液压起重机过载保护系统的设计
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摘要
采用凸轮和杠杆机构作为控制装置,以完全机械—液压方式,不需电的转换,研究设计了一种液压起重机角反馈自动调压系统。系统利用凸轮机构作为吊臂角位移信号输入和转换的环节,将输入量吊臂变幅角度α转换为与之相对应的系统压力p1所要求的先导式溢流阀导阀调压弹簧的预压缩量Xt2。采用杠杆机构作为比例环节以实现线位移的放大以及相互作用力的匹配,从而控制Xt2以实现吊机系统压力p1随吊臂变幅角度α的自动连续调节。系统的核心部分是一个专用先导式溢流阀,它起到根据控制信号调节系统压力p1的作用,实现机—液的转换。先导式溢流阀采用差压式结构,提高了其在低压范围的调压稳定性,并可获得较好的启闭性能,从而实现了用1根调压弹簧在吊机工作压力3~17 MPa(本例)范围内进行连续调压。液压起重机角反馈自动调压系统设计的关键在于通过理论计算预先确定先导式溢流阀调定压力p1与先导阀调压弹簧预压缩量Xt2的函数关系,作为控制系统设计的基础。实验结果表明,采用液压起重机角反馈自动调压系统可以较好地解决液压起重机施工过程可能出现的过载问题。
An angle feedback pressure self-regulating system was studied and designed in a complete mechanical and hydraulic way without electric converting.A cam mechanism was used to input and convert the signal of the crane-arm's angle changing.The input signal,i.e.the radius-changing angle α of the crane arm is converted into the length reduction X_(t2) of the pilot relief valve's pressure regulating spring by the cam mechanism,which corresponds with the pressure p_1 of the crane's hydraulic system.The lever is designed as a proportional and amplifying part in order to coordinate the transmitted force and control the length reduction X_(t2) and then accordingly control the pressure p_1 continuously.The pilot valve's type is in the difference-pressure form.It can improve the pressure regulating stability in the lower pressure range and realize the function of regulating the pressure of the hydraulic system at the range from 3 MPa to 17 MPa only with the same one spring of the pilot valve.To get the analytic function formula about the two variables,i.e.the regulated pressure p_1 and the length reduction X_(t2) in advance is the most important step in design.The results show that the angle feedback pressure self-regulating system for hydraulic crane can effectively solve the problem of angle feedback pressur self-regulating of hydraulic cranes.
An angle feedback pressure self-regulating system was studied and designed in a complete mechanical and hydraulic way without electric converting.A cam mechanism was used to input and convert the signal of the crane-arm's angle changing.The input signal,i.e.the radius-changing angle α of the crane arm is converted into the length reduction X_(t2) of the pilot relief valve's pressure regulating spring by the cam mechanism,which corresponds with the pressure p_1 of the crane's hydraulic system.The lever is designed as a proportional and amplifying part in order to coordinate the transmitted force and control the length reduction X_(t2) and then accordingly control the pressure p_1 continuously.The pilot valve's type is in the difference-pressure form.It can improve the pressure regulating stability in the lower pressure range and realize the function of regulating the pressure of the hydraulic system at the range from 3 MPa to 17 MPa only with the same one spring of the pilot valve.To get the analytic function formula about the two variables,i.e.the regulated pressure p_1 and the length reduction X_(t2) in advance is the most important step in design.The results show that the angle feedback pressure self-regulating system for hydraulic crane can effectively solve the problem of angle feedback pressur self-regulating of hydraulic cranes.
引文
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[13]文正民.液压阀孔的加工技术[J].液压气动与密封,2001,38(6):38 39.WEN Zheng-min.Technique of hole machining in hy-draulic valve[J].Hydraulics,Pneumatics&Seals,2001,38(6):38 39.
[14]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.SONG Hong-yao,DING Zhong-yao.Design and Cal-culation of Hydraulic Valve[M].Beijing:MechanicalIndustry Press,1979.
