Stiffness Characteristics of a Basic Nonlinear Air Spring Model

This study predicts the characteristics of a compressible polytropic air spring model. A second-order nonlinear autonomous air spring model is presented. The proposed model is based on the assumption that polytropic processes occur. Isothermal and isentropic compression and expansion of the air within the spring chambers are the two scenarios that are taken into consideration. In these situations, the air inside the spring chambers compresses and expands, resulting in nonlinear spring restoring forces. The MATLAB/Simulink software environment is used to build a numerical simulation model for the dynamic behavior of the air spring. To quantify the values of the stiffnesses of the proposed models, a numerical solution is run over time for various values of the design parameters. The isentropic process case has a higher dynamic air spring stiffness than the isothermal process case, according to the results. The size of the air spring chamber and the area of the air spring piston influence the air spring stiffness in both situations. It is demonstrated that the stiffness of the air spring increases linearly with increasing piston area and decreases nonlinearly with increasing air chamber length. As long as the ratio of the vibration’s amplitude to the air spring’s chamber length is small, there is good agreement in both scenarios between the linearized model and the full nonlinear model. This implies that linear modeling is a reasonable approximation of the complete nonlinear model in this particular scenario.

Simulation Research on an Active Anti-Roll System for an Air Spring Passenger Car

To reduce the roll movement of an air spring passenger car, an active anti-roll system is developed, which is constructed with hydraulic and pneumatic units to change spring rate during cornering. For the comparing research between the passive and active system, a two-track vehicle model and a co-simulation model of air spring system are built. For the simulation research on the linear movement of the actuator, a mathematical model is considered as dynamical subsystem in the co-simulation model. To active control the roll angle of vehicle body, a sliding-mode controller with optimized control parameters for the test vehicle is introduced into the model. The characteristics of sliding-mode controller is discussed and the validation of active antiroll control is proved by comparison with other control methods. The results show that the roll angle of air spring vehicle is reduced obviously with the active anti-roll actuator in comparison with that of the passive system. Compared with other control methods, sliding-mode controller has an advantage of shortest switching times, which leads to a longer lifetime of actuator and valves.

Dynamic frequency response characteristics of a compound regulative quasi-zero stiffness air spring system

Quasi-zero stiffness(QZS) device is widely studied for their better performance in low-frequency and micro-vibration isolation due to the high-static and low-dynamic(HSLD) stiffness characteristics.The previous QZS isolator with determined parameters is not suitable for variable isolated mass.In this study,a novel compound regulative quasi-zero stiffness air spring(CRQSAS)has been proposed and designed by introducing a bidirectional regulator for the horizontal air springs.The CRQSAS could change the quasi-zero region depending on the payload.To identify the parameters of the convoluted air spring(CAS) and novel rubber air spring(NRAS),the air spring testing system is established.The stiffness functions of air springs are obtained by the multi-parameter fitting method.According to the structure of the CRQSAS,the dynamic model of the system is analyzed and simplified by Taylor Expansion.The harmonic balance method(HBM) is applied to calculate the frequency response and absolute displacement transmissibility.An experimental prototype has been set up to verify the theoretical model and simulation.Compared with the single NRAS,CRQSAS performs better in low-frequency and micro-amplitude vibration.The research proves that CRQSAS is a passive device widely applied for improving isolation precision under low-frequency vibration.

The error research on vertical rigidity theory’s formula of airborne air spring

On the basis of analyzing the result of numerical simulation and that of theoretical analysis,the systematic error of some air spring's theoretical formula is researched. The result shows that the vertical stiffness's theoretical formula of air spring owes the systematic error. And the systematic error is relative to the three supposed conditions which are used in the process of theoretical deduction. However,the systematic error is small enough so that the supposed conditions of theoretical formula are reasonable. Moreover,with the increase of initial inner pressure,the systematical error increases.

