【作者】 张晓刚；

【导师】 权龙；

【作者基本信息】 太原理工大学 ， 机械电子工程， 2011， 博士

【摘要】 轴向柱塞泵作为液压系统中关键性动力元件,具有压力高、调速范围广、配流结构易于改型等特点,能够适应液压系统简化回路、节能环保的发展要求。采用液压泵直接控制液压缸的运动,是提高电液技术能量效率最直接的方法,是该领域国际上的研究热点,国内外在这方面都开展了许多研究工作。目前,液压系统主要采用阀控方式,存在不足是产生大的节流损失,降低了系统能量效率。人们早就明确,改变这种状况的最有效方式是采用无阀的泵直接控制技术,即通过控制液压泵的排量或转速,改变提供到系统的流量,控制液压缸的位移、速度和输出力的大小。根据对象不同,泵控技术有泵控缸、泵控马达两类,泵控缸又包含泵控对称缸与泵控差动缸。经过20多年的努力,直接泵控技术已取得了非常大的进展,发展了高动态响应比例和伺服泵,引入了变转速控制技术,解决了液压缸两腔的预压紧问题,尤其是对双出杆的对称液压缸,控制技术已非常成熟,并已经在航空领域获得了应用。但是,对于液压技术中广泛应用的差动液压缸,虽然已经取得了许多进展,现有技术都不理想,为了补偿差动缸不对称流量,需要采用许多辅助的方法。比如采用液压泵和马达组成的液压变压器补偿差动缸的不对称流量；采用液控单向阀补油、平衡差动缸流量差的方法。但是,由于差动缸的特殊结构,现有的技术还是不能做到像泵控双出杆缸一样,无需外部的辅助元件,只用一台液压泵就能闭环控制差动缸的运动。为了实现这一目标,本文依据非对称阀控制非对称缸的思想,提出在轴向柱塞泵中采用非对称配流方法控制差动缸的原理,在理论分析的基础上,从建模分析、仿真运算、三维实体建模到研制出一种新型液压泵,并在不同的工作模式下与仿真结果进行试验对比,得出比较合理的新型泵关键元件的结构参数,使样机泵的压力脉动效果达到与现有泵相当的水平,最终达到单泵可以补偿差动缸的不对称面积,闭环控制差动缸的运动,优化回路结构。具体的步骤是,对现有轴向柱塞泵进行重新设计和改型,将轴向柱塞泵的排油窗口保持不变,吸油窗口改型设计为两个窗口,一个窗口接液压缸的有杆腔,另一个窗口连通低压油箱,成为三配流窗口轴向柱塞泵,通过改变泵的排量或转速,直接控制差动缸的运动,相对于现有技术采用液压阀补偿差动缸面积差的回路,达到简化油路、提高系统的能量效率。三配流窗口轴向柱塞泵还能够同时输出两路不同压力的流量,控制两个液压执行器的运动。设计和改型过程中,首先,采用机电系统通用仿真软件SimulationX建立考虑单个柱塞运动特征、油液压缩性和配流面积随转角变化的液压泵仿真模型,通过数字仿真确定泵主要结构的关键参数,特别是缸体和配流盘减震槽的尺寸,采用数字仿真对泵的流量特性、压力特性进行分析；其次,制造出样机泵后,在试验台上对多种转速下泵的压力、流量、容积效率和噪声等特性进行测试,验证原理和仿真设计的正确性,重新设计和改型的泵配流窗口结构,有串联和并联两种形式；第三,利用Matlab/Simulink软件建立泵变转速控制差动缸闭式系统仿真模型,对差动缸运动过程中所受到的不同工况进行仿真研究,根据闭式回路动作要求,在试验台上对泵的输出流量、压力以及差动缸的位移、输出力、速度等参数进行测试,最终通过试验结果验证仿真结果。研究成果表明,采用新型配流原理研制成功的三配流窗口轴向柱塞泵,完全可以平衡差动缸两腔的不对称流量,将在不久的具体设备应用中发挥更大的作用。更多还原

