輪汽車在受控高度升降范圍內(nèi)同步升降，安全可靠地控制實(shí)現(xiàn)兩前輪、兩后輪、兩左輪、兩右輪的同步升降，并保證同步升降的精度。電 液比例閥是由比例電磁鐵取代普通液壓閥的調(diào)節(jié)和控制裝置而構(gòu)成的，它可以按給定的輸入電壓或電流信號連續(xù)地按比例、遠(yuǎn)距離地控制流體的方向、壓力和流量。為了更好的響應(yīng)節(jié)能問題，可以在必要的情況使用蓄能器來代替電機(jī)驅(qū)動泵所提供的壓力，直接使用蓄能器來提供壓力滿足液壓缸的相關(guān)運(yùn)動。分流集流閥主要應(yīng)用于液壓雙缸及多缸同步控制系統(tǒng)中。 此次設(shè)計(jì)的液壓升降同步平臺是為滿足在轎車維修行業(yè)中所使用的升降平臺。 可編程控制器（ PLC）是一種工業(yè)控制計(jì)算機(jī)，是繼承計(jì)算機(jī)、自動控制技術(shù)和通信技術(shù)為一體的新型自動裝置。 本設(shè)計(jì)是基于比例換向閥的液壓缸活塞桿位置控制系統(tǒng)，即利用 PLC 產(chǎn)生的控制信號驅(qū)動電液比例閥來控制液壓缸的準(zhǔn)確定位。設(shè)計(jì)將四個液壓缸同時可以固定在地基上，為考慮液壓缸的本身特性和升降高度，可以在維修車間挖一個坑 式的地基，將四個液壓缸充分牢固的通過地腳螺栓固定在地基上。在液壓系統(tǒng)中，油液的清潔度 對液壓系統(tǒng)的正常運(yùn)行有著至關(guān)重要的作用，所以在泵的出油口和油箱的回油口都安裝了過濾器，以此來保證油液的清潔度，這是液壓系統(tǒng)回路中不可缺少的附件。為了使液壓系統(tǒng)中滿足提供安全壓力，不致由于壓力突然變高而對整個液壓系統(tǒng)造成不利影響甚至損壞某些液壓元件，所以采用溢流閥來用作安全閥防止液壓系統(tǒng)過載的保護(hù)。常用的比例閥可分為：比例壓力閥、比例流量閥和比例方向閥三種。為滿足液壓升降平臺的系統(tǒng)設(shè)計(jì)要求，實(shí)現(xiàn)平穩(wěn)的同步升降，以及設(shè)計(jì)所要達(dá)到的功能要求，擬定該系統(tǒng)采用液壓系統(tǒng)的閉環(huán)控制，用來滿足液壓系統(tǒng)的同步精度和控制要求，用以實(shí)現(xiàn)使四輪汽車在受控高度升降范圍內(nèi)同步升降，安全可靠地控制實(shí)現(xiàn)兩前輪、兩后輪、兩左輪、兩右輪的同步升降，并保證同步升降的精度。 在我國，雖然對這種液壓升降同步平臺的研制、生產(chǎn)起步較晚，但是隨著我國經(jīng)濟(jì)的快速發(fā)展，為了適應(yīng)我國在各領(lǐng)域所使用的液壓升降同步平臺發(fā)展的需求，走規(guī)?；?biāo)準(zhǔn)化、集約化、產(chǎn)品配套化、實(shí)現(xiàn)機(jī)、電、液一體化技術(shù)在升降同步平臺上的應(yīng)用。為了避免以上缺點(diǎn)，要求更加精確地保證液壓升降平臺的同步升降精度，現(xiàn)在大多數(shù)液壓同步升降平臺逐步淘汰了各種傳統(tǒng)的液壓閥，采用更為精確控制的新型電液伺服閥、電 液比例閥以及電液數(shù)字閥