空气弹簧自由边界模拟控制策略研究

针对空气弹簧水平多点支撑自由边界模拟系统存在的过约束、难收敛和非线性控制问题,首先,采用自由度解耦控制方式,在削弱系统内力的基础上,将空间自由度的控制目标分解为每一个控制通道的控制目标,解决了系统过约束问题;其次,利用改进积分分离(proportion integration differentiation,简称PID)控制算法克服系统超调,解决了系统震荡收敛问题;最后,采用经验数据对空气弹簧刚度进行实时二维插值补偿,解决了系统非线性问题。实测结果表明,该控制系统设计合理,系统运行过程平稳,通道间同步性较好,控制策略满足模态试验边界的模拟要求。

Design and experiment of high-speed straw cleaning unit with double air springs

No-tillage planters need to be equipped with row cleaners to remove post-harvest plant residue from the seedbed.The two-disc row cleaners cannot effectively remove the plant residue at high speed because the working depth is unstable,which leads to poor seeding quality of the seeder.A straw cleaning unit with double air springs was designed to achieve better straw cleaning performance at high speeds.The analysis of the mechanical characteristics of the double air spring system showed that it enabled separate adjustment of force and stiffness.A dynamic model of the straw cleaning unit was established,and the effectiveness of the double air spring system with adjustable stiffness in stabilizing the working depth of the row cleaners was analyzed.Field experiments were conducted to evaluate the straw cleaning performance and consistency of downforce against the ground of the straw cleaning unit with double air springs at different high speeds.The results showed that the stiffness of the double air spring system for better straw cleaning performance of the straw cleaning unit was different at different working speed,and the required stiffness increased as the working speed increased;When the working speed was 8-12 km/h,the coefficient of variation of cleaned strip width was 6.9%-12.1%,the straw cleaning rate was 81.6%-92.2%and the root mean square error of downforce was 19.93-28.63 N;the coefficient of variation of cleaned strip width was moderately positively correlated with the root mean square error of downforce,and the cleaned strip width consistency was better when the root mean square error of downforce was lower than 25.00 N.

Analyses of spring mean circulations for major andminor dust storm years in China-Mongolia area

To better understand the dust storm (hereafter DS) inducing circulation in the China-Mongolia (CM) DS activity area,the spring mean circulation features and differences on lower levels in three subregions of the CM DS area for the majorandminor-DS years have,as a whole (not partly),been analyzed,utilizing the National Centers for Environmental Prediction and the National Center for Atmospheric Research (NCEP/NCAR) reanalyzed gridded data,the observed DS frequency data in the CM area,and the composite analysis method.The main conclusions are as follows:(1) Judging from the differences in the DS-inducing systems,dust origins,paths of invading cold air,and main DS-strike areas,the whole CM DS area is roughly divided into the three subre-gions:the East-,Middleand West-CM subregions (in this paper,referred to as E-,M-,and W-CM).(2) In major DSs during spring over the E-CM,the middleand lower-level troughs or cyclones over the Japan Sea and northeastern China (NEC) domi-nate.The invading cold air along the northeastern (NE) or north by east (NE) path often causes the DS in the E-CM region.But nearly the opposite is true inminor DS during spring in E-CM.(3) In the major DS during spring over the M-CM region,the Mongolian troughs or cyclones are the main DS-inducing systems.The strong invading cold air along the northwestern (NW)or north by west (Nw) path causes the DSs in the M-CM region.(4) In the major DSs during spring over the W-CM region,the South Xinjiang heat lows prevail,the intruding cold air has a western path,and creates the DSs in South Xinjiang.(5) In the past 50 years,the DSs over the M-CM region have had the most severe impact on the preceding three subregions of the CM DS area.Overall,DS activities over all of three regions of the CM area decreased in the past (particularly,over Mand W-CM regions since the mid-1980s.But there existed a short and sudden increasing in E-CM in the years 2000-2002.(6) It is circulation changes and desertification evolutions that cause the yearly and decadal changes of DS in CM area,especially the former.With the backdrop of global warming in the future,perhaps the decreased DS activities over Mand W-CM will persist for some time again,and special attention should be paid to ones over E-CM or to the individual DS events over Mand W-CM.