【Abstract】 As the crucial power components in hydraulic system, axial piston pump has the characters of high pressure, wide speed adjustable range and easy-changed assignment structure and can meet the requirement of hydraulic system for simplifying loop, saving energy and protecting environment. The adoption of hydraulic pump to control directly the movement of hydraulic cylinder is the most direct way to improve the efficiency and energy of electro-hydraulic technology, which is also the international research hotspot in this field and a large amount of research upon this field has made. The present hydraulic system is value-controlling mostly which has disadvantage that leads to great throttling loss and decrease the using efficiency of system energy. It is clearly known that the most effective way to change this situation is to adopt the direct-controlling technology of pump without value-controlling. That is, by controlling the flow or rotate speed of hydraulic pump to change the flow to system and controlling the displacement, speed and output force of cylinder. According to the differential object, pump-control technology include pump-control motor and pump-control cylinder, pump control cylinder again include pump-control symmetric cylinder and pump-control differential cylinder. Passing more than20years’efforts the direct pump-control technology has made a lot of progress, developing the high dynamic response ratio and servo pump, introducing variable speed control technology, solving the tight prepressing problem of two cavity in hydraulic cylinder, especially for the symmetric cylinder, the control technology has perfected very well and applying it into aviation. But to the differential hydraulic cylinder which is widely used in hydraulic technology can still not meet the present need, though a lot of progress has been made. And to make up for the asymmetric flow of differential cylinder, many auxiliary methods has to be adopted such as using hydraulic transformer which is consist of hydraulic cylinder and motor to compensate the asymmetrical flow; adopting hydraulic controlled check valve compensate oil to balance differential cylinder flow difference. However, owing to the special structure of differential cylinder, the present technology can still not be made as pump-control symmetric cylinder which can use only one hydraulic pump controlling the movement of differential cylinder in the closed loop and without auxiliary components. To obtain the goal, the article will come up with the theory that applies asymmetric assignment method in axial piston pump to control differential cylinder according to the idea that asymmetric valve controlling asymmetric cylinder and on the basis of theory analysis, through the procedure of modeling construction, simulation, three-dimensional entity modeling to developing a new type hydraulic pump. The article will also include experimental contrast under different operating mode to work out a reasonable structural parameters of the new type pump key elements to accomplish the goal that the pressure pulsation effect of new type pump has the same level with the present pump, eventually realizing the single pump can compensate the asymmetric area of differential cylinder, control the movement of differential cylinder in closed loop and optimize circuit structure. The detailed procedures are in the following:redesign and remodel the present axial piston pump, keep the discharged window of the axial piston pump and redesigning the suction window into two windows in which one window links to rod cavity of the cylinder and the other one connects to low pressure oil tank to structure the three assignment windows axial piston pump, by changing the displacement or rotate speed of the pump to control the movement of the differential cylinder directly. To obtain goals of simplifying the oil-way and improving the energy efficiency of system which is better than the present technology that uses hydraulic valve to compensate the circuit of differential cylinder area difference. Meantime three assignment windows axial piston pump still can output two flows belonging to different pressure to control the movement of two hydraulic actuators. In the process of redesigning and remodeling, first, general simulation software of mechanical and electrical system SimulationX must be used to construct the hydraulic pump simulation model under the consideration of the movement character of single piston, compressibility oil and assignment area change with rotary angle. Then, digital simulation must be used to determine the key parameters of the primary elements in the pump, especially the size of cylinder and suspension groove of port plate, digital simulation is also used to analyze the flow features and pressure features of the pump; second, after the model pump is made out, the pressure flow, volumetric efficiency and noise of the pump under various rotate speed, must be tested on the experimental platform, in the end the validity of the principle and simulation design can be verified. The assignment windows structure of the redesigning and remodeling pump has two ways with series connection and parallel connection; third, the Matlab/Simulink software will be used to construct simulation model of closed system which pump control differential cylinder at variable speed. By simulated study on different operating mode during the movement of differential cylinder, according to operation requirement of closed loop, the output flow, pressure of the pump and the displacement, output force and speed of the differential cylinder are tested on the experimental platform, eventually the result of simulation is proofed by the result of test. The result of research shows that three assignment windows axial piston pump which is made according to the new assignment theory can completely balance the asymmetrical flow of the two cavity in differential cylinder and will play a more important role in the future application of concrete equipment.更多还原