Research on control method for machining non-cylinder pin hole of piston

The control method for machining non-cylinder pin hole of piston was studied systematically. A new method was presented by embedding giant magnetostrictive material (GMM) into the tool bar proper position. The model is established to characterize the relation between control current of coil and deformation of tool rod. A series of tests on deformation of giant magnetostrictive tool bar were done and the results validated the feasibility of the principle. The methods of measuring magne- tostrictive coefficient of rare earth GMM were analyzed. The measuring device with the bias field and prestress was designed. A series of experiments were done to test magnetostrictive coefficient. Experimental results supplied accurate characteristic pa- rameter for designing application device of GMM. The constitution of the developed control system made up of displacement detection and temperature detection for thermal deformation compensation was also introduced. The developed machine tool for boring the non-cylinder pin hole of piston has the micron order accuracy. This control method can be applied to other areas for machining precision or complex parts.

An Electro-Mechanical Controller for Adjusting Piston Pump Stroke On-the-Go for Site-Specific Application of Crop Nutrients

Nutrient application systems are designed to apply a relatively uniform amount of a fertilizer to agricultural fields. However, considerable variation in soil texture and other characteristics often occurs within and across production fields, which could have a major impact on fertilizer management strategies. Therefore, uniform application of a fertilizer over the entire field can be both costly and environmentally unsound. Due to their rugged and fool-proof design, crankshaft type piston pumps are widely used in agriculture. The on-the-go outlet flow of these pumps can only be varied by changing the drive shaft speed for each pump stroke setting. But only a limited range of flow rates can be achieved by changing the drive shaft speed. There is a need for an electronic controller, which can adjust the pump stroke on-the-go, for real-time, variable-rate application of crop nutrients. The Clemson “Electro-me-chanical controller for adjusting pump stroke on-the-go” was designed to replace the current manual stroke adjustment system on positive displacement piston pumps. This affordable system can be retrofitted on most John Blue - piston pumps for real-time adjustment of the pump stroke and can be controlled using pre-described position sequences (map-based) or real-time sensor commands (such as optical, pressure, and flow sensors) combined with fertilizer calculation algorithms. In addition, it can adjust pump stroke manually, using an eclectic dial from the tractor’s cab.

Frequency compensation control method for opposedpiston two-stroke folded-cranktrain engine's common rail system by loop-shaping theory

A frequency compensation control method for the opposed-piston two-stroke folded-cranktrain（ OPFC） diesel engine＇s common rail system is presented as a result of the study of the loop-shaping theory. A common rail working process and the classical frequency control theory are combined to construct a frequency restriction of common rail pressure. A frequency compensator is utilized to improve the robustness of multiplicative perturbations and disturbance. The loop-shaping method has been applied to design the common rail pressure controller of the OPFC diesel engine. Simulation and bench test results show that in the condition of perturbation that comes from the effect of injection,multi-injection,fuel pumping of a pre-cylinder,and instantaneous pressure fluctuation,the controller indicates high precision. Compared with the original controller,this method improves the control precision by 67. 3%.

地铁活塞效应的节能综述研究

随着地铁行业的蓬勃发展,利用活塞风降低车站能耗成为目前研究的热点之一。首先整理与活塞效应相关的国内外文献,研究活塞效应的形成机理和特性,分析活塞效应对地铁环控系统产生的影响,发现两者间潜在的节能关系。其次分别对隧道活塞风与车站活塞风的利用策略进行综述研究,这些策略主要与通风井的相关设计、列车的行驶、站台门的选择以及门帘的安装等有关,合理地采用这些策略可以为车站降低能耗。最后提出了活塞风的利用原则,在活塞风满足乘客需求的情况下应当优先利用活塞通风,应根据风量、温湿度、二氧化碳浓度以及颗粒物浓度等参数评价活塞风是否满足需求。

气体活塞期间核查PACE6000高精度数字压力计方法

气体活塞作为实验室的最高标准,可以量值传递和核查实验室其他标准设备的稳定性、可靠性。PACE6000数字压力控制器是实验室频繁使用的设备,在周期内计量特性的稳定是量值传递的基础,使用过程中会受到很多外部因素的影响,频繁使用、使用年限较长、经常更换使用环境等因素都会对数字压力控制器的计量特性产生不可预测的影响。为确保数字压力控制器量值传递的准确性,提高检定和校准结果的可靠性,降低出错风险,需要在数字压力控制器两个相邻检定或校准周期内,开展期间核查工作。