低频非线性浮筏隔振装置设计及特性研究

低频振动噪声影响水下装备声隐身性能。在原气囊隔振装置基础上,通过结构改进设计,使得侧向气囊能够为系统提供负刚度,通过与垂向气囊并联,设计了一种新型非线性浮筏隔振装置,提升了隔振装置的低频隔振能力。新型隔振装置由“侧向气囊-万向节-垂向气囊”非线性隔振器组和浮筏组成。分析了侧向气囊为系统提供负刚度原理,建立了非线性浮筏隔振装置六自由度动力学模型,设计了新型隔振装置样机并开展了相关性能试验。理论分析和试验结果表明,新型非线性浮筏隔振系统垂向一阶固有频率约为原系统的50%,垂向隔振性能提升了约6 dB,侧向隔振性能与原系统相当。此外,也研究了非线性浮筏隔振系统的摇摆稳定性。研究结果表明,在重载情况下,新系统能够具备较好的摇摆稳定性。

某型振动台台面支撑控制系统的设计与实现

某型振动台采用永磁式电动振动台激振方式,为了实现该振动台台面的自动调平、定位和隔振,采用空气弹簧柔性支撑和电动推杆刚性支撑对振动台进行台面支撑。为了实现台面支撑的电气控制,设计了一套控制系统。控制系统基于西门子S7-200 SMART系列PLC和MCGS触摸屏设计,采用重量计算粗调辅助补偿和PID闭环精调的控制策略,给定合适的PID参数,有效解决了气路控制中存在的滞后问题和多个空气弹簧自动调平的耦合问题。调试结果表明,台面支撑控制系统实现了100 s内完成自动调平及定位,台面支撑各点的位移误差控制在了0.5 mm以内。

空气弹簧组件对列车磁悬浮系统的影响

[目的]为研究作为组件之一的空气弹簧对列车磁悬浮系统的影响,解决磁浮列车磁悬浮系统因空气弹簧的影响而导致的悬浮性能变差的问题,开展了空气弹簧对磁悬浮系统性能影响的机理研究和仿真分析。[方法]首先建立不含空气弹簧的磁悬浮模型,并在此基础上设计控制算法,根据磁悬浮系统的性能指标,设计其最优控制参数;在控制算法和最优控制参数确定之后,再将空气弹簧的影响考虑到磁悬浮系统模型中,以研究空气弹簧的刚度对磁悬浮性能的影响。采用MATLAB软件对磁悬浮系统的性能进行了仿真,仿真过程中,在不改变控制参数时改变空气弹簧的刚度,以观测磁悬浮性能的变化情况;当磁悬浮性能变差时,通过优化控制参数,使得磁悬浮性能保持最优。[结果及结论]仿真结果表明:当空气弹簧的刚度在某一范围内时,刚度越大越不利于磁悬浮系统的稳定;在空气弹簧的刚度增大时,适当增加控制系统的刚度和阻尼会有利于磁悬浮系统的稳定。

微振动环境下空调系统减振降噪技术应用研究

为降低某地下厂房空调系统运行时产生的振动与噪声对精密仪器测试平台的影响,提出了一种空调系统减振降噪综合治理方法,应用低频气囊隔振装置及肘形挠性接管、弹性马脚等隔振元件,使空调机组隔振量达到45dB,应用阵列式消声器、双层微穿孔吸声板等降噪元件,使测试厂房空气噪声降低22dB(A)。综合治理后,测试平台基座线性加速度降低13.55dB,满足了该厂房测试平台微振动环境要求。

船舶主机气囊隔振系统动态特性分析

提出了将气囊隔振器应用于船舶主机隔振,介绍了该隔振装置的特性,并进行了动力学分析。分析表明,气囊隔振系统能够大幅度减小主机激振力向船体基座的传递。在其他条件不变时,系统具有定常频率特性,各气囊压力的分布对系统固有频率、力传递特性没有影响,而对主机输出端的位移有一定影响,应该通过优化设计使联轴节的振动最小。

汽车空气悬架系统的发展概况

叙述了空气悬架系统的工作原理及特点,介绍了国内外空气悬架系统的发展概况,并对其前景作了预测,为空气悬架系统的设计提供了借鉴。

轨道车辆用空气弹簧的刚度特性试验

空气弹簧是轨道车辆控制振动的关键部件之一,具有减振效果好,重量轻和刚度可调等优点,已被广泛应用于铁路客车、地铁、轻轨和动车组上。刚度是表征空气弹簧性能的重要参数,它直接反映空气弹簧在静态条件下承受作用力的能力,所以,刚度试验结果的准确性至关重要。因此,如何通过试验来验证空气弹簧产品特性,保证产品质量,势在必行。