[15]张明松.改变溢流阀调压范围的简明计算方法[J].机械制造,2001,39(1):50 52.ZHANG Ming-song.A simple calculating method tochange pressure regulating range of overflow valve[J].Machinery,2001,39(1):50 52.
[2]刘洋.160t伸缩臂式铁路起重机液压系统的设计[J].液压与气动,2001,39(7):3 6.LIU Yang.160t telescopic railway crane hydraulic sys-tem design[J].Chinese Hydraulics&Pneumatics,2001,39(7):3 6.
[3]赵春红.起重机液压平衡回路的改进[J].起重运输机械,2000,27(8):33 35.ZHAO Chun-hong.Improvement of hydraulic balan-cing circuit for crane[J].Hoisting and Conveying Ma-chinery,2000,27(8):33 35.
[4]胡燕平,毛征宇,胡小平.用调压偏差为零的溢流阀提高泵缸液压系统技术性能[J].液压与气动,2001,39(4):15 17.HU Yan-ping,MAO Zheng-yu,HU Xiao-ping.Im-proving the performance of the pump-cylinder hydraulicsystem by using zero override relief valve[J].ChineseHydraulics&Pneumatics,2001,39(4):15 17.
[5]周琨敏,严向洁.液压传动系统特性研究[J].液压与气动,2001,39(7):7 9.ZHOU Kun-min,YAN Xiang-jie.Research on charac-teristics of hydraulic system[J].Chinese Hydraulics&Pneumatics,2001,39(7):7 9.
[6]王扬华.自制自控溢流阀[J].液压与气动,2000,38(5):44 46.WANG Yang-hua.The pressure relief valve made byoneself[J].Chinese Hydraulics&Pneumatics,2000,38(5):44 46.
[7]赵树山,马白,陈虹才.双出口溢流阀特性的实验研究[J].哈尔滨科学技术大学学报,1988,30(4):1 7.ZHAO Shu-shan,MA Bai,CHEN Hong-cai.A studyand test of double-outlet relief valve characteristics[J].Journal of Harbin University of Science and Technolo-gy,1988,30(4):1 7.
[8]方桂花,汪建新,张玉宝.液压传动[M].北京:地震出版社,2002.FANG Gui-hua,WANG Jian-xin,ZHANG Yu-bao.Hydraulic Transmission[M].Beijing:EarthquakePress,2002.
[9]Dransfield P.Hydraulic Control Systems———Designand Analysis of Their Dynamics[M].Beijing:SciencePress,1987.
[10]杨国平,舒林秋.液压起重机变幅油路的计算机动态仿真[J].建筑机械,1998,16(3):23 25.YANG Guo-ping,SHU Lin-qiu.Computer dynamicsimulation of radius-changing hydraulic circuit for hy-draulic crane[J].Construction Machinery,1998,16(3):23 25.
[11]郑红梅.仿真直动式溢流阀瞬态响应的键合图法[J].阀门,2001,25(5):12 16.ZHENG Hong-mei.Bond graph method for the emu-lation of direct-acting spillover valve’s transient re-sponse[J].Valve,2001,25(5):12 16.
[12]胡燕平,毛征宇.溢流阀稳态调压偏差对液压提升机控制性能的影响[J].矿山机械,2001,26(6):4849.HU Yan-ping,MAO Zheng-yu.Effects of overflowvalve stability pressure governing deviation on controlperformance of hydraulic hoist[J].Mining&Pro-cessing Equipment,2001,26(6):48 49.
[13]文正民.液压阀孔的加工技术[J].液压气动与密封,2001,38(6):38 39.WEN Zheng-min.Technique of hole machining in hy-draulic valve[J].Hydraulics,Pneumatics&Seals,2001,38(6):38 39.
[14]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.SONG Hong-yao,DING Zhong-yao.Design and Cal-culation of Hydraulic Valve[M].Beijing:MechanicalIndustry Press,1979.
[15]张明松.改变溢流阀调压范围的简明计算方法[J].机械制造,2001,39(1):50 52.ZHANG Ming-song.A simple calculating method tochange pressure regulating range of overflow valve[J].Machinery,2001,39(1):50 52.
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