轴向柱塞泵变量机构的建模与仿真研究

针对重载大排量轴向柱塞泵的变量机构设计问题,以A4VSG750-HD型轴向柱塞泵为例,采用AMESIM软件实现了其变量机构的建模,通过分析先导控制阀与变量机构的力传递特性,对其变量特性进行了仿真分析。与传统的基于结构的建模方法相比,该方法简化了变量机构的模型,仿真结果准确。

Output Characteristics of a Series Three-port Axial Piston Pump

Driving a hydraulic cylinder directly by a closed-loop hydraulic pump is currently a key research area in the field of electro-hydraulic control technology,and it is the most direct means to improve the energy efficiency of an electro-hydraulic control system.So far,this technology has been well applied to the pump-controlled symmetric hydraulic cylinder.However,for the differential cylinder that is widely used in hydraulic technology,satisfactory results have not yet been achieved,due to the asymmetric flow constraint.Therefore,based on the principle of the asymmetric valve controlled asymmetric cylinder in valve controlled cylinder technology,an innovative idea for an asymmetric pump controlled asymmetric cylinder is put forward to address this problem.The scheme proposes to transform the oil suction window of the existing axial piston pump into two series windows.When in use,one window is connected to the rod chamber of the hydraulic cylinder and the other is linked with a low-pressure oil tank.This allows the differential cylinders to be directly controlled by changing the displacement or rotation speed of the pumps.Compared with the loop principle of offsetting the area difference of the differential cylinder through hydraulic valve using existing technology,this method may simplify the circuits and increase the energy efficiency of the system.With the software SimulationX,a hydraulic pump simulation model is set up,which examines the movement characteristics of an individual piston and the compressibility of oil,as well as the flow distribution area as it changes with the rotation angle.The pump structure parameters,especially the size of the unloading groove of the valve plate,are determined through digital simulation.All of the components of the series arranged three distribution-window axial piston pump are designed,based on the simulation analysis of the flow pulse characteristics of the pump,and then the prototype pump is made.The basic characteristics,such as the pressure,flow and noise of the pumps under different rotation speeds,are measured on the test bench.The test results verify the correctness of the principle.The proposed research lays a theoretical foundation for the further development of a new pump-controlled cylinder system.

船用柴油-天然气双燃料发动机活塞熔顶分析与改进

在船用柴油-天然气双燃料发动机的开发过程中,铸铝活塞顶面出现了熔顶现象。经过燃烧分析,发现该问题的主要原因在于柴油喷射控制策略导致的爆震裕度不足,以及对试验边界条件的变化过于敏感,造成了缸内温度和活塞顶面温度的异常升高,最终引起活塞的熔顶。通过优化电控标定、改进活塞内冷油道设计以及进行活塞顶面陶瓷化处理,提升了爆震裕度,活塞顶面温度明显降低,问题得到了有效解决。

Nonlinear aeroelastic analysis of a two-dimensional wing with control surface in supersonic flow

Based on the piston theory of supersonic flow and the energy method, a two dimensional wing with a control surface in supersonic flow is theoretically modeled, in which the cubic stiffness in the torsional direction of the control surface is considered. An approximate method of the cha- otic response analysis of the nonlinear aeroelastic system is studied, the main idea of which is that under the condi- tion of stable limit cycle flutter of the aeroelastic system, the vibrations in the plunging and pitching of the wing can approximately be considered to be simple harmonic excita- tion to the control surface. The motion of the control surface can approximately be modeled by a nonlinear oscillation of one-degree-of-freedom. The range of the chaotic response of the aeroelastic system is approximately determined by means of the chaotic response of the nonlinear oscillator. The rich dynamic behaviors of the control surface are represented as bifurcation diagrams, phase-plane portraits and PS diagrams. The theoretical analysis is verified by the numerical results.

Recent Progress in Heavy Fuel Aviation Piston Engine

Heavy fuel aviation piston engines(HF-APEs)refer to the engine using fuels with high flash point,such as kerosene or light diesel.Here technique specifications of some classical foreign HF-APEs(Hirth3503,Zanzottera 498)are introduced.Recent progress and trend of fuel injection,fuel ignition,working cycle,intake charging,thermal management and electronic control of HF-APE are compared and summarized.Emphases are put on the technological difficulties,solutions and development tendency in the design,retrofitting and manufacturing of HF-APE aiming to provide references for the research of related area and the development of prototype HF-APE in China.