可调刚度膜式空气弹簧特性试验研究

以某种膜式空气弹簧为研究对象,在分析空气弹簧特点及工作原理基础上,建立空气弹簧特性试验系统,完成空气弹簧刚度特性实验和电磁阀充放气实验。通过一定弹簧高度下气囊内部气体的充放气实验,了解电磁阀开关时间与弹簧内部气体压力的关系;通过对空气弹簧进行斜坡信号加载实验,了解一定初始压力下空气弹簧有效面积变化、有效容积变化和弹簧刚度变化。试验结果将为基于电控空气悬架的汽车平顺性控制研究奠定基础。

精密空气弹簧隔振平台固有频率的研究

固有频率是空气弹簧隔振平台的重要物理参数之一,也是估计和衡量隔振系统隔振传递率大小的重要参数,但其理论计算与实际测试值的一致程度不易明确。以中国计量学院重中之重实验室的空气弹簧隔振平台为例,改进了隔振平台的动力学模型,得到了该隔振平台固有频率的理论值为1.28 Hz。然后,对实验得到的时域响应曲线进行FFT变换,得到隔振平台固有频率的实测值为1.22Hz,二者相对误差小于5%,达到了预期的研究目标。对误差的来源也进行了简要的分析。

空气弹簧对车辆曲线通过性能的影响

建立了考虑左右空气弹簧垂向耦合模型的车辆系统数学模型,由理想气体的状态方程得到空气弹簧的力学方程,分析了车辆通过曲线时车辆与空气弹簧的动态特性。仿真结果表明:由于高度阀的动作,车辆在驶出曲线后各空气弹簧的压力不一致,导致车体不能回到静平衡位置;车辆以正常速度通过曲线时,车辆曲线通过动力学性能变化不大;在车辆多次通过同一种曲线的较恶劣工况时,空气弹簧内气压变化范围是一定的;增加抗侧滚刚度能明显抑制车体侧滚,从而减小空气弹簧内气压的变化量;增大空气弹簧横向跨距,并选择合适的刚度和阻尼,能使车辆驶出曲线后各空气弹簧压力接近静平衡值。

汽车耦合空气弹簧悬架系统动力学模型的研究

推导了空气弹簧、高度阀、连接管路子模块的力学方程,提出了模块化的耦合空气弹簧悬架模型,该模型考虑了高度阀的死区、饱和特性以及节流管路的流量特性等非线性的影响,仿真结果表明,耦合空气弹簧动力学模型能反映空气弹簧相互作用和高度阀充排气对车体抗侧倾的影响,因而可以更加真实反映空气悬架系统的动力学特性。

和谐号动车组悬挂设备及控制

和谐号动车组悬挂控制设备由高度阀、平均阀、安全阀、电磁阀、压力开关、溢流阀、节流阀和塞门组成,可以根据载荷的变化自动控制空气弹簧压力,保证每节车或单车保持设定高度一致,同时检测出两个转向架上的空气弹簧压力平均值,并发送给制动控制系统。空气悬挂控制设备还采取各种安全控制措施,确保了和谐号动车组的安全运行。

蓄能式液压发射装置设计与分析

为了控制传统往复泵式武器发射装置发射武器时产生的剧烈喷注噪声,基于空气弹簧理论,提出了蓄能式液压平衡发射装置的设计方案。设计方案采用高压气体作为能量存储媒介,易于工程实现。基于水压平衡式发射模块的数学模型,建立了蓄能式发射装置发射武器的内弹道模型,并开展了仿真计算。仿真表明改进发射装置可以顺利完成武器发射任务,发射时间、武器出管速度等参数指标都符合正常武器发射的要求。该发射装置成功实现了低噪声发射并消除了传统发射装置发射武器带来的舱室增压及附带噪声的产生,对蓄能式武器发射装置设计研究及复泵式发射装置升级改造有重要参考意义。