Pressure distribution of combining center cavity slipper for axial piston pump

In order to improve lubricating characteristics of slippers in an axial piston pump, the combining center cavity slipper approach was proposed based on slipper shape and moving characteristic. The cylindrical coordinate was used in the lubricant area and mesh was made. The blockweight approach was implemented to deal with non-coincidence of mesh and shallow recess border in numerical method. The finite control volume method was applied in calculating pressure distribution. The flow conservation equation and film thickness model were resolved through Gauss-Siedel relaxation iteration. The calculation and analysis results indicate that compared to the slipper （1） slip- per pressure distribution is improved; （2） hydrodynamic pressure of the combining slipper is greatly increased; （3） inclining degree is greatly reduced; （4） negative pressure in lubricant film disappear. So the combining center cavity slipper is lubricated better.

基于Inspire的S195柴油机活塞轻量化分析

采用Inspire软件对S195柴油机活塞进行轻量化设计,分析了设计流程,确定了载荷和约束条件,探讨了形状控制方法和几何重构方法对优化结果的影响。通过改变形状控制方法和几何重构方法设计了12种优化方案,并通过强度校核对比,最终确定对称的手动重构方案为最优结果。

活塞式排气阀机械结构优化与应用研究

海上电泵机采完井中常在电缆穿越式封隔器上配置排气阀,用于排出封隔器下方积聚的气体从而避免电泵气锁。常用的排气阀是通过液压控制本体内活塞进行轴向移动来实现排气通道的启闭,存在加工精度要求苛刻、加工成本高、启闭压力不稳定、防震防碰效果差及成品率低等问题。通过机械结构优化设计出一种新型排气阀,其启闭压力稳定性大大提高,同时下入深度由552 m增加到1000 m以内,具有加工组装简便、生产成本低、成品率高的优势。室内试验验证通过后,该活塞式排气阀被推广到渤海和南海电泵机采井生产中,并广泛替代了原有技术排气阀。

基于模糊PID的开式径向变量柱塞泵控油压机系统特性实验研究

传统的大型油压机的传动系统效率和控制精度较低。在节能降耗、低碳环保的理念下,高精度泵控技术与高性能油压机控制系统的融合问题,目前已经得到了业界的广泛关注。为了提高开式径向变量柱塞泵控油压机系统的位置控制精度,设计了自适应模糊PID控制策略,并对不同工况下的快锻系统特性进行了研究。首先,建立了数字控制增强型径向柱塞泵、开式泵控非对称缸的数学模型,推导了开式径向变量柱塞泵控油压机系统的数学模型,并设计了自适应模糊PID控制器;然后,通过AMESim-Simulink联合仿真,对不同工况下带载快锻系统的控制特性展开了仿真研究;最后,依托0.6 MN泵控油压机实验测试平台,验证了自适应模糊PID的有效性以及快锻系统的控制特性。研究结果表明:在快锻频率为1 Hz、行程为20 mm、负载为1.2×10^(5)N和快锻频率为0.5 Hz、行程为40 mm、负载为2.0×10^(5)N的2种工况下,开式径向变量柱塞泵控油压机引入自适应模糊PID控制系统后,其具有运行平稳、响应迅速的特点,且位置精度误差均小于0.5 mm。上述结果验证了开式径向变量柱塞泵控油压机联合仿真模型的正确性和控制器的有效性。

基于预测控制的活塞式压力计活塞位置平衡技术

高压(大于250 MPa)全自动活塞式压力计需要控制系统能快速找到达到活塞稳定浮起的位置平衡点。为了减少仪器体积,一般采用尽可能小的活塞直径,微小的压力变动就会导致活塞位置的起伏。为了快速实现活塞位置的快速平衡,提出了使用广义预测控制(GPC)活塞位置平衡的控制方法。在提出的预测控制算法中,综合考虑了活塞压力计在加压过程中存在的多个变量对活塞下降速度的影响,通过对输入输出的模型辨识,构造出压力计活塞位置控制的数学模型,并通过广义预测算法预测活塞的运动行为。结果表明,广义预测控制对于活塞位置的快速平衡具有良好效果。

车用柴油机缸套活塞磨损试验台设计

为研究南疆风沙环境中车用柴油机在不同沙尘浓度、工作速度、环境温度等条件下对发动机缸套活塞磨损的影响,设计柴油机缸套活塞磨损试验台。试验台主要由风沙输送装置、驱动传动装置、磨损测量及测试系统等组成,通过风沙输送装置模拟沙尘浓度、速度等参数变化的要求;设计的测控系统能够完成工作压力、环境温度、沙尘流量、转速等传感信息的收集和可视化。试验台采用动力机械常用的柴油发动机作为研究对象,适用于实验室中在研发缸套活塞耐磨材料时的测试装备。此试验机操纵方便,可拓展性强,可用于研究南疆风沙环境对内燃机磨损的规律、空滤的堵塞机制、进气阻力分析等。

活塞发动机的永磁起发电机无位置传感器控制技术

针对活塞发动机起动静力矩大、转动惯量小,高速工作时活塞发动机油门响应慢,转速波动大,匹配的外转子永磁起发电机低电感、高频率、无位置传感器,提出基于数学模型与锁相环相结合的无位置估算策略。起动时采用单级锁相环进行转速和位置估算,通过锁相环的高环路增益设计来保证位置估算的快速性。利用发动机惯量小的特点,通过施加随机力矩,使发动机获得较高加速度,产生较高反电势,最终使锁相环快速进入稳定工作状态。通过对角频率进行正向补偿和对正负相频率进行差异限幅,实现反转起动抑制。发电时采用快速稳速内环与慢速稳压外环相结合的控制策略。发电位置与转速估算采用两级锁相环实现,第一级锁相环通过高环路增益设计保证快速性,满足宽转速范围应用需求;第二级锁相环利用第一级锁相环输出的角频率,通过低环路增益设计,实现位置信号计算的精确性。实测结果表明,起动时,在任意发动机静止位置,控制器仅输出2 Nm对应的三相电流,就可实现最大5 Nm阻力矩的发动机正转起动;发电时,转速稳定精度可达±30 r/min,电流频率上限为1 kHz。所提出无位置传感器控制方法适合增程式无人机用活塞发动机。

无人机动力系统综合控制研究

动力系统是无人机安全、可靠飞行的动力保障。文中以某型航空涡轮增压活塞发动机为动力的无人机为例,在无人机飞行剖面内对动力系统进行综合控制。采取特征参数闭环控制、动力系统状态信息实时采集并进行目标趋势分析与故障诊断、执行机构集中管理与控制等手段,合理地调整动力系统工作状态,以延长发动机使用寿命,提高发动机可用功率,最大限度发挥发动机的装机特性,从而更好地满足无人机使用需求。统计结果表明,动力系统采用综合控制技术后,发动机使用高度提升36%,相同燃、滑油装载条件下,发动机运转时间延长25%,动力系统在线故障检测率高于92.5%、故障定位率高于96%。达到了动力控制与调节功能的可行性、匹配性、协调性与可靠性的目的。

基于时频控制的恒流量泵机理研究

针对转向系统恒流量需求的背景,以简化结构提高可靠性为目标,以对应于转速的运动频率、有效吸油行程及其行程占比的控制,提出基于时频控制的恒流量泵原理,并从理论角度验证了其基本机理。以某型恒流径向柱塞泵开发为背景,开展了相关的仿真研究,针对该型柱塞泵关键参数进行了敏感性分析,对恒流控制的影响因素进行了解析。相关研究成果可拓宽恒流泵的设计思路,具有较强的理论及工程价值。

基于往复阀减振的轴向柱塞泵压力特性分析

采用传统三角槽配流盘的轴向柱塞泵在过渡区不能完全消除由于换向产生的压力脉动,同时由于节流的影响,会产生明显的流量倒灌现象。在不对缸体或配流盘进行颠覆性设计的情况下,提出一种压力控制往复阀结构串联于各柱塞腔之间,从而缓冲过渡区的压力脉动,减小过渡区产生的振动,并取消配流盘的三角槽结构,从而减少流量倒灌。给定往复阀的直径等参数,通过仿真分析发现,该结构在过渡区产生的压力脉动仅为2.5%,相对于三角槽配流盘可以有效的降低轴向柱塞泵在高低压过渡区过程中的压力脉动。